U.S. patent application number 10/095622 was filed with the patent office on 2002-11-28 for magnetic element in a non-saturated region in a trnsformer/ inductor.
Invention is credited to Riggio, Christopher Allen, Woodland, Garth Blair.
Application Number | 20020176263 10/095622 |
Document ID | / |
Family ID | 23626491 |
Filed Date | 2002-11-28 |
United States Patent
Application |
20020176263 |
Kind Code |
A1 |
Riggio, Christopher Allen ;
et al. |
November 28, 2002 |
Magnetic element in a non-saturated region in a trnsformer/
inductor
Abstract
Single, multistage, and distributed magnetic switched and tank
resonant power conversion systems can use a transformer with a
magnetic element operating in a non-saturated region (NSME). The
NSME provides superior protection to conducted lightning
transients, superior thermal operating bandwidth, higher
magnetizing efficiency, greater flux/power density potential and
form factor flexibility when implemented with many circuit
strategies, some of which are disclosed herein. Efficient energy
storage and transfer is achieved by the optimized application of
NSME. The use of efficient rectifying flyback management techniques
protects switches and provides additional output. The preferred
embodiment teaches against common theories of transformers and uses
a NSME in the core.
Inventors: |
Riggio, Christopher Allen;
(Longmont, CO) ; Woodland, Garth Blair;
(Littleton, CO) |
Correspondence
Address: |
Patent Offices of Rick Martin
416 Coffman Street
Longmont
CO
80501
US
|
Family ID: |
23626491 |
Appl. No.: |
10/095622 |
Filed: |
March 11, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10095622 |
Mar 11, 2002 |
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09923027 |
Aug 6, 2001 |
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09923027 |
Aug 6, 2001 |
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09410849 |
Oct 1, 1999 |
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6272025 |
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Current U.S.
Class: |
363/24 |
Current CPC
Class: |
H02M 1/4258 20130101;
H01F 3/10 20130101; H02M 1/32 20130101; H02M 3/285 20130101; H01F
27/34 20130101; Y02B 70/1433 20130101; Y02B 70/10 20130101; Y02B
70/126 20130101; H01F 3/14 20130101; H02M 1/14 20130101; H02M
3/33569 20130101; H01F 1/14791 20130101 |
Class at
Publication: |
363/24 |
International
Class: |
H02M 003/335 |
Claims
We claim:
1. A transformer for use in a converter of a power supply, said
transformer comprising: a core; a primary winding wrapped around
the core; at least one secondary winding wrapped around the core;
and wherein the core comprises at least one magnetic element
operating in a non-saturated region (NSME).
2. A transformer comprising: a core; a primary winding wrapped
around the core; at least one secondary winding wrapped around the
core; and wherein the core comprises at least one magnetic element
operating in a non-saturated region (NSME).
3. The transformer of claim 2, wherein said NSME further comprises
a low permeability.
4. The transformer of claim 3, wherein the NSME further comprises a
mixture of 85% by weight of iron, 6% by weight of aluminum, and 9%
by weight of silicon, thereby providing a wide thermal operating
range for the magnetic element.
5. The transformer of claim 3, wherein the low permeability has a
range of one to 500 u.
6. The transformer of claim 5, wherein the NSME is an air magnetic
element.
7. The transformer of claim 2, wherein the NSME further comprises a
B-H curve characteristic ranging from B=1 to 10,000 gauss and H=1
to 100 oersteds.
8. A transformer comprising: a primary winding surrounding a
plurality of core elements; a secondary winding wrapped around a
member of the plurality of core elements; and wherein at least one
core element comprises a magnetic element operating in a
non-saturated region (NSME).
9. The transformer of claim 8, wherein said NSME further comprises
a low permeability.
10. The transformer of claim 9, wherein the NSME further comprises
a mixture of 85% by weight of iron, 6% by weight of aluminum, and
9% by weight of silicon, thereby providing a wide thermal operating
range for the magnetic element.
11. The transformer of claim 9, wherein the low permeability has a
range of one to 500 u.
12. The transformer of claim 11 wherein the NSME is an air magnetic
element.
13. The transformer of claim 8, wherein the NSME further comprises
a B-H curve characteristic ranging from B=1 to 10,000 gauss and H=1
to 100 oersteds.
14. A resonant sub-circuit comprising: a capacitor having a
connection to a magnetic element thereby forming a resonate
relationship there between; and wherein said magnetic element
further comprises a magnetic element operating in a non saturating
region (NSME) thereof.
15. The sub-circuit of claim 14, further connected to a filter
circuit, thereby giving the filter circuit a lower mass, complexity
and cost for a given filtering characteristic.
16. The converter of claim 15, wherein said NSME further comprises
a low permeability.
17. The converter of claim 16, wherein the NSME further comprises a
mixture of 85% by weight of iron, 6% by weight of aluminum, and 9%
by weight of silicon, thereby providing a wide thermal operating
range for the magnetic element.
18. The converter of claim 16, wherein the low permeability has a
range of one to 500 u.
19. The converter of claim 16, wherein the NSME is an air magnetic
element.
20. The converter of claim 16, wherein the NSME further comprises a
B-H curve characteristic ranging from B=1 to 10,000 gauss and H=1
to 100 oersteds.
21. The sub-circuit of claim 14, wherein the connection is a
parallel connection.
22. The sub-circuit of claim 14, wherein the connection is a series
connection.
23. In a power conversion circuit having an energized magnetic
element, the improvement comprising: said magnetic element
operating in a non saturating region (NSME) thereof; said magnetic
element having a natural frequency; and said energizing power
approximately matched to said natural frequency thereby providing a
higher power density, an improved thermal stability, and an
increased conversion efficiency.
24. The converter of claim 23, wherein said NSME further comprises
a low permeability.
25. The converter of claim 24, wherein the NSME further comprises a
mixture of 85% by weight of iron, 6% by weight of aluminum, and 9%
by weight of silicon, thereby providing a wide thermal operating
range for the magnetic element.
26. The converter of claim 24, wherein the low permeability has a
range of one to 500 u.
27. The converter of claim 24, wherein the NSME is an air magnetic
element.
28. The converter of claim 24, wherein the NSME further comprises a
B-H curve characteristic ranging from B=1 to 10,000 gauss and H=1
to 100 oersteds.
29. An inductor comprising: a core; a winding; and wherein the core
has a magnetic element operating in a non-saturated region
(NSME).
30. An inductor comprising: a plurality of cores; a winding around
at least one member N of the plurality of cores; and wherein the
member N has a magnetic element operating in a non-saturated region
(NSME).
Description
CROSS REFERENCE APPLICATIONS
[0001] This application is a divisional application of application
Ser. No. 09/923,027 filed 08/06/2001 which is a divisional of
application Ser. No. 09/410,849 filed 10/01/1999 and issued as U.S.
Pat. No 6,272,025 on 08/07/2001.
FIELD OF INVENTION
[0002] The present invention relates to converters, power supplies,
more particularly, to single, or multi stage, AC/DC or DC/DC
isolated and non-isolated push-pull converters including but not
limited to, forward, flyback, buck, boost, push pull, and resonant
mode converters, and power supplies, having individual or
distributed NSME with high speed FET switching and efficient
flyback management and or having input PFC (power factor
correction) and input protection from lightning transients. The
invention also allows the magnetic element(s) be distributed to
accommodate packaging restrictions, multiple secondary windings, or
operation at very high winding voltages.
BACKGROUND OF THE INVENTION
[0003] There are several basic topologies commonly used to
implement switching converters.
[0004] A DC-DC converter is a device that converts a DC voltage at
one level to a DC voltage at another level. The converter typically
includes a magnetic element having primary and secondary windings
wound around it to form a transformer. By opening and closing the
primary circuit at appropriate intervals control over the energy
transfer between the windings occurs. The magnetic element provides
an alternating voltage and current whose amplitude can be adjusted
by changing the number and ratio of turns in each set of the
windings. The magnetic element provides galvanic isolation between
the input and the output of the converter.
[0005] One of the topologies is the push-pull converter. The output
signal is the output of an IC network that switches the transistors
alternately "on" and "off". High frequency square waves on the
transistor output drive the magnetic element into AC (alternating
current) bias. The isolated secondary outputs a wave that is
rectified to produce DC (direct current). The push-pull converters
generally have more components as compared to other topologies. The
push-pull approach makes efficient use of the magnetic element by
producing AC bias, but suffers from high parts count, thermal
derating, oversized magnetics, and elaborate core reset schemes.
The destructive fly-back voltages occurring across the switches are
controlled through the use of dissipative snubber networks
positioned across the primary switches. Another of the topologies
is the forward converter. When the primary of the forward converter
is energized, energy is immediately transferred to the secondary
winding. In addition to the aforementioned issues the forward
converter suffers from inefficient (dc bias) use of the magnetic
element. The prior art power supplies use high permeability gapped
ferrite magnetic elements. These are well known in the art and are
widely used. The magnetics of the prior art power supplies are
generally designed for twice the required power rating and require
complex methods to reset and cool the magnetic elements resulting
in increased costs and limited operating temperatures. This is
because high permeability magnetic elements saturate during
operation producing heat in the core, which increases permeability
and lowers the saturation threshold. This produces runaway heating,
current spikes and/or large leakage currents in the air gap,
reduced efficiency, and ultimately less power at higher
temperatures and/or high load. The overall effects are, lower
efficiency, lower power density, and forced air/heatsink dependant
supplies that require over-rated ferrite magnetic elements for a
given output over time, temperature, and loading.
Improvements
[0006] The combined improvements of the invention translate to
higher system efficiencies, higher power densities, lower operating
temperatures, and, improved thermal tolerance thereby reducing or
eliminating the need for forced air cooling per unit output. The
non-saturating magnetic properties are relatively insensitive to
temperature (see FIG. 17), thus allowing the converter to operate
over a greater temperature range. In practice, the operating
temperature for the NSME is limited to 200 C. by wire/core
insulation; the non-saturating magnetic material remains operable
to near its Curie temperature of 500 C. What are needed are
converters having circuit strategies that make advantageous use of
individual and distributed NSME.
[0007] What are needed are converters having buffer circuits that
provide fast, low impedance critically damped switching of the main
FET's.
[0008] What are needed are converters that incorporate efficient
multiple "stress-less" flyback management techniques to rectify and
critically damp excessive node voltages across converter
switches.
[0009] What are needed are converters having flux feedback
frequency modulation.
[0010] What are needed are converters that correct AC power
factor.
[0011] What is needed are converters that meet or exceed class B
conducted EMI requirements.
[0012] What are needed are converters tolerant of lightning and
harsh thermal environments. The present invention addresses these
and more.
SUMMARY OF THE INVENTION
[0013] The main aspect of the present invention is to implement
converters having circuit strategies that make advantageous use of
individual and distributed NSME for the achievement of the key
performance enhancements disclosed herein.
[0014] Another aspect of the present invention is to provide unique
resonant tank circuit converter strategies with individual and
distributed NSME that make use of higher primary circuit voltage
excursions in the production of high frequency/high density
magnetic flux.
[0015] Another aspect of the present invention is a high energy
density single stage frequency controlled resonant tank converter
topology enabled by the use of individual and distributed NSME.
Another aspect of the present invention is to provide a converter
design that utilizes a FET drive technique consisting of an ultra
fast, low RDS on N-channel FET for charging the main FET gate and
an ultra fast P-channel transistor for discharging the main FET
gate.
[0016] Another aspect of the present invention is to provide
converters that incorporate efficient multiple "stressless" flyback
management techniques to rectify and critically damp excessive node
voltages across converter switches.
[0017] Another aspect of the present invention is to provide a
converter having core (flux) synchronized zero crossing frequency
modulation.
[0018] Another aspect of the present invention is to present a high
power factor to the AC line.
[0019] Another aspect of the present invention is to provide
[0020] Another aspect of the present invention is to provide
protection from high voltage (input line) transients.
[0021] Another aspect of the present invention is to combine
distributed magnetics advantageously with the other converter
aspects.
[0022] Another aspect of the present invention is active ripple
rejection provided by several high-gain high-speed isolated control
and feedback systems.
[0023] Other aspects of this invention will appear from the
following description and appended claims, reference being made to
the accompanying drawings forming a part of this specification
wherein like reference characters designate corresponding parts in
the several views.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 and 1A is a schematic diagram of a two-stage power
factor corrected AC to DC isolated output converter embodiment of
the invention.
[0025] FIG. 2 is a schematic diagram of a single stage DC to AC
converter embodiment with isolated output sub-circuit DCAC1.
[0026] FIG. 3 and 3A is a schematic diagram of a three stage AC to
DC isolated output converter embodiment of the invention.
[0027] FIG. 4 is a schematic diagram of a power factor corrected
single stage AC to DC converter sub-circuit ACDFPF.
[0028] FIG. 5 is a graph comparing typical winding currents in
inductance.
[0029] FIG. 6 is a schematic for a non-isolated low side switch
buck converter sub-circuit NILBK.
[0030] FIG. 7 is the preferred embodiment schematic for a tank
coupled single stage converter sub-circuit TCSSC.
[0031] FIG. 8 is a schematic for a tank coupled totem pole
converter sub-circuit TCTP.
[0032] FIG. 9 is a block diagram for a single stage non-isolated DC
to DC boost converter NILSBST.
[0033] FIG. 10 is a schematic for a two stage isolated DC to DC
boost controlled push-pull converter BSTPP.
[0034] FIG. 11 is a graph of permeability as a function of
temperature for typical prior art magnetic element material.
[0035] FIG. 12 is a graph of flux density as a function of
temperature for typical prior art magnetic element material.
[0036] FIG. 12A is a graph of magnetic element losses for various
flux densities and operating frequencies typical of prior art
magnetic element material.
[0037] FIG. 13 is a graph showing standard switching losses.
[0038] FIG. 14 is a graph showing lower switching losses of the
invention.
[0039] FIG. 15 is a graph showing the magnetizing curve (BH) for
the NSME material.
[0040] FIG. 16 is a graph of magnetic element losses for various
flux densities and operating frequencies of the NSME material.
[0041] FIG. 17 is a graph of permeability as a function of
temperature for the NSME.
[0042] FIG. 18 is a schematic representation of the boost NSME
sub-circuit PFT1.
[0043] FIG. 18A is a schematic representation of the NSME
sub-circuit PFT1A.
[0044] FIG. 18B is a schematic representation of the non-saturating
two terminal NSME sub-circuit BL1.
[0045] FIG. 18C is a schematic diagram of the NSME implemented as
distributed magnetic assembly PFT1D.
[0046] FIG. 19 is a schematic representation of the push-pull NSME
sub-circuit PPT1.
[0047] FIG. 19A is a schematic representation of the alternate
push-pull NSME sub-circuit PPT1A.
[0048] FIG. 20 is a schematic diagram of the NSME input transient
protection and line filter sub-circuit LL.
[0049] FIG. 21 is a schematic diagram of the alternate NSME input
transient protection and line filter sub-circuit LLA.
[0050] FIG. 22 is a schematic diagram of the AC line rectifier
sub-circuit BR.
[0051] FIG. 23 is a schematic diagram of the power factor
controller sub-circuit PFA.
[0052] FIG. 24 is a schematic diagram of the alternate power factor
correcting boost control element sub-circuit PFB.
[0053] FIG. 25 is a schematic diagram of the output rectifier and
filter sub-circuit OUTA.
[0054] FIG. 25A is a schematic diagram of an alternate rectifier
sub-circuit OUTB.
[0055] FIG. 25B is a schematic diagram of an alternate final output
rectifier and filter sub-circuit OUTBB.
[0056] FIG. 26 is a schematic diagram of the floating 18_Volt DC
control power sub-circuit CP.
[0057] FIG. 27 is a schematic diagram of the alternate floating
18_Volt DC push-pull control power sub-circuit CPA.
[0058] FIG. 28 is a schematic diagram of the over temperature
protection sub-circuit OTP.
[0059] FIG. 29 is a schematic diagram of the high-speed low
impedance buffer sub-circuit AMP, AMP1, AMP2 and AMP3.
[0060] FIG. 30 is a schematic diagram of the main switch snubber
sub-circuit SN.
[0061] FIG. 30A is a schematic diagram of the main switch
rectifying diode snubber sub-circuit DSN.
[0062] FIG. 31 is a schematic diagram of the alternate snubber
sub-circuit SNA.
[0063] FIG. 32 is a schematic diagram of the mirror snubber
sub-circuit SNB.
[0064] FIG. 33 is a schematic diagram of the pulse-width/Frequency
modulator sub-circuit PWFM.
[0065] FIG. 34 is an oscillograph of node voltages measured during
operation of sub-circuit PWFM (FIG. 33).
[0066] FIG. 35 is an oscillograph of the primary tank voltage
measured during operation of sub-circuit TCTP (FIG. 8).
[0067] FIG. 36 is a schematic diagram of the non-isolated 18-Volt
DC control power sub-circuit REG.
[0068] FIG. 37 is a schematic for a non-isolated high-side switch
buck converter sub-circuit HSBK.
[0069] FIG. 38 is a schematic for the low-side buck regulated
two-stage converter embodiment with isolated push-pull output
sub-circuit LSBKPP.
[0070] FIG. 39 is a schematic for an alternate isolated two-stage
low-side switch buck converter sub-circuit LSBKPPBR.
[0071] FIG. 40 is a schematic diagram of the over voltage feed back
sub-circuit IPFFB.
[0072] FIG. 40A is a schematic diagram of the non-isolated boost
output voltage feedback sub-circuit FBA.
[0073] FIG. 40B is a schematic diagram of the isolated output
voltage feedback sub-circuit IFB.
[0074] FIG. 40C is a schematic diagram of the alternate isolated
over voltage feedback sub-circuit IOVFB.
[0075] FIG. 41 is a schematic diagram of the non-isolated output
voltage feedback sub-circuit FBI.
[0076] FIG. 42 is a schematic diagram of an over voltage protection
sub-circuit OVP.
[0077] FIG. 42A is a schematic diagram of the isolated over voltage
feedback sub-circuit OVP1.
[0078] FIG. 42B is a schematic diagram of the over voltage
protection sub-circuit OVP2.
[0079] FIG. 42C is a schematic diagram of the isolated over voltage
feedback sub-circuit OVP3.
[0080] FIG. 43 is a schematic diagram of the Push-pull oscillator
sub-circuit PPG.
Before explaining the disclosed embodiments of the present
invention in detail, it is to be understood that:
[0081] The invention is not limited in its application to the
details of the particular arrangements shown or described, since
the invention is capable of other embodiments. since the invention
is capable of other embodiments.
[0082] The expression "distributed magnetic(s)" refers to the
configuration of multiple magnetic elements that share a single
series coupled primary winding to induce isolated output currents
from multiple series or parallel secondary windings.
[0083] Also, the terminology used herein is for the purpose of
description not limitation.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0084] In this and other descriptions contained herein, the
following symbols shall have the meanings attributed to them: "+"
shall indicate a series connection, such as resistor A in series
with resistor B shown as "A+B". ".parallel." Shall indicate a
parallel connection, such as resistor A in parallel with resistor B
shown as "A.parallel.B".
[0085] Referring first to FIG. 7, a schematic diagram of the
preferred embodiment of the invention.
[0086] FIG. 7 is a schematic of the preferred embodiment of a tank
coupled single stage converter sub-circuit TCSSC. Sub-circuit TCSSC
consists of resistor R20 and RLOAD, capacitor C10, transistors Q21
and Q11, sub-circuit CP (FIG. 26), sub-circuit PFT1 (FIG. 18),
sub-circuit OUTA (FIG. 25), sub-circuit AMP (FIG. 29), sub-circuit
IFB (FIG. 40B) and sub-circuit PWFM (FIG. 33).
1 Table number R20 1k ohms R61 2k ohms Q21 TST541 U12 4N29 Q11
IRFP460 C10 1.8 uf
[0087] TCSSC can be configured to operate as an AC-DC converter, a
DC-DC converter, a DC-AC converter, and an AC-AC converter.
Sub-circuit TCSSC consists of resistor R20 and RLOAD, capacitor
C10, switches Q11 and Q21, opto-isolator U12, sub-circuit PFT1
(FIG. 18), sub-circuit OUTA (FIG. 25), sub-circuit CP (FIG. 26),
sub-circuit AMP (FIG. 29), sub-circuit IFB (FIG. 40B) and
sub-circuit PWFM (FIG. 33). External power source VBAT connects to
pins DCIN+ and DCIN-. Source power may also be derived from
rectified AC line voltage such as FIG. 20 or FIG. 21 to form a
single stage power factor corrected AC to DC converter with
isolated output. From DCIN+ resistor R20 connects to sub-circuit CP
pin CP+, sub-circuit AMP pin GA+, U12 LED anode and to sub-circuit
PWFM pin PWFM+. Resistor R20 provides startup power to the
converter until the control supply regulator sub-circuit CP reaches
the desired 18-volt output. VBAT negative is the ground return node
connects to sub-circuit PWFM pin PWFM0, Q11 source, sub-circuit AMP
pin GA0, sub-circuit CP pin CT0, pin DCIN- and sub-circuit PFT1 pin
S1CT. Magnetic element winding node S1H of sub-circuit PFT1 is
connected to CP pin CT1A. Magnetic element winding node S1L of
sub-circuit PFT1 is connected to CP pin CT2A. Sub-circuit PWFM is
designed as a constant 50% duty-cycle variable frequency generator.
Sub-circuit PWFM Clock output pin CLK is connected to input of
buffer sub-circuit AMP pin GA1. The output of buffer sub-circuit
AMP pin GA2 is connected to the gate of Q11 and R21. Resistor R21
is connected to the cathode of U12 LED. The emitter of Q21 and
drain of Q11 is connected to sub-circuit PFT1 pin P1A. Pin P1B of
sub-circuit PFT1 is connected through tank capacitor C10 to node
DCIN+, Q21 collector and through resistor R61 to U12
phototransistor collector. The emitter of U12 phototransistor is
connected to the base of Q21. With PWFM pin CLK high transistor Q11
conducts charging capacitor C10 through NSME PFT1 from VBAT storing
energy in PFT1. Sub-circuit PWFM switches CLK low, Q11 turns "off".
With CLK low LED of U12 is turned "on" injecting base current into
Q21. With transistor Q21 "on" the tank circuit is completed,
allowing capacitor C10 to discharge into NSME PFT1 winding 100
(FIG. 18). Now the energy not transferred into the load is released
from NSME PFT1 into the now forward biased NPN switch Q21 back into
capacitor C10. Thus any energy not used by the secondary load
remains in the tank coupled primary circuit (winding 100). When the
switching occurs at the resonant frequency, high voltages oscillate
between C10 and winding 100 creating high flux density AC
excursions in PFT1. C10 and PFT1 exchange variable AC currents
whose magnitude is controlled by frequency modulation scheme IFB
and PWFM. The large primary voltage generates large, high frequency
biases in the NSME PFT1 thereby producing high flux density AC
excursions to be harvested by secondary windings 102 and 103 (FIG.
18) to support a load or rectifier sub-circuit OUTA. Magnetic
element winding node S2H of sub-circuit PFT1 is connected to OUTA
pin C7B. Magnetic element winding node S2L of sub-circuit PFT1 is
connected to OUTA C8B. Magnetic element winding node S2CT of
sub-circuit PFT1 is connected to OUTA pin OUT-. Node OUT- is
connected to RLOAD, pin B- and to sub-circuit IFB pin OUT-.
Rectified power is delivered to pin OUT+ of OUTA and is connected
to RLOAD, pin B+ and to sub-circuit IFB pin OUT+. Sub-circuit IFB
provides the isolated feedback signal to the sub-circuit PWFM.
Frequency control pin FM1 of sub-circuit PWFM is connected to
sub-circuit IFB pin FBE. Internal reference pin REF of sub-circuit
PWFM is connected to sub-circuit IFB pin FBC. PWFM is designed to
operate at the resonate frequency of the tank (2*pi*(square root
(Co*inductance of 100 (FIG. 18)). When sub-circuit IFB senses the
converter output is at the target voltage, current from PWFM pin
REF is injected into FM1. Injecting current into FM1 commands the
PWFM to a lower clock frequency pin CLK. Driving the tank out of
resonance reduces the amount of energy added to the tank thus
reducing the converter output voltage. In the event the feedback
signal from IFB commands the PWFM off or 0 Hz, i.e.: at no load,
all primary activity stops. The input current from VBAT may be
steady state or variable DC. When TCSSC is operated from rectified
AC (sub-circuit LL FIG. 20), high input (line) power factor and
input transient protection is achieved. The primary and secondary
currents of PFT1 are sinusoidal and free of edge currents of PFT1
are sinusoidal and free of edge transitions making the converter
very quiet. In addition the switches Q11 and Q21 are never exposed
to the large circulating voltage induced in the tank (See FIG. 35).
This allows the use of lower voltage switches in the design thereby
reducing losses and increasing the MTBF. Sub-circuit TCSSC takes
advantage of the desirable properties of the NSME in this converter
topology. TCSSC is well suited for implementation with distributed
NSME PFT1D (FIG. 18C). This combination exemplifies how distributed
magnetics enable advantageous high voltage converter design
variations that support form factor flexibility and multiple
parallel secondary outputs from series coupled voltage divided
primary windings across multiple NSME. This magnetic strategy is
useful in addressing wire/core insulation, form factor and
packaging limitations, circuit complexity and manufacturability.
These converter strategies are very useful for obtaining isolated
high current density output from a high voltage low current series
coupled primary. Adjusting the secondary turn's ratio allows TCSSC
to generate very large AC or DC output voltages as well as
low-voltage high current outputs.
Additional Embodiments
[0088] FIG. 1 and 1A is a schematic diagram of a two stage power
factor corrected AC to DC converter. The invention is comprised of
line protection filter sub-circuit LL (FIG. power factor corrected
regulated boost stage with sub-circuits PFA2 (FIG. 23), snubber
sub-circuit SN (FIG. 30), magnetic element sub-circuit PFT1 (FIG.
18), sub-circuit CP (FIG. 26), buffer sub-circuit AMP (FIG. 29),
over temperature sub-circuit OTP (FIG. 28), over voltage feedback
sub-circuit IPFFB (FIG. 40) and voltage feedback sub-circuit IFB
(FIG. 40B). Start up resistor R2, filter capacitor C1, PFC
capacitor C2, flyback diode D4, switch transistor Q1, hold up
capacitors C17 and C16, and resistor R17. An efficient push-pull
isolation stage with sub-circuits CPA (FIG. 27), PPG (FIG. 43),
AMP1 (FIG. 29), AMP2 (FIG. 29), snubber sub-circuits SNB (FIG. 32)
and SNA (FIG. 31), resistor Rload, transistors Q6 and Q9, magnetic
element PPT1 (FIG. 19), and OUTA (FIG. 25).
2 Table Element Value/part number Cl 0.01 uf C2 1.8 uf R2 100k ohms
D4 8A,600 V Q1 IRFP 460 C17 100 uf C16 100 uf R17 375k ohms Q6 FS
14SM-18 A Q9 FS 14SM-18 A
[0089] In the two-stage converter the primary side voltage to the
second push-pull output stage is modulated by the power factor
corrected input (boost) stage. Each stage can comprise of
individual and distributed NSME. A graph of B-H hysteresis for the
non-saturating magnetics is set forth in FIG. 15. Although the
following description is in terms of particular converter
topologies, i.e., flyback controlled primary and constant duty
cycle push pull secondary, number of outputs, the style, and
arrangement of the several topologies are offered by way of
example, not limitation. In addition non-saturating magnetics BL1,
PFT1, and PPT1 may be implemented as distributed NSME. As an
example PFT1 is shown as a distributed magnetic PFT1A (FIG. 18C).
Distributed magnetics enable advantageous high voltage converter
design variations that support form factor flexibility and multiple
parallel secondary outputs from series coupled voltage divided
primary windings across multiple NSME. The negative of the hold-up
capacitor(s) [C171.parallel.C16] is connected to bridge positive.
This allows the rectified line voltage to be excluded from the
boost voltage in the hold-up capacitor(s). This, in turn, allows
direct regulation of the push-pull stage from the boost (PFC)
stage. This eliminates the typical PWM control of the oversized
thermally derated transformer and many sub-circuit components from
the known art. AC line is connected to sub-circuit LL (FIG. 20)
between pins LL1 and LL2. AC/earth ground is connected to node LL0.
The filtered and voltage limited AC line appears on node/pin LL5 of
sub-circuit LL and connected to node BR1 of bridge rectifier
sub-circuit BR (FIG. 22). The neutral/AC return leg of the filtered
and voltage limited AC appears on pin LL6 of sub-circuit LL is
connected to input pin BR2 of BR. The line voltage is full-wave
rectified and is converted to a positive haversine appearing on
node BR+ of sub-circuit BR (FIG. 22). Start up resistor R2 connects
BR+ to sub-circuit CP pin CP+. Node CP+ connects to pins PFA+ of
control element sub-circuit PFA (FIG. 23) and over temperature
switch sub-circuit OTP (FIG. 28) pin GAP. Resistor R2 provides
start up power to the control element until the rectifier/regulator
CP is at full output. Node S1H from PFT1 is connected to node PFVC
of sub-circuit PFA. The zero crossings of the core are sensed when
the voltage at S1H is at zero. The core zero crossings are used to
reset the PFC and start a new cycle. The positive node of the DC
side of bridge BR+ is connected through capacitor C2 to BR-. C2 is
selected for various line and load conditions to de-couple
switching current from the line improving power factor while
reducing line harmonics and EMI. Primary of NSME sub-circuit PFT1
(FIG. 18) pins P1B and S2CT connects to pin SNL1 of snubber
sub-circuit SN (FIG. 30), to sub-circuit BR pin BR+ and connects to
pin BR+ (FIG. 1A). The return line for the rectified AC power BR-
is connected to the following pins: BR- of sub-circuit BR, PFA pin
BR-, sub-circuit AMP pin GA0, output switch Q1 source, capacitor
C2, sub-circuit CP pin CT0 sub-circuit PFT1 pin SICT and CT20
through EMI filter capacitor C1 to earth ground node LL0. Pin BR+
from FIG. 1 is connected to FIG. 1A sub-circuits CPA pin SN pin
SNL1, sub-circuit PFT1 pin P1B, and sub-circuit PFT1 pin S2CT. Pin
BR+ continues to FIG. 1A connecting to sub-circuit CPA pin CT20,
PPG (FIG. 43) pin PPG0, sub-circuit AMP1 pin GA0, sub-circuit AMP2
pin GA0, sub-circuit IPFFB pin PF-, Capacitor
[C16.parallel.C17.parallel.resistor R17], transistor Q6 source,
transistor Q9 source, sub-circuit SNA pin SNA2 and sub-circuit SNB
pin SNB2. The drain of output switch Q1 is connected to diode D4
anode, sub-circuit SNB pin SNL2, and sub-circuit PFT1 pin P1A and
sub-circuit SN pin SNL2. Snubber network SN reduces the high
voltage stress to Q1 until flyback diode D4 begins conduction. Line
coupled, power factor corrected boost regulated output voltage of
the AC to DC converter stage (FIG. 1) appears on node PF+. Addition
efficiency may be realized by connecting sub-circuit DSN (FIG. 30A)
in parallel with D4. The regulated boost output PF+ connects to the
following: sub-circuit SN pin SNOUT, sub-circuit DSN pin SNOUT and
diode D4 cathode. Node PF+ also connects on FIG. 1A to capacitors
[C16.parallel.C17.parallel.R17], sub-circuit IPFFB (FIG. 40) pin
PF+, sub-circuit PPT1 (FIG. 19) pin P2CT, snubber sub-circuit SNA
(FIG. 31) pin SNA3, and snubber SNB (FIG. 32) pin SNB3. Magnetic
element winding pin S1H of sub-circuit PFT1 is connected to CP pin
CT1A and pin PFVC of sub-circuit PFA. Magnetic element winding node
S1L of sub-circuit PFT1 is connected to CP pin CT2A. Magnetic
element winding node S2H of sub-circuit PFT1 is connected to pin 10
FIG. 1A then to CPA pin CT1B. Magnetic element winding node S2L of
sub-circuit PFT1 is connected to pin 12 FIG. 1A then to CPA pin
CT2B. Sub-circuit PFA using the AC line phase, load voltage, and
magnetic element feedback, generates a command pulse PFCLK. Pin
PFCLK of sub-circuit PFA (FIG. 23) is connected to the input of
buffer amplifier pin GA1 of sub-circuit AMP1 (FIG. 29). Buffered
high-speed gate drive output pin GA2 of sub-circuit AMP is
connected to gate of switch FET Q1. The buffering provided by AMP
shortens switch Q1 ON and OFF times greatly reducing switch losses
(see FIG. 13 & 14). The source of Q1 with pin GA0 is connected
to return node BR-. Power to sub-circuit AMP is connected to pin
GA+ from sub-circuit OTP pin TS+. Thermal switch THS1 is connected
to Q1. In the event the case of Q1 reaches approximately 105 C.
THS1 opens removing power to sub-circuit AMP, safely shutting down
the first (input) stage. Normal operation resumes after the switch
temperature drops 20-30 deg. C. closing THS1. Drain of output
switch Q1 is connected to primary winding pin P1A of non-saturating
magnetic sub-circuit PFT1 (FIG. 18) and to pin SNL2 of snubber
sub-circuit SN (FIG. 30). Reference voltage from PFC sub-circuit
PFA pin PFA2 is connected to feedback networks sub-circuit IPFFB
pin FBC and to sub-circuit IFB pin FBC. Control current feedback
networks is summed at node PF1 of sub-circuit PFA. Pin PF1 is
connected to feed back networks sub-circuit IPFFB pin FBE and to
sub-circuit IFB pin FBE. Constant frequency/duty-cycle
non-overlapping two-phase generator sub-circuit PPG (FIG. 43 1A)
generates the drive for the push-pull output stage. Phase one
output pin PH1 is connected to sub-circuit AMP1 in GA1, second
phase output pin PH2 is connected to sub-circuit AMP2 pin GA1.
Output of amplifier buffer sub-circuit AMP1 pin GAP2 connects to
gate of push-pull output switch Q6. Output of amplifier buffer
sub-circuit AMP2 pin GAP2 connects to gate of push-pull output
switch Q9. The buffering currents from AMP1 and AMP2 provide fast,
low impedance critically damped switching to Q6 and Q9 greatly
reducing ON-OFF transition time and switching losses. Regulated
18-volt power from sub-circuit CPA (FIG. 1A) pin CP2+ is connected
to amplifier buffer sub-circuit AMP1 pin GA+, amplifier buffer
sub-circuit AMP2 pin GA+ and sub-circuit PPG pin PPG+. Drain of
transistor Q6 is connected to snubber network sub-circuit SNB pin
SNB1 and to non-saturating center tapped primary magnetic element
sub-circuit PPT1 pin P2H. Drain of transistor Q9 is connected to
snubber network sub-circuit SNA (FIG. 31) pin SNA1 and sub-circuit
PPT1 pin P2L. Source of transistor Q6 is connected to snubber
network sub-circuit SNB pin SNB2, transistor Q9 source, sub-circuit
SNA pin SNA2 and to return node BR+. Isolated output of NSME
sub-circuit PPT1 pin SH connects to Pin C7B of rectifier
sub-circuit OUTA (FIG. 25A), pin SL connects to sub-circuit OUTA
C8B. Center tap of PPT1 pin SCT is the output return or negative
node OUT- it connects to sub-circuit OUTA pin OUT- and sub-circuit
IFB (FIG. 40B) pin OUT- and RLOAD. Converter positive output from
sub-circuit OUTA pin OUT+ is connected to RLOAD and sub-circuit IFB
pin OUT+. FIG. 1 elements LL1, BR, PFA, AMP, Q1, IPFFB, IFB and
PFT1 (input stage) perform power factor corrected AC to DC
conversion. The regulated high voltage output of this converter
supplies the efficient fixed frequency/duty-cycle push-pull stage
comprising PPG, AMP1, AMP2, Q6, Q9, PPT1 and OUTA (FIG. 1A).
Magnetic element sub-circuit PPT1 provides galvanic isolation and
minimal voltage overshoot and ripple in the secondary thus
minimizing filtering requirements of the rectifier sub-circuit
OUTA. Five volt reference output from sub-circuit PFA pin PFA2
connects to pin 15 then to FIG. 1A sub-circuit IPFFB pin FBC and to
sub-circuit IFB pin FBC. Pulse width control input from sub-circuit
PFA pin PF1 connects to pin 14 then to FIG. 1A sub-circuit IPFFB
pin FBE and to sub-circuit IFB pin FBE. Sub-circuit IFB provides
high-speed feedback to the AC DC converter, the speed of the boost
stage provides precise output voltage regulation and active ripple
rejection. In the event of sudden line or load changes, sub-circuit
IPFFB corrects the internal boost to maintain regulation at the
isolated output. Remote load sensing and other feedback schemes
known in the art may be implemented with sub-circuit IPFFB. This
configuration provides power factor corrected input transient
protection, rapid line-load response, excellent regulation,
isolated output and quiet efficient operation at high
temperatures.
[0090] FIG. 2 is a schematic diagram of an embodiment of a DC to AC
converter. The invention DCAC1 is an efficient push-pull converter.
Comprised of sub-circuits PPG (FIG. 43), AMP1 (FIG. 29), AMP2 (FIG.
29), SNB (FIG. 32), SNA (FIG. 31), PPT1 (FIG. 19) and OUTA (FIG.
25), switches Q6 and Q9.
3 Table Element Value/part number Q6 FS 14SM-18 A Q9 FS 14SM-18
A
[0091] Converter ACDC1 accepts variable DC voltage and efficiently
converts it to a variable AC voltage output at a fixed frequency.
Variable frequency operation may be achieved by simple changes to
PPG. In this embodiment fixed frequency operation is required. The
magnetic element comprises non-saturating magnetics. A graph of B-H
hysteresis for the non-saturating magnetics is set forth in FIG.
15. Variable DC voltage is applied to pin DC+. The pin DC+ connects
to the following, sub-circuit PPT1 (FIG. 19) pin P2CT, snubber
sub-circuit SNA (FIG. 31) pin SNA3, and snubber SNB (FIG. 32) pin
SNB3. Constant frequency non-overlapping two-phase generator
sub-circuit PPG (FIG. 43) generates the drive for the push-pull
output switches. Phase one output pin PH1 is connected to
sub-circuit AMP1 pin GA1, the second phase output pin PH2 is
connected to sub-circuit AMP2 pin GA1. Output of amplifier buffer
sub-circuit AMP1 pin GAP2 connects to gate of push-pull output
switch Q6. Output of amplifier buffer sub-circuit AMP2 pin GAP2
connects to gate of push-pull output switch Q9. The buffering
provided by AMP1 and AMP2 shortens switch Q1 ON and OFF times
greatly reducing switching losses (See FIG. 13 and 14). External
regulated 18-volt power from pin P18V connected to amplifier buffer
sub-circuit AMP1 pin GA+, amplifier buffer sub-circuit AMP2 pin GA+
and sub-circuit PPG pin PPG+. Drain of transistor Q6 is connected
to snubber network sub-circuit SNB pin SNB1 and to non-saturating
center tapped primary magnetic element sub-circuit PPT1 pin P2H.
Drain of transistor Q9 is connected to snubber network sub-circuit
SNA (FIG. 31) pin SNA1 and sub-circuit PPT1 pin P2L. Source of
transistor Q6 is connected to snubber network sub-circuit SNB pin
SNB2, transistor Q9 source, sub-circuit SNA pin SNA2, sub-circuit
AMP1 pin GA0, sub-circuit AMP2 pin GA0, sub-circuit PPG pin PPG0,
and to return pin DC-. AC output of NSME sub-circuit PPT1 pin SH
connects to Pin ACH, pin SL connects to pin ACL. Center tap of PPT1
pin SCT is connected to pin AC0. Magnetic element sub-circuit PPT1
provides galvanic isolation and minimal voltage overshoot in the
secondary thus minimizing filtering requirements if a rectifier
assembly is attached. Sub-circuit DCAC1 may be used as a
stand-alone converter or as a fast quiet efficient stage in a multi
stage converter system. Sub-circuit DCAC1 achieves isolated output,
quiet operation, efficient conversion, and operation at high and
low temperatures.
[0092] FIG. 3 and 3A is a three-stage version of the present
invention. The arrangement is comprised of an AC-DC or DC-DC boost
converter stage, DC-DC forward converter stage, and a push-pull
stage. This system reduces losses by combining low current buck
regulation, buffered switching, rectified snubbering, and NSME in
each stage. A power factor corrected boost stage is used to assure
that any load connected to the converter looks like a resistive
load to the AC line, eliminating undesirable harmonic and
displacement currents in the AC power line. NSME having a lower
permeability compared to the prior art are used to minimize
magnetizing losses, improve coupling efficiency, minimize magnetic
element heating, eliminate saturated core current spikes/gap
leakage, reduce parts count, reduce thermal deterioration, and
increase MTBF (mean time before failure). The invention also uses
an emitter follower circuit with a high speed switching FET to slew
the main FET gate rapidly. The use of non-saturating magnetics
allows operation at higher voltages, which proportionally lowers
current further reducing switch, magnetic element, and conductor
losses due to I.sup.2R heating. High voltage FET switches have the
added benefit of lower gate capacitance, which translates to faster
switching. At turn on, the n-channel gate drive FET quickly charges
the main FET gate. At turn off, a PNP Darlington transistor switch
quickly discharges the main FET gate. The flyback effect in the PFC
stage is managed by use of rectifying RC networks positioned across
the output diode with an additional capacitor coupled diode across
the switched magnetic element to decouple and further dampen the
inductive flyback.
[0093] FIG. 3 and FIG. 3A is a schematic diagram of a three stage
AC to DC converter. FIG. 3 and 3A is a three-stage version of the
present invention. The arrangement is comprised of an AC-DC or
DC-DC boost converter stage, DC-DC forward converter stage, and a
push-pull stage. This system reduces losses by combining low
current buck regulation, buffered switching, rectified snubbering,
and NSME in each stage. A power factor corrected boost stage is
used to assure that any load connected to the converter looks like
a resistive load to the AC line, eliminating undesirable harmonic
and displacement currents in the AC power line. NSME having a lower
permeability compared to the prior art are used to minimize
magnetizing losses, improve coupling efficiency, minimize magnetic
element heating, eliminate saturated core current spikes/gap
leakage, reduce parts count, reduce thermal deterioration, and
increase MTBF (mean time before failure). The invention also uses
an emitter follower circuit with a high speed switching FET to slew
the main FET gate rapidly. The use of non-saturating magnetics
allows operation at higher voltages, which proportionally lowers
current further reducing switch, magnetic element, and conductor
losses due to I.sup.2R heating. High voltage FET switches have the
added benefit of lower gate capacitance, which translates to faster
switching. At turn on, the n-channel gate drive FET quickly charges
the main FET gate. At turn off, a PNP Darlington transistor switch
quickly discharges the main FET gate. The flyback effect in the PFC
stage is managed by use of rectifying RC networks positioned across
the output diode with an additional capacitor coupled diode across
the switched magnetic element to decouple and further dampen the
inductive flyback. The invention is comprised of a power factor
corrected regulating boost stage with line protection filter
sub-circuit LL1 (FIG. 21) and full-wave rectifier sub-circuit BR
(FIG. 22) and capacitors C1 and C2. Sub-circuits PFB (FIG. 24),
resistor R2, rectifier CP (FIG. 26), magnetic element PFT1 (FIG.
18), over temperature protection OTP (FIG. 28) snubber SN (FIG. 30)
gate buffer AMP (FIG. 29), switch transistors Q1, flyback diode D4,
holdup capacitors C17 and C16, bleed resistor R17, and voltage
feedback sub-circuit FBA (FIG. 40A). An efficient second
pre-regulating buck stage with sub-circuits PWFM (FIG. 33), current
sense resistor R26, rectifier CPA (FIG. 27), magnetic element BL1,
(FIG. 18B), over voltage protection OVP (FIG. 42), IPFFB (FIG. 40)
gate buffer AMP3 (FIG. 29), switch transistor Q2, flyback diode
D70, storage capacitor C4, and voltage feedback sub-circuit IFB
(FIG. 40B).
[0094] An efficient third push-pull isolation stage with
sub-circuits CPA (FIG. 27), two-phase generator PPG (FIG. 43), gate
buffers AMP1 (FIG. 29) and AMP2 (FIG. 29), switch transistors Q6,
and Q9, snubbers SNA (FIG. 31) and SNB (FIG. 32), magnetic element
PPT1 (FIG. 19) and rectifier OUTA (FIG. 25).
4 FIG. 3 3A Table Element Value/part number C1 .01 uf C2 1.8 uf R2
100k ohms D4 STA1206 DI R17 375k ohms Q1 IRFP460 C16 100 uf C17 100
uf R26 .05 ohms D70 STA1206 DI Q2 IRFP460 C4 10 uf Q6 FS14Sm-18 A
Q9 FS14Sm-18 A
[0095] AC line is connected to sub-circuit LLA (FIG. 21) between
pins LL1 and LL2. AC/earth ground is connected to node LL0. The
filtered and voltage limited AC line appears on node/pin LL5 of
sub-circuit LLA and connected to node BR1 of bridge rectifier
sub-circuit BR. The neutral/AC return leg of the filtered and
voltage limited AC appears on pin LL6 of sub-circuit LL is
connected to input pin BR2 of BR. The line voltage is full-wave
rectified and is converted to a positive haversine appearing on
node BR+ of sub-circuit BR. Start up resistor R2 connects BR+ to
sub-circuit CP pin CP+. Node CP+ connects to pins PFA+ of control
element sub-circuit PFB and over temperature switch sub-circuit OTP
pin GAP. Resistor R2 provides start up power to the control element
until the regulator CP is at full output. Node S1H from PFT1 is
connected to pin 31 (FIG. 3) then to pin CT1A of sub-circuit CP and
pin PFVC of sub-circuit PFB. The zero crossing of the core bias are
sensed when the voltage at S1H is at zero relative to BR-. The core
zero crossings are used to reset the PFC and start a new cycle. The
positive node of the DC side of bridge BR+ is connected through
capacitor C2 to BR-. Capacitor C2 is selected for various line and
load conditions to de-couple switching current from the line
improving power factor. Sub-circuit BR pin BR+ connects to pin SNL1
of snubber sub-circuit SN, sub-circuit PFB pin BR+ and pin BR+
(FIG. 3A) then to primary of NSME sub-circuit PFT1 pin P1B and to
sub-circuit OVP pin BR+. The return line for the rectified AC power
is connected to the following pins; BR- of sub-circuit BR,
sub-circuit PFT1 pin S1CT, PFC sub-circuit PFB pin BR-, sub-circuit
FBA pin BR-, capacitor C2, sub-circuit CP pin CT0, sub-circuit
IPFFB pin FBE, and through EMI filter capacitor C1 to earth ground
node LL0. Node BR- continues to FIG. 3A connecting to R26,
capacitors [C16.parallel.C17.parallel.R17], sub-circuit OVP pin
BR-, sub-circuit PWFM pin PWFM0, sub-circuit AMP3 pin GA0, switch
Q2 source. Floating ground node PF- is connected to magnetic
element sub-circuit PFT1 pin S2CT, rectifier sub-circuit CPA pin
CT20, generator sub-circuit PPG (FIG. 43) pin PPG0, sub-circuit
AMP1 pin GA0, sub-circuit AMP2 pin GA0, capacitor C4, magnetic
element BL1, pin, transistor Q6 source, transistor Q9 source,
sub-circuit SNA pin SNA2 sub-circuit SNB pin SNB2, pin PF-FIG. 3
then to sub-circuit IPFFB pin PF-. Drain of output switch Q1 is
connected to diode D4 anode, sub-circuit SN pin SNL2, then to pin
34 of FIG. 3A then to sub-circuit PFT1 pin P1A. Snubber SN reduces
the high voltage stress to Q1 until flyback diode D4 begins
conduction. Additional rectification efficiency and protection is
achieved by adding sub-circuit DSN (FIG. 30A) across flyback diode
D4. Feedback corrected boost output voltage of the power factor
corrected AC to DC converter stage appears across nodes PF+ and
PF-. The regulated 385-volt boost output node PF+ connects to the
following; sub-circuit SN pin SNOUT, diode D4 cathode, sub-circuit
IPFFB (FIG. 40) pin PF+, sub-circuit FBA pin PF+, then to pin PF+
of FIG. 3A, capacitors [C16.parallel.C17.parallel.R17], magnetic
element sub-circuit PTT1 (FIG. 19) pin P2CT, snubber sub-circuit
SNA (FIG. 31) pin SNA3, and snubber SNB (FIG. 32) pin SNB3,
sub-circuit OVP pin PF+, capacitor C4 and diode D70 cathode.
Magnetic element winding node S1H of sub-circuit PFT1 is connected
to pin 31 FIG. 3 then to sub-circuit CP pin CT1A and pin PFVC of
sub-circuit PFB. Magnetic element winding node S1L of sub-circuit
PFT1 is connected to pin 33 FIG. 3 then to sub-circuit CP pin CT2A.
Magnetic element winding node S2H of sub-circuit PFT1 is connected
to CPA pin CT1B. Magnetic element winding node S2L of sub-circuit
PFT1 is connected to CP pin CT2B. Sub-circuit PFB using feedback
from the phase of the AC line, Q1 switch current, magnetic bias
first stage and output voltage feedback generates a command pulse
on pin PFCLK. Pin PFCLK of sub-circuit PFB (FIG. 24) is connected
to the input of buffer AMP amplifier pin GA1 of sub-circuit AMP1.
Buffered high-speed low impedance gate drive output pin GA2 of
sub-circuit AMP is connected to gate of switch FET Q1. The
buffering provided by AMP shortens switch Q1 "ON" and "OFF" times
greatly reducing switch losses (See FIGS. 13 and 14). The source of
Q1 is connected to sub-circuit AMP pin GA0, pin 35 of FIG. 3A then
to current sense resistor R26 connected to return node BR-. The
voltage developed across R26 is fed back to PFB pin PFSC. This
signal is used to protect the switch by reducing the pulse width in
response to a low line or high load induced over current fault. The
return line of sub-circuit FBA pin BR- is connected to node BR- and
to pin BR- of sub-circuit PFB. This feedback is non-isolated;
network values are selected for the first stage to develop a
385-Volt output at PF+. Sub-circuit feedback network FBA (FIG. 40A)
pin PF1 is connected to sub-circuit PFB pin PF1. Controller PFB
modulates PFCLK signal to maintain a substantially constant
385-voltage at PF+ independent of line and load conditions. In the
event of a component failure in sub-circuit FBA the PBF may command
the converter to very high voltages. Sub-circuit OVP monitors the
first stage boost in the event it exceeds 405-volts OVP will clamp
the output of sub-circuit BR causing fuse F1 in sub-circuit LLA to
open. An alternate over voltage network OVP1 (FIG. 42A) may replace
OVP clamping the 18-volt control power stopping the boost action of
the converter without opening the fuse. Sampled converter output at
node from sub-circuit FBA pin PF1 is connected to sub-circuit PFB
pin PF1. The haversine on BR+ is used with an internal multiplier
by PFB to generate variable width control pulses on pin PFCLK. The
high frequency modulation of switch Q1 makes the load/converter
appear resistive to the AC line. Over temperature protection
sub-circuit OTP pin TS+ is connected to sub-circuit AMP pin GA+.
Thermal switch THS1 is connected to Q1. In the event Q1 reaches
approximately 105 C. THS1 opens removing power to sub-circuit AMP,
safely shutting down the first stage. Normal operation resumes
after the temperature decreases 20-30 C. closing THS1. The second
stage is configured as a buck stage. It accepts the 385-Volt output
of the first stage. By employing a second floating reference node
PF- energy storage element capacitor C4 the voltage to the final
push-pull stage may be regulated with minimal loss. Power from
sub-circuit CP pin CP18V+ is connected to pin 30 of FIG. 3A then to
sub-circuit PWFM (FIG. 33) pin PWM+ and AMP3 pin GA+. Feedback
current from sub-circuit IPFFB pin FBC is connected to pin 36 FIG.
3A then to sub-circuit IFB pin FBC and sub-circuit PWFM pin PF1.
Sub-circuit IPFFB only shunts current from this node if the output
of the second stage is greater than 200-volts. When the converter
reaches its designed output voltage, IFB shunts current from PWFM
pin PF1 signaling PWFM to reduce the pulse width on pin PWMCLK.
Sub-circuit AMP3 input pin is connected to sub-circuit PWFM pin
PWMCLK. Output of AMP3 buffer pin GA2 is connected to gate of
switch Q2. Drain of Q2 is connected to anode of D70 and
non-saturating magnetic sub-circuit BL1, pin P2B (FIG. 18B).
Turning on switch Q2 charges C4 also storing energy in magnetic
element BL1. Releasing switch Q2 allows energy stored in magnetic
element BL1, to charge C4 through flyback diode D70. Larger pulse
widths charge C4 to larger voltages thus efficiently blocking part
of the first stage voltage to the final push-pull stage. This
action provides regulated voltage to the final converter stage. The
third and final push-pull (transformer) converter stage provides
the galvanic isolation, filtering and typically converts the
internal high voltage bus to a lower regulated output voltage. The
efficient push-pull stage produces alternating magnetizing currents
in the NSME for maximum load over core mass. Constant frequency
non-overlapping two-phase generator sub-circuit PPG (FIG. 43)
generates the drive for the push-pull output stage. Phase one
output pin PH1 is connected to sub-circuit AMP1 pin GA1, output pin
PH2 is connected to sub-circuit AMP2 pin GA1. Output of amplifier
buffer sub-circuit AMP1 pin GAP2 connects to gate of push-pull
output switch Q6. Output of amplifier buffer sub-circuit AMP2 pin
GAP2 connects to gate of push-pull output switch Q9. The buffering
provided by AMP1 and AMP2 shortens switch Q1 ON and OFF times
greatly reducing switching losses. (See FIG. 13 and 14) Regulated
18-volt power from sub-circuit CPA pin CP18+ is connected to
amplifier buffer sub-circuit AMP1 pin GA+, amplifier buffer
sub-circuit AMP2 pin GA+ and sub-circuit PPG pin PPG+. Drain of
transistor Q6 is connected to snubber network sub-circuit SNB pin
SNB1 and to non-saturating center tapped primary magnetic element
sub-circuit PPT1 pin P2H. Drain of transistor Q9 is connected to
snubber network sub-circuit SNA (FIG. 31) pin SNAL and sub-circuit
PPT1 pin P2L. Return node PF- connects source of transistor Q6 to
snubber network sub-circuit SNB pin SNB3, transistor Q9 source,
sub-circuit SNA pin SNA3 and to return node GND2. Output of NSME
sub-circuit PPT1 pin SH connects to pin C7B of rectifier
sub-circuit OUTA (FIG. 25), pin SL connects to C8B. Center tap of
PPT1 pin SCT is the output return or negative node OUT- it connects
to sub-circuit pin OUT- and sub-circuit IFB pin OUT- and RLOAD.
Supply positive output from sub-circuit OUTA pin OUT+ is connected
to RLOAD and sub-circuit IFB pin OUT+. Elements LL1, BR, PFA, AMP,
Q1, IPFFB, IFB and PFT1 provide power factor corrected AC to DC
conversion and DC output regulation. The regulated high voltage
output of this converter is used to power the efficient fixed
frequency push-pull stages PPG, AMP1, AMP2, Q6, Q9, PPT1 and OUTA.
Magnetic element sub-circuit PPT1 provides galvanic isolation and
minimal voltage overshoot in the secondary thus minimizing
filtering requirements of the rectifier sub-circuit OUTA.
Sub-circuit IFB provides high-speed feedback to the AC DC
converter, the speed of the boost stage provides precise output
voltage regulation and active ripple rejection. In the event of a
sudden line or load changes sub-circuit IPFFB compensates the
internal boost. This system reduces losses by focusing output
control in the middle (low current) stage of the converter and by
using non-saturating magnetics, buffered switching, and rectifying
snubbers throughout each stage. The combined improvements translate
to higher system efficiencies, higher power densities, lower
operating temperatures, and, improved thermal tolerance thereby
reducing or eliminating the need for forced air-cooling per unit
output. The non-saturating magnetic properties are relatively
insensitive to temperature (see FIG. 17), thus allowing the
converter to operate over a greater temperature range. In practice,
the operating temperature for the Kool Mu NSME is limited to 200 C.
by wire/core insulation; the non-saturating magnetic material
remains operable to near its Curie temperature of 500 C. This
configuration provides power factor corrected input transient
protection, rapid line-load and ripple compensation, excellent
output regulation, output isolation and quiet efficient operation
at high temperatures.
[0096] FIG. 4 is a schematic diagram sub-circuit ACDCPF.
[0097] FIG. 4 is a schematic diagram of a power factor corrected
single stage AC to DC converter sub-circuit ACDCPF. The invention
is comprised of line protection filter sub-circuit LL (FIG. 20) and
full-wave rectifier sub-circuit BR (FIG. 22). A power factor
corrected regulated boost stage with sub-circuits PFB (FIG. 24),
snubber sub-circuit SN (FIG. 30), magnetic element sub-circuit
PFT1A (FIG. 18A), sub-circuit CP (FIG. 26), buffer sub-circuit AMP
(FIG. 29), over temperature sub-circuit OTP (FIG. 28), and voltage
feedback sub-circuit FBA (FIG. 40A). Start up resistor R2, filter
capacitor C1, PFC capacitor C2, flyback diode D4, switch transistor
Q1, hold up capacitors C17 and C16, and resistor R17.
5 Table Element Value/part number Cl .01 uf C2 1.8 uf R2 100k ohms
R26 0.05 ohms Q1 IRFP 460 D4 STA1206 DI C17 100 uf C16 100 uf R17
375k ohms
[0098] AC line is connected to sub-circuit LL (FIG. 20) between
pins LL1 and LL2. AC/earth ground is connected to node LL0. The
filtered and voltage limited AC line appears on node/pin LL5 of
sub-circuit LL1 and connected to node BR1 of bridge rectifier
sub-circuit BR (FIG. 22). The neutral/AC return leg of the filtered
and voltage limited AC appears on pin LL6 of sub-circuit LL is
connected to input pin BR2 of BR. The line voltage is full-wave
rectified and is converted to a positive haversine appearing on
node BR+ of sub-circuit BR (FIG. 22). Start up resistor R2 connects
BR+ to sub-circuit CP pin CP+. Node CP+ connects to pins PFA+ of
power factor controller sub-circuit PFA (FIG. 24) and over
temperature switch sub-circuit OTP (FIG. 28) pin GAP. Resistor R2
provides start up power to the control element until the rectifier
and regulator CP is at full output. Node S1H from PFT1A is
connected to node PFVC sub-circuit PFB. The zero crossing of the
core bias are sensed when the voltage at S1H is at zero. The core
zero crossings are used to reset the PFC and start a new cycle. The
positive node of the DC side of bridge BR+ is connected through
capacitor C2 to BR-. C2 is selected for various line and load
conditions to de-couple switching current from the line improving
power factor. Primary of NSME sub-circuit PFT1A (FIG. 18A) pin P1B
connects to pin SNL1 of snubber sub-circuit SN (FIG. 30),
sub-circuit PFB pin BR+ and connects to node BR+. The return line
for the rectified AC power BR- is connected to the following pins;
BR- of sub-circuit BR, sub-circuit PFB pin BR-, sub-circuit AMP pin
GA0, sense resistor R26, capacitor
[C16.parallel.C17.parallel.resistor R17], capacitor C2, sub-circuit
CP pin CT0, sub-circuit PFT1A pin S1CT and through EMI filter
capacitor C1 to earth ground node LL0. Drain of output switch Q1 is
connected to diode D4 anode, sub-circuit PFT1A pin P1A and snubber
sub-circuit SN pin SNL2. Additional rectification efficiency and
protection is achieved by adding sub-circuit DSN (FIG. 30A) in
parallel flyback diode D4. Sub-circuit provides reduces the high
voltage stress to Q1 until flyback diode D4 begins conduction. Line
coupled, power factor corrected boost regulated output voltage of
the AC to DC converter stage (FIG. 1) appears on node PF+. The
regulated boost output PF+ connects to the following; sub-circuit
SN pin SNOUT, diode D4 cathode, capacitor
[C16.parallel.C17.parallel.R17], and snubber DSN (FIG. 30A) pin
SNOUT. Magnetic element winding node S1H of sub-circuit PFT1A is
connected to CP pin CT1A and pin PFVC of sub-circuit PFB. Magnetic
element winding node S1L of sub-circuit PFT1A is connected to CP
pin CT2A. Sub-circuit PFB using the phase of the AC line, and load
voltage generates a command pulse PFCLK. Pin PFCLK of sub-circuit
PFB (FIG. 24) is connected to the input of buffer amplifier pin GA1
of sub-circuit AMP1 (FIG. 29). Buffered high-speed gate drive
output pin GA2 of sub-circuit AMP is connected to gate of switch
FET Q1. The buffering provided by AMP shortens switch Q1 ON and OFF
times greatly reducing switch losses. The source of Q1 is connected
to current sense resistor R26, pin PFSC of sub-circuit PFB,
connected then to return node BR-. The voltage developed across R26
is feedback to PFB pin PFSC. This signal is used to protect the
switch in the event of an over current fault. Thermal switch THS1
is connected to Q1. In the event Q1 reaches approximately 105 C.
THS1 opens removing power to sub-circuit AMP, safely shutting down
the first stage. Normal operation resumes after the switch
temperature drops 20-30 C. closing THS1. Sub-circuit feedback
network FBA (FIG. 40A) pin PF1 is connected to sub-circuit PFB pin
PF1. Converter output at node PF+ (the junction of C17.parallel.C16
and D4) is connected to sub-circuit FBA pin PF+. The return line of
sub-circuit FBA pin BR- is connected to pin BR- of sub-circuit PFB.
This feed back is non-isolated; network values are selected for a
substantially constant 385-Volt output at PF+ relative to BR-. The
high-voltage haversine from the rectifier section BR pin BR+ is
connected to sub-circuit PFB pin BR+. The haversine is used with an
internal multiplier by PFB to make the converter ACDCPF appear
resistive to the AC line. Sub-circuits LL1, BR, PFB, AMP, Q1, OTP,
FBA, IFB and PFT1A perform power factor corrected AC to DC
conversion. The regulated high voltage output of this converter may
be used use to power one or more external converters connected to
the PF+ and BR- nodes. The NSME sub-circuit PPT1A provides
efficient boost action at high power levels in a very small form
factor. Sub-circuit FBA provides high-speed feedback to the
converter the speed of the boost stage provides precise output
voltage regulation and active ripple rejection. This configuration
provides power factor corrected input transient protection, rapid
line-load response, excellent regulation, and quiet efficient
operation at high temperatures.
[0099] FIG. 5 is a graph comparing typical currents in saturating
and non-saturating magnetic elements. As the inductance does not
radically change at high temperatures and currents in the NSME, the
large current spikes due to the rapid reduction of inductance
common in saturating magnetics is not seen. As a result,
destructive current levels, excessive gap leakage, magnetizing
losses, and magnetic element heating are avoided in NSME.
[0100] FIG. 6 is a schematic for non-isolated low side switch buck
converter sub-circuit NILBK. Sub-circuit NILBK consists of resistor
R20, diode D6, capacitor C6, FET transistor Q111, sub-circuit CP
(FIG. 26), sub-circuit PFT1A (FIG. 18A), sub-circuit IFB (FIG.
40B), sub-circuit AMP (FIG. 29) and sub-circuit PWFM (FIG. 33).
6 Table Element Value/part number R20 100k ohms R20 STA1206 DI Q111
IRFP460 C6 10 uf
[0101] External power source VBAT connects to pins DCIN+ and DCIN-.
From DCIN+ through resistor R20 connects to sub-circuit CP pin CP+,
sub-circuit AMP pin GA+and to sub-circuit PWFM pin PWFM+. Resistor
R20 provides startup power to the converter before regulator
sub-circuit CP reaches it full 18-volt output. VBAT negative is
connected to pin DCIN- connects to sub-circuit PWFM pin PWFM0,
sub-circuit AMP pin GA0, Q111 source, sub-circuit IFB pin FBE,
sub-circuit CP pin CT0, and sub-circuit PFT1 pin SICT. Magnetic
element winding node S1H of sub-circuit PFT1A is connected to CP
pin CT1A. Magnetic element winding node S1CT of sub-circuit PFT1 is
connected to CP pin CT0. Magnetic element winding node S1H of
sub-circuit PFT1A is connected to CP pin CT2A. The regulated 18
volts from sub-circuit CP+ is connected to R20, sub-circuit AMP pin
GA+ and to sub-circuit PWFM pin PWFM+. Sub-circuit PWFM is designed
for variable pulse width operation. PWFM is configured for maximum
pulse width 90-95% with no feedback current from sub-circuit IFB
pin FBC. Increasing the feedback current reduces the pulse-width
and output voltage from converter NILBK. Sub-circuit PWFM clock/PWM
output pin CLK is connected to the input pin GA1 of buffer
sub-circuit AMP. The output of sub-circuit AMP pin GA2 is connected
to the gate of Q111. Input node DCIN+ connects to the cathode of
flyback diode D6, sub-circuit IFB pin OUT+, resistor RLOAD,
capacitor C6 and pin B+. The drain of Q111 is connected to
sub-circuit PFT1 pin P1B and the anode of D6. Pin P1A of
sub-circuit PFT1A is connected to capacitor C6, RLOAD, sub-circuit
IFB pin OUT- and to node B- With sub-circuit PWFM pin CLK high
buffer AMP output pin GA2 charges the gate of transistor switch
Q111. Switch Q111 conducts charging capacitor C10 through NSME
PFT1A from source VBAT and storing energy in PFT1A. Feedback output
pin FBC from sub-circuit IFB is connected to sub-circuit PWFM
pulse-width adjustment pin PW1. Sub-circuit IFB removes current
from PW1 commanding PWFM to reduce the pulse-width or on time of
signal CLK. After sub-circuit PWFM reaches the commanded
pulse-width PWFM switches output pin CLK low turning "off" Q111
stopping the current into PFT1A. The energy not transferred into
regulator sub-circuit CP load is released from NSME PFT1A into the
now forward biased diode D6 charging capacitor C6. By modulating
the "on" time of switch Q111 the converter buck voltage is
regulated. Regulated voltage is developed across Nodes B- and B+.
Sub-circuit IFB provides the isolated feedback voltage to the
sub-circuit PWFM. When sub-circuit IFB senses the converter output
(nodes B+ and B-) is at the designed voltage, current from REF is
removed from PM1. Sinking current from PM1 commands the PWFM to a
shorter pulse-width thus reducing the converter output voltage. In
the event the feedback signal from IFB commands the PWFM to minimum
output. Gate drive to switch Q111 is removed stopping all buck
activity capacitor C6 discharges through RLOAD. Input current from
VBAT is sinusoidal making the converter very quiet. In addition the
switch Q111 is not exposed to large flyback voltage. Placing less
stress on the switches thereby increasing the MTBF. Sub-circuit
NILBK takes advantage of the desirable properties of the NSME in
this converter topology. Adjusting the NSME 100 (FIG. 18A) primary
inductance and component values in sub-circuit IFB determines the
output buck voltage.
[0102] FIG. 8 is a schematic for a tank coupled single stage
converter sub-circuit TCTP. Sub-circuit TCTP consists of resistor
R20 and RLOAD, capacitor C10, Darlington transistors Q10 and Q20,
sub-circuit CP (FIG. 26), sub-circuit PFT1 (FIG. 18), sub-circuit
OUTB (FIG. 25A), sub-circuit IFB (FIG. 40B) and sub-circuit PWFM
(FIG. 33).
7 Table Element Value/part number R20 5k ohms Q10 TST541 Q20
IRFP460 C10 1.8 uf
[0103] External power source VBAT connects to pins DCIN+ and DCIN-.
From DCIN+ connects to Q10 collector then through resistor R20
connects to sub-circuit CP pin CP+ and to sub-circuit PWFM pin
PWFM+. Resistor R20 provides startup power to the converter before
regulator sub-circuit CP reaches it full 18-volt output. VBAT
negative is connected to pin DCIN- ground/return node GND. Node GND
connects to sub-circuit PWFM0 pin PWFM0, Q20 collector, C10,
sub-circuit CP pin CT0 and sub-circuit PFT1 pin S1CT. Magnetic
element winding node S1H of sub-circuit PFT1 is connected to CP
CT1A. Magnetic element winding node S1L of sub-circuit PFT1 is
connected to CP CT2A. Magnetic element winding node SICT of
sub-circuit PFT1 is connected to CP pin CT0. Magnetic element
winding node S2H of sub-circuit PFT1 is connected to CP pin CT2A.
The regulated 18 volts from sub-circuit CP+ is connected to R20 and
to sub-circuit PWFM pin PWFM+. Sub-circuit PWFM is designed for a
constant 50% duty cycle variable frequency generator. Sub-circuit
PWFM clock output pin CLK is connected to the base of Q10 and Q20.
The emitters of Q10 and Q20 are connected to sub-circuit PFT1 pin
P1B. This forms an emitter follower configuration. Pin P1A of
sub-circuit PFT1 is connected through tank capacitor C10 to node
GND. With PWFM CLK pin high forward biased transistor Q10 supplies
current to the tank from BAT1 charging capacitor C10 through NSME
PFT1 and transferring energy into PFT1. Sub-circuit PWFM switches
CLK low turning "off" Q10 stopping the current into PFT1. Energy
not transferred into the load is released from NSME PFT1 into the
now forward biased PNP transistor Q20 back into capacitor C10. Thus
any energy not used by the secondary loads is transferred back to
the primary tank to be used next cycle. When the switching occurs
at the resonant frequency large circulating currents develop in the
tank. Also C10 is charged and discharged to very large voltages.
Oscillograph in FIG. 35 is the actual voltage developed across
capacitor C10 with VBAT equal to 18 volts. A very large 229-Volts
peak to peak was developed across the nodes P1A and P1A of NSME
PFT1. The large primary voltage generates large biases in the NSME
PFT1 to be flux harvested by the windings 102 and 103 (FIG. 18) and
transferred to a load or rectifier sub-circuit OUTB. Magnetic
element winding node S2L of sub-circuit PFT1 is connected to OUTB
C8b. Magnetic element winding node S2H of sub-circuit PFT1 is
connected to C7B of sub-circuit OUTB node OUT-. Node OUT- is
connected to RLOAD, pin B- and to sub-circuit IFB pin OUT-.
Rectified power is delivered to pin OUT+ of OUTB and is connected
to RLOAD, pin B+ and to sub-circuit IFB pin OUT+. Sub-circuit IFB
provides the isolated feedback signal to the sub-circuit PWFM.
Frequency control pin FM1 of sub-circuit PWFM is connected to
sub-circuit IFB pin FBE. Internal reference pin REF of sub-circuit
PWFM is connected to sub-circuit IFB pin FBC. PWFM is designed to
operate at the resonate frequency of the tank. When sub-circuit IFB
senses the converter output is at the designed voltage, current
from REF is injected into FM1. Injecting current into FM1 commands
PWFM to a lower frequency. Operating below resonance reduces the
amount of energy added to the primary tank thus reducing the
converter output voltage. In the event the feedback signal from IFB
commands the PWFM to 0 Hz all primary activity stops. Input current
from VBAT is sinusoidal making the converter very quiet. In
addition the switches Q10 and Q20 are never exposed to the large
circulating voltage (FIG. 35). Placing less stress on the switches
thereby increasing the MTBF. Sub-circuit TCTP takes advantage of
the desirable properties of the NSME in this converter topology.
Adjusting secondary turns allows TCTP to generate very large AC or
DC output voltages as well as low-voltage high current outputs.
[0104] FIG. 9 is a schematic for non-isolated low side switch boost
converter sub-circuit NILSBST. Sub-circuit NILSBST consists of
resistor R20 and RLOAD, diode D6, capacitor C6, FET transistor
Q111, sub-circuit CP (FIG. 26), sub-circuit PFT1A (FIG. 18A),
sub-circuit FBI (FIG. 41), sub-circuit AMP (FIG. 29) and
sub-circuit PWFM (FIG. 33).
8 Table Element Value/part number R20 100k ohms Q111 IRFP460 D6
STA1206 DI C6 200 uf
[0105] External power source VBAT connects to pins DCIN+ and DCIN-.
From DCIN+ Resistor R20 connects to sub-circuit CP pin CP+,
sub-circuit AMP pin GA+ and to sub-circuit PWFM pin PWFM+. Resistor
R20 provides startup power to the converter before regulator
sub-circuit CP reaches it full 18-volt output. VBAT negative is
connected to pin DCIN- and ground return node GND. Node GND
connects to sub-circuit PWFM pin PWFM0, sub-circuit AMP pin GA0,
Q111 source, sub-circuit FBA pin BR-, sub-circuit FBA pin FBA,
sub-circuit CP pin CT0, capacitor C6, resistor RLOAD, transistor
Q111 source, and sub-circuit PFT1 pin SICT. Magnetic element
winding node S1H of sub-circuit PFT1A is connected to CP pin CT1A.
Magnetic element winding node S1CT of sub-circuit PFT1 is connected
to CP pin CT0. Magnetic element winding node S2H of sub-circuit
PFT1A is connected to CP pin CT2A. The regulated 18 volts from
sub-circuit CP+ is connected to R20, sub-circuit AMP pin GA+and to
sub-circuit PWFM pin PWFM+. Sub-circuit PWFM is designed for
variable pulse width operation. PWFM is configured for maximum
pulse width 90-95% (maximum boost voltage) with no feedback current
from sub-circuit FBI. Increasing the feedback current reduces the
pulse-width reducing the boost voltage and reducing the output from
converter NILSBST. Sub-circuit PWFM clock/PWM output pin CLK is
connected to the input pin GA1 of buffer sub-circuit AMP. The
output of sub-circuit AMP pin GA2 is connected to the gate of Q111.
Input node DCIN+ connects to the NSME PFT1A pin P1A. The drain of
Q11 is connected to sub-circuit PFT1A pin P1B and the anode of D6.
Cathode of diode D6 is connected to sub-circuit FBA pin PF+,
resistor RLOAD, C6 and pin BK+. With sub-circuit PWFM pin CLK high
buffer AMP output pin GA2 charges the gate of transistor switch
Q111. Switch Q111 conducts reverse biasing diode D6 capacitor C10
stops charging through NSME PFT1A from source VBAT. During the time
Q111 is conducting, energy is stored in NSME sub-circuit PFT1A.
Feedback output pin FBC from sub-circuit FBI is connected to
sub-circuit PWFM pulse-width adjustment pin PW1. Sub-circuit FBI
removes current from PW1 commanding PWFM to reduce the pulse-width
or on time of signal CLK. After sub-circuit PWFM reaches the
commanded pulse-width PFFM switches CLK low turning "off" Q111
stopping the current into PFT1A. The energy not transferred into
regulator sub-circuit CP load is released from NSME PFT1A into the
now forward biased diode D6 charging capacitor C6. By modulating
the "on" time of switch Q111 the converter boost voltage is
regulated. Regulated voltage is developed across Nodes B- and B+.
Sub-circuit IFB provides the feedback current to the sub-circuit
PWFM. When sub-circuit IFB senses the converter output (nodes B+
and B-) is at or greater than the designed voltage, current is
removed from PM1. Sinking current from PM1 commands the PWFM to a
shorter pulse-width thus reducing the converter output voltage. In
the event the feedback signal from IFB commands the PWFM to minimum
output. Gate drive to switch Q111 is removed stopping all boost
activity capacitor C6 charges to VBAT. Input current from VBAT is
sinusoidal making the converter very quiet. In addition the switch
Q111 is not exposed to large flyback voltage. Placing less stress
on the switches thereby increasing the MTBF. Sub-circuit NILBK
takes advantage of the desirable properties of the NSME in this
converter topology. Adjusting the NSME 100 (FIG. 18A) primary
inductance and component values in sub-circuit IFB determines the
output boost voltage.
[0106] FIG. 10 is a schematic for a two stage isolated DC to DC
boost controlled push-pull converter BSTPP. Sub-circuit BSTPP
consists of diode D14, capacitor C14, FET transistor Q14,
sub-circuit REG (FIG. 36), sub-circuit BL1, (FIG. 18B), sub-circuit
IFB (FIG. 40B), sub-circuit AMP (FIG. 29), sub-circuit DCAC1, and
sub-circuit PWFM (FIG. 33). External power source VBAT connects to
pins DCIN+ and DCIN-.
9 Table Element Value/part number Q31 IRFP460 D14 STA1206 DI C14 10
uf
[0107] From pin DCIN+ connects to sub-circuit REG pin RIN+ and
sub-circuit BL1, pin P1A. Voltage regulator sub-circuit output pin
+18V connects to sub-circuit AMP pin GA+ and to sub-circuit PWFM
pin PWFM+. Sub-circuit REG provides regulated low voltage power to
the controller and to the main switch buffers. VBAT negative is
connected to pin DCIN- and ground return node GND. Node GND
connects to sub-circuit PWFM pin PWFM0, sub-circuit AMP pin GA0,
Q14 source, capacitor C14, sub-circuit IFB pin FBE, sub-circuit REG
pin REG0, sub-circuit DCAC1 pin DC-. Sub-circuit PWFM (FIG. 33) is
designed for variable pulse width operation. The nominal frequency
is between 20-600 Khz PWFM is configured for maximum pulse width
90% (maximum boost voltage) with no feedback current from
sub-circuit FBI. Increasing the feedback current reduces the
pulse-width reducing the boost voltage and reducing the output from
converter BSTPP. Sub-circuit PWFM clock/PWM output pin CLK is
connected to the input pin GA1 of buffer sub-circuit AMP (FIG. 29).
The output of switch speed up buffer sub-circuit AMP pin GA2 is
connected to the gate of Q14. Input node DCIN+ connects to the NSME
BL1, pin P1A. The drain of Q14 is connected to sub-circuit BL1, pin
P1B and the anode of D14. Cathode of flyback diode D14 is connected
to sub-circuit DCAC1 pin DC+ and C14. With sub-circuit PWFM pin CLK
high buffer AMP output pin GA2 charges the gate of transistor
switch Q14. Switch Q14 conducts reverse biasing diode D14 capacitor
C14 stops charging through NSME BL1, from source VBAT. During the
time Q14 is conducting, energy is stored in NSME sub-circuit BL1.
Feedback output pin FBC from sub-circuit IFB is connected to
sub-circuit PWFM pulse-width adjustment pin PW1. Sub-circuit IFB
removes current from PW1 commanding PWFM to reduce the pulse-width
or "on" time of signal CLK. After sub-circuit PWFM reaches the
commanded pulse-width PFFM switches CLK low turning "off" Q14
stopping the current into BL1. The energy is released from NSME BL1
into the now forward biased flyback diode D14 charging capacitor
C14. By modulating the "on" time of switch Q14 the converter boost
voltage is regulated. Regulated voltage is developed across C14
Nodes DC+ and GND is provided to the isolated constant frequency
push-pull DC to AC converter sub-circuit DCAC1 (FIG. 2).
Sub-circuit DCAC1 provides efficient conversion of the regulated
boost voltage to a higher or lower voltage set by the magnetic
element-winding ratio The center tap of the push-pull output
magnetic is connected to, sub-circuit OUTB pin OUT-, RLOAD,
sub-circuit IFB pin OUT- and the pin OUT- forming the return line
for the load and feedback network. Output of sub-circuit DCAC1 pin
ACH is connected to sub-circuit OUTB pin C7b. Output of sub-circuit
DCAC1 pin ACL is connected to sub-circuit OUTB pin C8b. Sub-circuit
OUTB provides rectification of the AC power generated by
sub-circuit DCAC1. Since the non-saturating magnetic converter has
low output ripple, minimal filtering is required by OUTB. This
further reduces cost and improves efficiency as losses to filter
components are minimized. Sub-circuit IFB provides the isolated
feedback current to the sub-circuit PWFM. When sub-circuit IFB
senses the converter output (nodes OUT+ and OUT-) is greater than
the designed/desired voltage, current is removed from node PM1.
Sinking current from PM1 commands the PWFM to a shorter pulse-width
thus reducing the converter output voltage. In the event the
feedback signal from IFB commands the PWFM to minimum output. Gate
drive to switch Q14 is removed stopping all boost activity
capacitor C14 charges to VBAT. As the non-saturating does not
saturate the destructive noisy current "spikes" common to prior art
are absent. Input current from VBAT to charge C14 is sinusoidal
making the converter very quiet. In addition the switch Q14 is not
exposed a potentially destructive current spike. Placing less
stress on the switches thereby increasing the MTBF. Sub-circuit
BSTPP takes advantage of the desirable properties of the NSME.
Adjusting the NSME BL1, (FIG. 18B) sets the amount of boost voltage
available to the final push-pull isolation stage. Greater
efficiencies are achieved at higher voltages. The final output
voltage is set by the feedback set point and the turns ratio of the
push-pull element PPT1 (FIG. 19).
[0108] FIG. 11 is a graph of permeability as a function of
temperature for typical prior art magnetic element material. The
high permeability material in FIG. 11 exhibits large changes in
permeability of almost 100% over a 100 C. range as compared to the
less than 5% change for the material in FIG. 17. The increase in
permeability at high temperatures of the prior art material
increases the flux density resulting in core saturation for a
constant power level. (See FIG. 12) Thus the prior art core must be
derated at least 100% to operate over extended temperatures. The
instant invention takes advantage of the desirable properties of
the NSME. Eliminating the need to derate the magnetic element. As
the magnetic element performs better at high temperatures,
currently limited by melting wire insulation.
[0109] FIG. 12 is a graph of flux density as a function of
temperature for typical prior art magnetic element material. The
reduction of maximum flux density with temperature is typical of
the saturating magnetic element prior art material. Thus the prior
art core is commonly derated at least 100% to operate over extended
temperatures. Resulting in a larger more expensive design, and or
the requirement to cool the core.
[0110] FIG. 12A is a graph of magnetic element losses for various
flux densities and operating frequencies typical of prior art
magnetic element material.
[0111] FIG. 13 is a graph showing standard switching losses. The
hashed area represents the time when the switch is in a resistive
state. The hashed area is proportional to the amount of energy lost
each time the output switch operates. Total power lost is the
product of the loss per switch times the switching frequency.
[0112] FIG. 14 is a graph showing the inventions switching losses.
The hashed area represents the time when the switch is in a
resistive state. The smaller hashed area is due to the action of
the buffer in FIG. 29 and the snubber isolation diode D805 in FIG.
30. Generally the NSME has a wider usable frequency band and can be
magnetized from higher primary voltages. Higher operating voltages
have proportionally smaller currents for a given power level thus
proportionally lower losses. Switching losses more closely resemble
I.sup.2R losses. Most switching loss occurs during turn "on" and
turn "off" transitions; total switching losses are reduced
proportionally by the lower switching frequencies and faster
transition times characteristic of the disclosed NSME converters.
In addition the properties of the NSME allow operation at
temperature extremes beyond the tolerance of standard prior art
magnetics and their geometry's. The combined contributions of the
above yields a converter that requires little or no forced
air-cooling. (See FIG. 15, 16, and 17)
[0113] FIG. 15 is a graph of the NSME magnetization curves for Kool
Mu material. The invention makes advantageous use of the available
saturation range of the NSME.
[0114] FIG. 16 is a graph of the Kool Mu NSME losses for various
flux densities and operating frequencies. It can be seen from the
data that much higher flux densities are available per unit losses
over the prior art.
[0115] FIG. 17 is a plot of permeability vs. temperature for
several Kool Mu materials. This data demonstrates the usefulness
and stability of the magnetic properties over temperature.
[0116] FIG. 18 is a schematic representation of the non-saturating
magnetic boost element PFT1. Sub-circuit PFT1 consists of a primary
winding 100 around a NSME 101 with two center-tapped windings 102
and 103.
10 Table Element Value/part number 100 55 turns 203 uh 101 2
.times. 77932-A7 102 14 turns 102 14 turns
[0117] The primary winding 100 has nodes P1B and P1A for
connections to external AC source. Secondary 102 winding has
center-tapped node S1CT and node S1H and S1L connections to the
upper and lower halves respectively. Secondary 103 winding has
center-tapped node S2CT and node S2H and S2L connections to the
upper and lower halves respectively. Both 102 and 103 are connected
to external full-wave rectifier assemblies. Magnetic element
magnetic element 101 comprises a non-saturating, low permeability
magnetic material. The permeability is on the order of 26 u with a
range of 1 u to 550 u, as compared to the prior art, which ranges
from 1500 to 5000 u. Flyback management is of concern when using
NSME in a boost converter because the magnetic element generates
high drain source voltages across the primary switch during the
reverse recovery time of the flyback (output) diode. The magnitude
per cycle of flyback current from NSME is greater for a given input
magnetizing force relative to the prior art. (See FIG. 5) For
example, Kool Mu torroids (Materials from Magnetics) are suitable
for this application. This material is not identified by way of
limitation. The material comprises, by weight, 85% iron, 6%
aluminum, and 9% silicon. Further, the magnetic element may be air,
(permeablity=1); a molypermalloy powder, (MPP) a high flux MPP, a
powder, a gapped ferrite, a tape wound, a cut magnetic element, a
laminated, or an amorphous magnetic element. Unlike the prior art,
the NSME is temperature tolerant in that the critical parameters of
permeability and saturability remain substantially unaffected
during extreme thermal operation over time. Some materials such as
air also exhibit little or no change in permeability or saturation
levels over time, temperature, and conditions. The prior art uses
high permeability saturable materials often greater than 2000 u
permeability. These magnetics exhibit undesirable changes in
permeability and saturation during operation at or near rated
output making operation at high power levels and temperature
difficult. See the permeability vs. temperature FIG. 11. This
deficiency is overcome by the use of expensive oversized magnetic
elements or output current sharing with multiple supplies. (See the
graph b.sub.sat vs. temperature FIG. 12) This invention takes
advantage of the desirable properties of NSME. See the permeability
vs. temperature FIG. 17. Prior art saturating magnetic element
commonly is operating at frequencies greater than 500 KHz to
achieve greater power levels. As a result practitioners experience
exponentially greater core losses (see FIG. 12A) at high
frequencies. NSME support operation at lower frequencies 20-600 KHz
further reducing switching losses and magnetic element losses
allowing operation at even higher temperatures. See the loss
density vs. flux density FIG. 16. Unlike the prior art, the instant
invention uses voltage mode control with over-current shutdown.
Material selection is also based upon mass and efficiency. By
increasing the mass of the magnetic element, more energy is coupled
more efficiently. Since there are reduced losses, the dissipation
profile follows I2R/copper losses. The magnetic element is operated
at duty cycles of 0%+ to 90%, which, when used to control the
primary side push-pull voltage, results in efficiencies on the
order of 90%.
[0118] FIG. 18A is a schematic representation of the NSME PFT1A
Sub-circuit transformer PFT1A consists of a primary winding 100
around a NSME 101 with a center-tapped winding 102.
11TABLE FIG. 18A Element Value/part number 100 55 turns 230 uh 101
2 .times. 77932-A7 102 14 turns
[0119] The primary winding 100 has nodes P1B and P1A for
connections to external AC source. Secondary 102 winding has
center-tapped node S1CT and node S1H and S1L connections to the
upper and lower halves respectively. Winding 102 are typically
connected to external full-wave rectifier assemblies. Magnetic
element 101 comprises a non-saturating, low permeability magnetic
material. The permeability is on the order of 26 u with a range of
1 u to 550 u, as compared to the prior art, which is on the order
of 2500 u.
[0120] Flyback management is of concern when using such a magnetic
element because the magnetic element generates high drain source
voltages across the primary switch during the reverse recovery time
of the flyback diode. Flyback current is available for longer
periods after the primary switch opens. (See FIG. 5) For example,
Kool Mu (Materials from Magnetics are suitable for this
application. This material is not identified by way of limitation.
The material comprises, by weight: 85% iron, 6% aluminum, and 9%
silicon. Further, the magnetic element may be air; (air magnetic
element permeablity=1); a molypermalloy powder (MPP) magnetic
element; a high flux MPP magnetic element; a powder magnetic
element; a gapped ferrite magnetic element; a tape wound magnetic
element; a cut magnetic element; a laminated magnetic element; or
an amorphous magnetic element. During operation the temperature of
the NSME rises, the permeability slowly decreases, thereby
increasing the saturation point. Some materials such as air exhibit
no or very small changes in permeability or saturation levels.
Unlike prior art using high permeability materials greater than
2000 u permeability rapidly increases at high temperatures. See the
permeability vs. temperature FIG. 11. Prior art also suffers from
reduced magnetic element saturation levels at high temperatures,
making operation at high power levels and temperature difficult and
may require the use of expensive oversized magnetic elements. See
the graph b.sub.sat vs. temperature FIG. 12 this invention takes
advantage of the desirable NSME properties. See the permeability
vs. temperature FIG. 17. Operation at lower frequencies 20-600 KHz
reduces switching losses and magnetic element losses allowing
operation at higher temperatures. See the loss density vs. flux
density FIG. 16. Unlike the prior art, the instant invention uses
voltage mode control with over-current shutdown. Material selection
is also based upon mass and efficiency. By increasing the mass of
the magnetic element, more energy is coupled more efficiently.
Since there are reduced losses, the dissipation profile follows
I2R/copper losses. The magnetic element is operated at duty cycles
of 0%+ to 90%, which, when used to control the primary side
push-pull voltage, results in efficiencies on the order of 90%.
FIG. 18B is a schematic representation of the NSME BL1, Sub-circuit
BL1, consists of a winding 100 around a NSME 101.
12TABLE FIG. 18 Element Value/part number 107 40 turns 50 uh 101 2
.times. 77932-A7
[0121] Magnetic element BL1, may also be constructed from one or
more magnetic elements in series or parallel. Assuming minimal
mutual coupling the total inductance is the arithmetic sum of the
individual inductances. For elements in parallel the (assuming
minimal mutual coupling) the total inductance is the reciprocal of
the arithmetical sum of the reciprocal of the individual
inductances. In this way multiple magnetic elements may be arranged
to meet packaging, manufacturing, and power requirements. The
primary winding 100 has nodes P2B and P2A for connections to
external AC source. Magnetic element 101 comprises a
non-saturating, low permeability magnetic material. The
permeability is on the order of 26 u with a range of 1 u to 550 u,
as compared to the prior art, which is on the order of 2500 to 5000
u. Flyback management is of concern when using such a magnetic
element because the magnetic element generates high drain source
voltages across the primary switch during the reverse recovery time
of the flyback diode. Flyback current is available for longer
periods after the primary switch opens. (See FIG. 5) For example,
Kool Mu (Materials from Magnetics are suitable for this
application. This material is not identified by way of limitation.
The material comprises, by weight: 85% iron, 6% aluminum, and 9%
silicon. Further, the magnetic element may be air (air magnetic
element permeablity=1); a molypermalloy powder (MPP) magnetic
element; a high flux MPP magnetic element; a powder magnetic
element; a gapped ferrite magnetic element; a tape wound magnetic
element; a cut magnetic element; a laminated magnetic element; or
an amorphous magnetic element. During operation temperature of the
magnetic element rises, the permeability slowly decreases, thereby
increasing the saturation point. Some materials such as air exhibit
no or very small changes in permeability or saturation levels.
Unlike prior art using high permeability materials greater than
2000 u permeability rapidly increases at high temperatures. See the
permeability vs. temperature FIG. 11. Prior art also suffers from
reduced magnetic element saturation levels at high temperatures,
making operation at high power levels and temperature difficult and
may require the use of expensive oversized magnetic elements. (See
the graph b.sub.sat vs. temperature FIG. 12) This invention takes
advantage of the desirable NSME properties. (See the permeability
vs. temperature FIG. 17.) Prior art often operates at high
switching frequencies 100-1000 kHz to avoid the saturation problem.
Only to increase switching and core losses. (See FIG. 12A) This
inventions use of the desirable NSME properties allows operation at
lower frequencies 20-600 KHz further reducing switching losses and
magnetic element. See the loss density vs. flux density FIG. 16.
Unlike the prior art, the instant invention uses voltage mode
control with over-current shutdown. Material selection is also
based upon mass and efficiency. By increasing the mass of the
magnetic element, more energy is coupled more efficiently. Since
there are reduced losses, the dissipation profile follows
I2R/copper losses.
[0122] FIG. 18C is a schematic representation of a distributed NSME
PFT1D. This is shown to exemplify distributed magnetics enable
advantageous high voltage converter design variations that support
form factor flexibility and multiple parallel secondary outputs
from series coupled voltage divided primary windings across
multiple NSME. This magnetic strategy is useful in addressing wire
insulation, form factor and packaging limitations, circuit
complexity and manufacturability. In this example a 500W converter
is required to fit in a low profile package. Sub-circuit PFTD1
consists of three magnetic elements 120, 121 and 124 with series
connected primaries.
13TABLE FIG. 18C Element Value/part number 113 77352-A7 122 23
Turns 123 23 Turns 112 67 uh (55 turns) 114 77352-A7 116 67 uh (55
turns) 117 77352-A7 118 67 uh (55 turns)
[0123] AC voltage is applied to 112 pin P1B then from P1C through
conductor 115 to 116 pin P1D. Winding 116 pin P1E is connected
through conductor 119 to 118 pins P1F then to pin P1A. Original
Sub-circuit PFT1 (FIG. 18) consists of a primary winding 100 around
a NSME 101 with two center-tapped windings 122 and 123. By way of
example sub-circuit PFT1D will be implemented as three magnetic
elements. For a 500-watt expression a total inductance of 203 uH is
required in winding 100 (FIG. 18). Dividing the primary inductance
by the number of elements, in this case three requires elements
112, 116 and 118 have 67 uH of inductance. The energy storage is
equally distributed over the magnetic assembly 120, 121 and 124.
The 500 watt converter in (FIG. 1) employs two (Kool Mu part number
77932-A7) 0.9 oz (25 gram) NSME to form 101 (FIG. 18). Sub-circuit
PFT1 magnetic element 101 (FIG. 18) may be expressed as three
0.5-0.7 oz (14-19 gram) elements. Three 0.5-oz Kool Mu elements
(part number 77352-A7) were selected. To realize 67 uH of primary
inductance 55 turns are required for elements 112, 116 and 118. The
primary circuit has nodes P1B and P1A for connections to external
AC source. Secondary 102 winding has center-tapped node S1CT and
node S1H and S1L connections to the upper and lower halves
respectively. Secondary 123 winding has center-tapped node S2CT and
node S2H and S2L connections to the upper and lower halves
respectively. Both 122 and 123 are connected to external full-wave
rectifier assemblies. Magnetic element magnetic element 120, 121
and 124 comprises a non-saturating, low permeability magnetic
material. The permeability is on the order of 26 u with a range of
1 u to 550 u, as compared to the prior art, which is on the order
of 2500 u. Flyback management is of concern when using such a
magnetic element because the magnetic element generates high drain
source voltages across the primary switch during the reverse
recovery time of the flyback diode. Flyback current is available
for longer periods after the primary switch opens. (See FIG. 5) For
example, Kool Mu (Materials from Magnetics are suitable for this
application. This material is not identified by way of limitation.
The material comprises, by weight: 85% iron, 6% aluminum, and 9%
silicon. Further, the magnetic element may be air (air magnetic
element permeablity=1); a molypermalloy powder (MPP) magnetic
element; a high flux MPP magnetic element; a powder magnetic
element; a gapped ferrite magnetic element; a tape wound magnetic
element; a cut magnetic element; a laminated magnetic element; or
an amorphous magnetic element. During operation the temperature of
the NSME, the permeability slowly decreases, thereby increasing the
saturation point. Some materials such as air exhibit no or very
small changes in permeability or saturation levels. Unlike prior
art using high permeability materials greater than 2000 u
permeability rapidly increases at high temperatures. See the
permeability vs. temperature FIG. 11. Prior art also suffers from
reduced magnetic element saturation levels at high temperatures,
making operation at high power levels and temperature difficult and
may require the use of expensive oversized magnetic elements. (See
the graph b t vs. temperature FIG. 12) This invention takes
advantage of the desirable NSME properties. See the permeability
vs. temperature FIG. 17. Prior art saturating magnetic element
commonly is operating at frequencies greater than 500 KHz to
achieve greater power levels. As a result practitioners experience
exponentially greater core losses (see FIG. 12A) at high
frequencies. NSME allows operation at lower frequencies 20-600 KHz
further reduces switching losses and magnetic element losses
allowing operation at even higher temperatures. (See the loss
density vs. flux density FIG. 16) Unlike the prior art, the instant
invention uses voltage mode control with over-current shutdown.
Material selection is also based upon mass and efficiency. By
increasing the mass of the magnetic element, more energy is coupled
more efficiently. Since there are reduced losses, the dissipation
profile follows I2R/copper losses. The magnetic element is operated
at duty cycles of 0%+to 90%, which, when used to control the
primary side push-pull voltage, results in efficiencies on the
order of 90%.
[0124] FIG. 19 is a schematic representation of the non-saturating
push-pull magnetic element sub-circuit PPT1
[0125] Sub-circuit PPT1 consists of a center-tapped primary winding
104 around a NSME 106 with one secondary center-tapped winding
105.
14TABLE FIG. 19 Element Value/part number 106 77259-A7 105 10 Turns
104 70 Turns
[0126] The primary winding 104 has nodes P2H and P2L for
connections to external AC sources, and common center-tap node
P2CT. Secondary 105 winding has center-tapped node SCT and nodes SH
and SL connections to the upper and lower halves respectively. The
invention is not limited to a single output. More secondary
windings may be added for additional outputs. Secondary 105 is
connected to an external full-wave rectifier assembly (Example FIG.
25 or 26). The magnetic element magnetic element 106 comprises a
non-saturating, low permeability magnetic material. The
permeability is on the order of 26 u with a range of 1 u to 550 u,
as compared to the prior art, which is on the order of 2500 u.
Flyback management is of concern when using such a magnetic element
as high drain source voltages across the primary switch are
generated during the reverse recovery of the flyback diode. The
falling flyback current is available for a longer period. (See FIG.
5) For example, Kool Mu (magnetic elements from Magnetics are
suitable for this application. This material is not identified by
way of limitation. The material comprises, by weight; 85% iron, 6%
aluminum, and 9% silicon. Further, the magnetic element may be air
(comprise an air magnetic element); a molypermalloy powder (MPP)
magnetic element; a high flux MPP magnetic element; a powder
magnetic element; a gapped ferrite magnetic element; a tape wound
magnetic element; a cut magnetic element; a laminated magnetic
element; or an amorphous magnetic element. During operation the
temperature of the NSME rises, the permeability slowly decreases,
thereby increasing the saturation point. Unlike prior art using
high permeability materials greater than 2000 u permeability
rapidly increases at high temperatures. See the permeability vs.
temperature FIG. 11. Prior art also suffers from reduced magnetic
element saturation levels at high temperatures, making operation at
high power levels and temperature difficult and may require the use
of expensive oversized magnetic elements. (See the bsat vs.
temperature FIG. 12) This invention takes advantage of the
desirable NSME properties. (See the permeability vs. temperature
FIG. 17) Operation at lower frequencies 20-600 KHz reduces
switching losses and magnetic element losses allowing operation at
higher temperatures. See the loss density vs. flux density FIG. 16.
Unlike the prior art, the instant invention uses voltage mode
control with over-current shutdown. Material selection is also
based upon mass and efficiency. By increasing the mass of the
magnetic element, more energy is coupled more efficiently. Since
there are reduced losses, the dissipation profile follows
I2R/copper losses. The magnetic element primary is driven in a
push-pull fashion at a duty cycle of 48-49% resulting in efficient
use of the magnetic element volume.
[0127] FIG. 19A is a schematic representation of the non-saturating
push-pull magnetic element sub-circuit PPT1. Sub-circuit PPT1
consists of a center-tapped primary winding 134 around a NSME 136
with one secondary center-tapped winding 135.
15TABLE FIG. 19A Element Value/part number 136 77259-A7 135 10
Turns 134 70 Turns
[0128] The primary winding 134 has nodes P2H and P2L for
connections to external AC sources, and common center-tap node
P2CT. Secondary 135 winding has center-tapped node SCT and nodes SH
and SL connections to the upper and lower halves respectively. The
invention is not limited to a single output winding. More secondary
windings may be added for additional outputs. Secondary 135 is
connected to an external full-wave rectifier assembly such as OUTA
(FIG. 25), OUTB (FIG. 25A) and OUTBB (FIG. 25B). The magnetic
element 136 comprises a non-saturating, low permeability magnetic
material. The permeability is on the order of 26 u with a range of
1 u to 550 u, as compared to the prior art, which is on the order
of 2500 u. Flyback management is of concern when using such a
magnetic element as high drain source voltages across the primary
switch are generated during the reverse recovery of the flyback
diode. The falling flyback current is available for a longer
period. (See FIG. 5) For example, Kool Mu (magnetic elements from
Magnetics are suitable for this application. This material is not
identified by way of limitation. The material comprises, by weight;
85% iron, 6% aluminum, and 9% silicon. Further, the magnetic
element may be air (comprise an air magnetic element); a
molypermalloy powder (MPP) magnetic element; a high flux MPP
magnetic element; a powder magnetic element; a gapped ferrite
magnetic element; a tape wound magnetic element; a cut magnetic
element; a laminated magnetic element; or an amorphous magnetic
element. During operation the temperature of the NSME rises, the
permeability slowly decreases, thereby increasing the saturation
point. Unlike prior art using high permeability materials greater
than 2000 u permeability rapidly increases at high temperatures.
See the permeability vs. temperature FIG. 11. Prior art also
suffers from reduced magnetic element saturation levels at high
temperatures, making operation at high power levels and temperature
difficult and may require the use of expensive oversized magnetic
elements. (See the bsat vs. temperature FIG. 12) This invention
takes advantage of the desirable NSME properties. (See the
permeability vs. temperature FIG. 17) Operation at lower
frequencies 20-600 KHz reduces switching losses and magnetic
element losses allowing operation at higher temperatures. See the
loss density vs. flux density FIG. 16. Unlike the prior art, the
instant invention uses voltage mode control with over-current
shutdown. Material selection is also based upon mass and
efficiency. By increasing the mass of the magnetic element, more
energy is coupled more efficiently. Since there are reduced losses,
the dissipation profile follows I2R/copper losses. The magnetic
element primary is driven in a push-pull fashion at a duty cycle of
48-49% resulting in efficient use of the magnetic element
volume.
[0129] FIG. 20 lightning input protection and filter sub-circuit
LL
[0130] FIG. 20 is a schematic showing the inventions filter and
lightning input protection circuit for an AC line connected
converter. The protection sub-circuit LL comprises a Spark gap A1,
diodes D20 and D21, capacitor C1 and magnetic elements L1 and
L2.
16TABLE FIG. 20 Element Value/part number L1 375 uH L2 375 uH C61
0.01 uF C60 0.01 uF A1 400 V Spark Gap C1 0.1 uF D20 1000 V/25A D21
1000 V/25A D22 1000 V/25A D23 1000 V/25A C2 1.8 uf
[0131] The AC line is connected to node LL2. The common input
frequencies of DC to 440Hz may be extended beyond this range with
component selection. Node LL2 is connected to NSME L1 then to node
LL5, the spark gap A1, anode of diode D22 and the cathode of diode
D20. Filter capacitor C60 is connected between node LL0 and LL6.
Filter capacitor C61 is connected between node LL0 and LL5. The low
side of AC line is connected to node LL1 then to magnetic element
L2 the other side L2 is connected to spark gap Al, anode of diode
D23 and the cathode of diode D21 and to node LL6. Capacitor C1 is
connected to earth ground C1 attenuates noise generated by the
converter. The use of non-saturating magnetic allows the input
magnetic elements to absorb very large voltages and currents
commonly generated by lightning, often without causing spark gap A1
to clamp. During UL testing sixty 16ms 2000V pulses were applied
between LL1 and LL2 without realizing spark gap A1 was missing with
out damage. During normal operation the NSME L1 flux density is a
few hundred gauss. The 75 u material from the graph of Flux Density
v. Magnetizing Force (FIG. 15) will accept flux densities at least
50 times greater with out limitation. This is an example of the
magnetic elements ability to perform well at flux densities many
times greater than prior art. Elements L1 and L2 will block
differential or common mode line transients. In the event of a very
large or long duration line to neutral transient, spark gap A1 will
clamp the voltage to a safe level of about 400V. The NSME L1 and L2
have the added benefit of reducing conducted noise generated by the
converter.
[0132] FIG. 21 alternate lightning input protection sub-circuit
LLA
[0133] FIG. 21 is a schematic showing the inventions alternate
lightning protection sub-circuit for an AC line connected
converter. The protection circuit comprises a fuse F1, Spark gap
A1, capacitors C1, C60 and C61 and NSME L3.
17TABLE FIG. 21 Element Value/part number L3 750 uH C61 0.01 uF C60
0.01 uF F1 10A A1 400 V Spark Gap C1 0.1 uF D20 1000 V/25A D21 1000
V/25A D22 1000 V/25A D23 1000 V/25A C2 1.8 uf
[0134] High side of AC line is connected to node LL2, fuse F1 the
load side of the fuse is connected to NSME L3 and to capacitor C61.
The load side L3 is connected to spark gap A1 and the cathode of
diode D20 and anode of D22 forming node LL5. The low side of AC
line is connected to node LL6, capacitor C60, spark gap A1, and the
cathode of diode D21 and anode of D23. The anodes of diodes D20 and
D21 are connected to Capacitor C1. Capacitor C1 is connected to
earth ground. C1 attenuates radiated noise or EMI generated by the
converter. The cathode of diodes D22 and D23 are connected to
Capacitor C2. Capacitor C2 decouples high frequency harmonic
currents from the line. Capacitors C1, C61 and C60 are connected to
earth ground node LL0. The use of non-saturating magnetics allows
the input magnetic element to absorb very large voltages and
currents commonly generated on the AC line by lightning. A
transient on the AC line will be limited by capacitors C60 and C61
and blocked by the non-saturating magnetic L3. In the event of a
very large or long duration line to neutral transient, magnetic
element L3 will allow the voltage to rise across spark gap A1, the
spark gap will clamp the voltage to a safe level protecting the
rectifier diodes D20-D23. The NSME L3 has the added benefit of
reducing conducted noise generated by the converter. C1 connected
to the ground plane is effective in attenuating conducted and
radiated EMI.
[0135] FIG. 22 AC line rectifier sub-circuit BR
[0136] FIG. 22 is a schematic showing the inventions AC line
rectifier. The rectifier sub-circuit BR1 comprises diodes D20, D21,
D22 and D23 and capacitor C2.
18TABLE FIG. 22 Element Value/part number D20 1000 V/25A D21 1000
V/25A D22 1000 V/25A D23 1000 V/25A C2 1.8 uf
[0137] An AC or DC signal from the input filter is connected to
bridge rectifier to nodes BR1 and BR2. Node BR1 connects diode D22
anode to D20 cathode. Node BR2 connects diode D23 anode to D21
cathode. Node BR+ connects diode D22 cathode to D23 cathode. Node
BR- connects diode D20 anode to D21 anode. The common input
frequencies of DC to 440 Hz may be extended beyond this range with
component selection. Capacitor C2 is selected to improve power
factor for a particular operating frequency and to de-couple
switching currents from the line. Diodes are selected to reliably
block the expected line voltage and current demands of the next
converter stage.
[0138] FIG. 23 controller sub-circuit PFA
[0139] FIG. 23 is the inventions AC to DC controller sub-circuit.
Sub-circuit PFA consists of resistors R313 and R316, capacitors
C308, and C313 and PWM controller IC U1A.
19TABLE FIG. 23 Element Value/part number C311 0.1 uf C308 .01 uf
R313 15k ohms R316 15k ohms C313 4700 pf R308 25k ohms U1A MIC38C43
(Micrel)
[0140] Control element U1A connects to a circuit with the following
series connections: from pin 1 to feedback node/pin PF1 then to
capacitor C308 then to the pin 2 node of U1A. Internal 5.1-volt
reference U1A pin 8 or node PFA2 through resistor R308 to the pin 4
node. U1A pin 4 is connected through capacitor C313 to return node
BR-. This arrangement allows the PFC output to be pulse width
modulated with application of voltage to PF1. External feedback
current applied to U1A pin 1 and node PF1. Node PFVC is connected
to resistor R313 to pin 3 of U1A. Resistor R316 is connected to pin
3 then to return node BR-. Power pin 7 is connected to node PFA+.
Control element switch drive U1A pin 6 is connected to node PFCLK.
Return ground node of U1A pin 5 is connected to return node BR-. In
the event of a component failure in the primary feed networks such
as IPFFB (FIG. 40), FBA (FIG. 40A), IFB (FIG. 40B) and FB1 (FIG.
41). The output voltage of the boost stage may rapidly increase to
destructive levels. Fast over voltage feedback networks IOVFB (FIG.
40C) or OVP2 (FIG. 42B) increases the current into PF1 thereby
limiting the output voltage to a safe level. In addition latching
type over voltage protection networks such as OVP (FIG. 42), OVP1
(FIG. 42A) and OVP2 (FIG. 42B) maybe used. The latching type kills
power to the control circuit thereby stopping the boost action. The
latching type networks require power to be cycled to the converter
to reset the latch. IFB Input node PFVC is connected to resistor
R313 to internal zero crossing detector connected to pin 3 and
through R316 to return node BR-. PFVC is connected to a magnetic
element winding referenced to BR-. A new conduction cycle is
started each time the bias in the magnetic element goes to zero.
Power factor corrected is realized by chopping the input at a high
frequency. The average pulse width decreases at higher line voltage
and increases at lower voltage for a given load. Frequency is lower
at line peaks and higher around zero crossings. In this way the
converter operates with a high input power factor.
[0141] FIG. 24 Controller with power factor corrected sub-circuit
PFB FIG. 24 is the alternate power factor controller sub-circuit.
Sub-circuit PFB consists of resistors R313, R339, R314, R315, R328,
R340, R341 and R346, diode D308, capacitors C310, C318, C338, C340,
C341 and C342, transistor Q305, and control element IC U1B.
20TABLE FIG. 24 Element Value/part number Q305 BCX70KCT R339 432k
ohms C338 0.22 uf C318 0.22 uf R314 2.2 MEG ohms R315 715k ohms
C341 0.33 uf C342 0.01 uf C340 0.001 uf R328 1 MEG ohms R346 7.15k
ohms D308 10BQ040 R340 449k ohms R313 22k ohms U1B MC34262
(Motorola) R341 499k ohms
[0142] Control element U1B connects to a circuit with the following
series connections: from pin 1 to node/pin PF1 to capacitor C338 in
series with resistor R339, and then to the pin 2 node of U1B. Pin 1
is the input to an internal error amplifier and connection to
external feedback networks. (See FIG. 40, 40A, 40B, 40C. and 41)
Increasing the voltage on pin 1 decreases the pulse width of the
PFCLK node pin 7. Resistor R328 is connected to the fullwave
rectified AC line haversine voltage on node BR+ then to U1B pin 3
and then to resistor R346 in parallel with capacitor C342 to return
node BR-. Node PFSC connects to series resistors [R341+R340] which
are connected to U1B pin 4 then to diode D308 in parallel with
capacitor C340 to return node BR-. Power to PFC controller is
applied to node PFB+ and to U1B pin 8. Output clock node PFCLK is
connected to U1B pin 7, to external buffer sub-circuit AMP (FIG.
29). Transistor Q305 collector is connected to the pin 2 node of
U1B. The base is connected in series through resistor R314 to
capacitor C318, then to the pin 2 node of U1B. The base is also
connected to [C310.parallel.R315], then to return node BR-. Emitter
of Q305 is connected to return node BR-. Transistor Q305 provides a
soft start compensation ramp to the controller error amp reducing
the stress and DC overshoot in the converter at power up. Capacitor
C341 is connected from U1 pin 2 to return node BR-. U1B pin 1 is
connected to pin PF1, capacitor C338 in series with resistor R339
to transistor Q305 collector and to U1 pin 2. Current switched by
PFC power switch Q1 (FIG. 4 & 3) is sensed by R26 (see FIG. 4).
Series resistors [R340+R341] to U1B pin 4 connect voltage developed
across R26. This voltage is compared to an internal 1.5-volt
reference, comparator output turns off the switch drive pin 7 of
U1B during times of high current that occur during startup or
during very high load or low line conditions. Capacitor C340 is
connected between U1 pin 4 to return node BR- filter high frequency
components. Schottky diode D308 connected between U1 pin 4 to
return node BR- protects the controller (U1 pin 4) substrate from
negative current injection. Maximum switch current value is set by
R26 over currents are automatically limited in each cycle by the
PFC controller. The rectified fullwave haversine at pin 3 of U1B is
multiplied by the error voltage on pin 2. The product is compared
to the magnetic element/switch current measured by R26 on pin 4.
Gate drive on pin 7 turns off when the sensed magnetic element
current increases to the current comparator level. This action has
the effect of modulating the switch Q1 "on" time tracking the AC
line voltage. External feedback networks are connected to node PF1.
In the event of a component failure in the primary feed network
such as IPFFB (FIG. 40), FBA (FIG. 40A), IFB (FIG. 40B) and FB1
(FIG. 41). The output voltage of the boost stage may rapidly
increase to destructive levels. Fast over voltage feedback networks
IOVFB (FIG. 40C) or OVP2 (FIG. 42B) increases the current into PF1
thereby limiting the output voltage to a safe level. In addition
latching type over voltage protection networks such as OVP (FIG.
42), OVP1 (FIG. 42A) and OVP2 (FIG. 42B) maybe used. The latching
type removes power to the control circuit thereby stopping the
boost action. The latching type networks require power to be cycled
to the converter to reset the latch. Modulating the voltage at PF1
changes the duty cycle of the PFC and the final output voltage. In
this way the PFC may be used as a pre-regulator to additional
output stages.
[0143] FIG. 25 Output rectifier and filter sub-circuit OUTA
[0144] FIG. 25 is a schematic of a full wave rectified output stage
and filter sub-circuit OUTA. The rectifier stage consists of diodes
D80 and D90. The filter consists of resistor R21, magnetic element
L30 and capacitors C26, C27, C28, C29, C30, C31 and C32.
21 Table Element Value/part number D80 40CTQ150 D90 40CTQ150 R21
100 ohms C26 500 pf C27 200 pf C28 0.1 uf C29 10,000 uf C30 10,000
uf C31 0.1 uf C32 200 pf L30 10 uh
[0145] Input node/pin C7B is connected to the high side of external
center-tapped magnetic element secondary winding.
[0146] Node C7B connects to anode of diode D8 and to capacitors C26
and C27 in the following arrangement. Capacitor C27 is connected
across diode D80, capacitor C26 is connected in series to R21.
Input node/pin C8B is connected to the low side of external
center-tapped magnetic element secondary winding. Pin C8B is
connected to anode of diode D9 and to resistor R21, capacitor C32
is connected across diode D90. Capacitors C27 and C32 is a small
value to reduce high frequency noise generated by rapid switching
the high speed rectifier D80 and D90 respectively. Capacitor C26
and resistor R21 are used to further dissipate high frequency
energy. Anode of diodes D80 and D90 is connected to parallel
capacitors C28.parallel.C29 and NSME L30. Capacitors C28 and C31
are solid dielectric types selected for low impedance to high
frequency signals. Capacitors C29 and C30 are larger polarized
types selected for low impedance at low frequencies and for energy
storage. Magnetic element L3 is connected to diode D8 cathode the
second terminal of L30 is connected to parallel capacitors C31 and
C30 and pin OUT+. Node OUT+ is the output positive and is connected
to external feedback sense line to isolated feedback network. The
other side of parallel capacitors
[C28.parallel.C29.parallel.C30.parallel.C31] is connected to pin
OUT- and the center-tap of the magnetic element secondary forming
the return node. The combination of capacitors [C2881 C29], L30 and
capacitors [C30.parallel.C31] form a low pass pi type filter.
Sub-circuit OUTA performs efficient fullwave rectification and
filtering.
[0147] FIG. 25A Output rectifier sub-circuit OUTB
[0148] FIG. 25A is a schematic of a full wave rectified output
stage. The rectifier stage consists of diodes D80 and D90 and
capacitors C931 and CG928.
22 Table Element Value/part number D80 40CTQ150 D90 40CTQ150 C928
.01 uf C931 10,000 uf
[0149] Input node/pin C7B is connected to high side of external
center-tapped magnetic element secondary winding. Node C7B connects
to anode of diode D80. Input node/pin C8B is connected to low side
of external center-tapped magnetic element secondary winding is
connected to anode of diode D90. Node OUT- is the negative output
and return line to the external isolated feedback network and load
not shown. Cathodes of diodes D80 and D90 are connected to parallel
capacitors C931 and C928. Capacitor C928 is a solid dielectric type
selected for low impedance to high frequency signals. Capacitor
C931 is a larger polarized selected for low impedance to low
frequency signals and for energy storage. Node OUT+ is the output
positive and is connected to external feedback sense line to
isolated feedback network. The other side of parallel capacitors
C928.parallel.C931 is connected to the center-tap of the magnetic
element secondary forming the node OUT-. The use of the NSME for
the push-pull magnetic element requires only minimal filtering
after the rectifiers.
[0150] FIG. 25B AC rectifier and filter sub-circuit OUTB
[0151] FIG. 25B is a schematic diagram of an alternate final output
rectifier and filter sub-circuit OUTB. The rectifier sub-circuit
OUTB comprises diodes D40, D41, D42 and D43 and capacitor C931 and
C928.
23 FIG 25B Table Element Value/part number D40 40CTQ150 D41
40CTQ150 D42 40CTQ150 D43 40CTQ150 C928 .01uf C931 10,000 uf
[0152] An AC or DC signal is connected to nodes C7B and C8b. Node
C7B connects diode D41 anode to D40 cathode. Node C8b connects
diode D42 anode to D43 cathode. Node OUT+ connects diode D42
cathode to D43 cathode. Node OUT- connects diode D40 anode to D43
anode. Diodes are selected to reliably block the expected line
voltage and current demands of the load. For low voltage outputs,
Schottky type diodes are used due to their low forward voltage
drop. Higher voltages would use high-speed silicon diodes due to
their ability to withstand high peak inverse voltage (PIV). The use
of the NSME for the push-pull magnetic element requires only
minimal filtering after the rectifiers. Capacitor C928 is shown
schematically as a single device. Capacitor C931 is a larger
polarized selected for low impedance to low frequency signals and
for energy storage a typical value may be 200 uF. To increase the
capacitance or reduces the output impedance multiple capacitors may
be used. C931 is a solid dielectric type and is selected for it's
low impedance to high frequencies. As is selected to reduces noise
for a particular operating frequency and power level. Capacitor
C928 is selected for the operating frequency and power level.
Sub-circuit OUTB performs AC to DC rectification and filtering at
slightly lower efficiency due to the extra junctions.
[0153] FIG. 26 Floating 18_Volt DC control power sub-circuit CP
[0154] Sub-circuit CP consists of diodes D501, D502 and D503,
resistor R507, regulator Q504, and capacitors C503, C504, C505,
C506, and C507.
24 Table Element Value/part number C503 .33 uF C504 100 uF D501
MURS120T3 C505 .33 uf Q504 LM7818A C508 100 uf C507 100 uf D503
MURS130T3 D502 MURS120T3
[0155] Node CT1A connects to anode of D503 and to the upper
external center tapped secondary winding. Node CT2A connects to
anode of D502 and to the lower external center tapped secondary
winding. Node CT0 connects to the external winding center tap. Node
CT0 is also the return line and it connects to Q504 pin 2, and
capacitors C503, C504, C505, C506, and C507. The cathode of each of
diodes D502 and D503 is connected to resistor R507. R507 is then
connected to the pin 1 (input) node of voltage regulator Q504.
Voltage regulator Q504 Pin 3 is the 18 vdc regulated DC output is
connected to the anode of blocking diode D501. Three-pin voltage
regulator Q504 is of the type LM7818 a common device made by a
number of manufacturers. Capacitors C503, C505, C506 are 0.1 uF
solid dielectric type and are used to filter high frequency ripple
and to prevent Q504 from oscillating. The junction of C503, C504
and D501 cathode is the output node CP1+. Isolated 18-volt DC is
available between nodes CT0 and CP+. Used for regulator circuits
and output switch drive during normal operation.
[0156] FIG. 27 second Floating 18_-Volt DC push-pull control power
sub-circuit CPA. Sub-circuit CPA consists of diodes D601, D602 and
D603, resistor R607, regulator B604 and capacitors C603, C604,
C605, C606, C607 and C608.
25 Table Element Value/part number C603 .33 uF C604 100 uF D601
MURS120T3 C605 .33 uF Q604 LM7818A C608 100 uF C607 .22 uF R607 7.5
ohms D603 MURS120T3 D602 MURS120T3
[0157] Node CT1B connects to anode of D603 and to the upper
external center tapped secondary winding. Node CT1B connects to
anode of D602 and to the lower external center tapped secondary
winding. Node CT20 connects to the external winding center tap.
Node CT0 is also the return line and it connects to Q604 pin 2, and
capacitors C603, C604, C605, C606, and C607. The cathode of each of
diodes D602 and D603 is connected to resistor R607. R607 is then
connected to the pin 1 (input) node of voltage regulator Q604.
Voltage regulator Q604 Pin 3 is the 18 vdc regulated DC output and
is connected to the anode of blocking diode D601. Capacitors C603,
C605, C606 are solid dielectric type and are used to filter high
frequency ripple and to prevent Q604 from oscillating. The junction
of C603, C604 and D601 cathode is the output node CP1+. Isolated
18-volt DC is available between nodes CT20 and CP2+. To be used for
regulator circuits and output switch drive during normal
operation.
[0158] FIG. 28 over temperature protection sub-circuit OTP
[0159] FIG. 28 is the main switch over temperature protection
sub-circuit OTP. The sub-circuit OTP comprises thermal switch and
resistors R711 and R712.
26 Table Element Value/part number THS1 67F105 (105C) R711 20 ohms
R712 20 ohms
[0160] Gate drive power is applied to input node GAP and to thermal
switch THS1. Maximum FET gate voltage requires the input power
voltage be less than 20 volts, the voltage selected was 18 volts.
The other side of THS1 is connected to parallel resistors
[R711.parallel.R712]. A single resistor may represent the
resistors. The figure depicts the surface mount arrangement. The
other side of [R711.parallel.R712] connects to output node TS+.
Normally closed thermal switch TS1 is in contact with main switch
transistor Q1. In the event of temperature greater than 105 C. THS1
opens, thus removing power to the buffer sub-circuit AMP1 (FIG. 29)
causing switch Q1 to default to a blocking state protecting the
boost switch should the optional cooling fan fail or the circuit
reach high temperatures. In this instant invention the speed up
buffer AMP (FIG. 29) non-saturating magnetics (FIG. 18, 18A and 19)
allows the main switch and to run cooler than prior art for a given
power level. When switch temperature returns to normal range THS1
will close, allowing the PFC to resume normal operation. Under
normal load and ambient temperatures the thermal switch THS1 should
never open.
[0161] FIG. 29 PFC Buffer Circuit sub-circuit AMP, AMP1, AMP2,
AMP3
[0162] Switch drive command from PFCLK (FIG. 23 and 24) or PWFM
(FIG. 33) control elements are connected to a gate buffer circuit.
The sub-circuit AMP is comprised of power FET Q702, Darlington pair
Q703, capacitors C709 and C715, and resistors R710 and R725.
27 Table Element Value/part number C715 1000 pf C709 33 uF Q702
NOS355NCT Q703 FZT705CT R710 0 ohms R725 22.1k ohms
[0163] DC Power is applied to node GAT+to transistor Q702 drain and
to capacitor C709, which goes to ground. Maximum gate voltage
requires the input power voltage must be less than 20 volts,
18-volts was selected. Input node GA1 is connected to the gate of
FET Q702 is connected to the base of BJT1 of the Darlington pair
Q703 and to capacitor C715. C715 is connected across the Darlington
pair from the base, pin 1, to the collectors, pins 2 and 4, Q703
collector node is also connected to ground. The emitter of BJT2 is
connected to the gate of FET Q1. The source of FET Q702 is
connected through small optional series resistor R710 to the gate
of the output switch or node GA2. Some power FET's under certain
load may tend to oscillate when driven from a low impedance source
such as this buffer. A small resistance of approximately 2 ohms or
less may be required with out significant slowing of the switch. In
most cases R710 is replaced with a zero ohm jumper. Resistor R725
is connected from node GA0 and source of Q702. The input switching
signal to node GAP is in range of 20 kHz to 600 kHz. Very fast "on"
times are realized by proving a low impedance to rapidly charge the
output switch gate connected to node GA2. Capacitor C709 provides
additional current when Q702 switches on. Transistor Q703 provides
low impedance to rapidly remove the charge from the gate greatly
reducing the "off" time. This particular topology provides output
switch rise times on the order of 10 ns, as compared to the
industry standard rise time of 250 ns. The corresponding fall time
is <10 nS, again as compared to an industry fall time of 200-300
ns (See FIG. 13 and 14). In the event the converter is operated at
very high ambient temperatures a thermal switch may be placed in
series with input power pin GA+. This allows the switch transistor
to be gracefully disabled. Sub-circuit AMP greatly reduces
switching losses allowing converter operation in some cases with
out the common prior art forced air-cooling.
[0164] FIG. 30 snubber sub-circuit SN
[0165] FIG. 30 is a schematic diagram of a snubber sub-circuit of
the invention. The snubber sub-circuit SN is comprised of diodes
D804 and D805 and resistors R800, R817, R818, and capacitors C814
and C819.
28 Table Element Value/part number R800 12 ohms R817 1 mohm R818 1
mohm C814 33 pF C819 560 pF D805 MUR160
[0166] Node SNL2 connects to the drain terminal of the external
output switch and to flyback side of the inductive load. Input node
SNL2 connects to R800 in series with capacitor C819 to node SNOUT.
Diode D805 anode is connected to node SNL2 with resistors
[R817.parallel.R818] in parallel with D805. Resistors R817 and R818
may be combined to a single resistor. The cathode of D805 is
connected to capacitor C814 that connects to node/pin SNL1. Node
SNL1 connects to the supply side of external load magnetic element.
The other leg of external magnetic element is connected to the
anode of D805 and the anode side of external flyback diode D4. The
one MEG ohm resistors R817 and R818 bleed the charge from C814
resetting it for the next cycle. Capacitor C819 and resistor R800
captures the high frequency event from the transition of external
flyback diode D4 and moves part of the energy into the external
holdup capacitor connected to node SNOUT. Since external flyback
diode D4 and D805 isolate the drain of the output switch, faster
switching occurs because the output switch does not have to slew
the extra capacitance of a typical drain/source connected snubber
circuit. Note that this circuit does not attempt to absorb the
flyback in large RC networks that convert useful energy to losses.
Nor does it attempt to stuff the flyback to ground, adding
capacitance and slowing the output switch and increasing switching
losses. This sub-circuit is used with it's mirror SNB (FIG. 32)
across the external push-pull switches. This design returns the
some of the flyback energy back to the input supply or output load.
The "snubbering" action slows the rise of the flyback giving time
for the external flyback diode to start conduction. The circuit
efficiently manages high frequency flyback pulses.
[0167] FIG. 30A diode snubber sub-circuit DSN
[0168] FIG. 30A is a schematic diagram of a diode snubber
sub-circuit of the invention. The snubber sub-circuit DSN is
comprised of diodes D51, D52, D53, D54 and D55 and capacitors C51,
C52, C53, C54 and C55.
29 Table Element Value/part number C51 220 pf 100 v C52 220 pf 100
v C53 220 pf 100 v C54 220 pf 100 v C55 220 pf 100 v D51 Schottky
1-2ns 100 v SMBSR1010MSCT D52 Schottky 1-2ns 100 v SMBSR1010MSCT
D53 Schottky 1-2ns 100 v SMBSR1010MSCT D54 Schottky 1-2ns 100 v
SMBSR1010MSCT D55 Schottky 1-2ns 100 v SMBSR1010MSCT
[0169] Pin SNL2 is connected to the anode of D51 the cathode of D51
is connected to the anode of D52 the cathode of D52 is connected to
the anode of D53 the cathode of D53 is connected to the anode of
D54 the cathode of D54 is connected to the anode of D55 the cathode
of D55 is connected to pin SNOUT. Capacitors are connected across
each diode forming a series parallel combination of
[D51.parallel.C51]+[D52.parallel-
.C52]+[D53.parallel.C53]+[D54.parallel.C54]+[D55.parallel.C55].
Node SNL2 connects to the drain terminal of the external output
switch and to flyback side of the inductive load. The external
fly-back rectifier diode D4 (FIG. 1, 3 and 4) anode is connected to
node SNL2. Node SNOUT connects to the storage capacitors
[C16.parallel.C17] (FIG. 1, 3 and 4) and to the cathode of the
flyback diode D4. External diode D4 in parallel with DSN forms a
hybrid diode. The Schottky diode has the desirable characteristics
of fast recovery time (less than 6 nanoseconds (6*10 -9)) and low
forward voltage drop (0.4-0.9 Volts) at high currents. The Schottky
diode suffers from limited reverse blocking voltage currently 100 V
maximum. Each diode will block 100V; the parallel capacitors
distribute the reverse voltage equally across the diode string. As
the reverse junction capacitance of each diode is less than 10 pf
much smaller than the parallel capacitor. Thus the reverse voltage
is nearly equally divided across the diodes. To guarantee even
voltage division 5% or better capacitor matching is required. High
precision is common and inexpensive for small capacitors. Different
blocking voltages may be achieved by adjusting the number of
diode/capacitor pairs. By way of example not as a limitation 500V
was selected. The main fly-back rectifier diode D4 will block high
voltages but suffers from long reverse recovery time 50-500
nanoseconds is common in fast recovery diodes. What is needed is a
diode with low voltage drop, high blocking voltage and very short
recovery time. The snubber DSN in parallel with the main fly-back
rectifier comes very close to that ideal diode. The total blocking
voltage is achieved by the adding the individual diode blocking
voltages. The recovery time is determined by the slowest diode in
the string often less than 5 nanoseconds. The low forward voltage
drop is achieved when the slower main rectifier begins conduction.
Low capacitance is also realized, as the capacitance is 1/5 of the
individual capacitors. This hybrid diode begins rectification
immediately after the main switch stops conduction and the
non-saturating magnetic begins releasing its energy. This
effectively limits the high voltage flyback over shoot to less than
40-70 volts. This keeps the switch well inside it's safe operating
area (SOA) allowing the switch to be run at higher voltages for
higher output power and additional efficiency gain, or to use a
less expensive lower voltage switch while keeping the same voltage
margins. Since external flyback diode D4 and D805 isolate the drain
of output switch, faster switching occurs because the output switch
does not have to slew the extra capacitance of the typical snubber
circuit. Note that this circuit does not attempt to absorb the
flyback in large RC networks that generate additional heat. Nor
does it attempt to stuff the flyback to ground, adding capacitance
and slowing the output switch, increasing switching losses.
Sub-circuit DSN may be used in parallel with any slower rectifier
such as flyback diode D4 to assist the main rectifier. This
providing additional protection to the switch and rectifying the
portion of the flyback pulse before the main rectifier begins
condition. That high frequency energy ends up as heat or radiated
noise.
[0170] FIG. 31 snubber sub-circuit SNA
[0171] FIG. 31 is a schematic diagram of a snubber sub-circuit of
the invention. The snubber sub-circuit SNA is comprised of resistor
R810 and R811 and capacitors C820 and C821.
30 Table Element Value/part number R810 500 pF C811 330 pF C820 12
ohm C821 10 ohm
[0172] Node SNAL connects to series resistor R810 to capacitor C820
to node SNA2 then to capacitor C821 and series resistor R811 to
node SNA3. Node SNAL connects to the external magnetic element
center tap. Node SNA2 connects to the drain terminal of the
external output switch and to flyback side of the inductive load.
Node SNA3 connects to the source terminal of the external output
switch. Resistor R810 and C820 attempt to absorb part of the
flyback to reduce voltage transients across the switch. Part of the
flyback is returned to ground by C821. This sub-circuit is used
with it is mirror SNA (FIG. 31) across the external push-pull
switches. The "snubbering" action slows the rise of the flyback
giving time for the external rectifier diodes D8 and D9 of FIG. 25
or 25A to start conduction. The circuit efficiently manages high
frequency flyback pulses.
[0173] FIG. 32 snubber sub-circuit SNB
[0174] FIG. 32 is a schematic diagram of a snubber sub-circuit of
the invention. The snubber sub-circuit SNB comprises resistor R820
and R821 and capacitors C840 and C841.
31TABLE FIG. 32 Element Value/part number C840 500 pF C841 330 pF
R820 12 ohm R821 10 ohm
[0175] Node SNB1 connects to series resistor R820 to capacitor C820
to node SNA2 to capacitor C841 and to series resistor R821 to node
SNB3. Node SNB1 connects to the external magnetic element center
tap. Node SNB2 connects to the drain terminal of the external
output switch and to flyback side of the inductive load. Node SNB3
connects to the source terminal of the external output switch.
Resistor R820 and C840 attempt to absorb part of the high frequency
flyback to reduce voltage transients across the switch. C841 and
R821 return part of the flyback to ground. The "snubbering" action
slows the rise of the flyback giving time for the external
rectifier diodes D8 and D9 of FIG. 25 or 25A to start conduction.
The circuit efficiently manages high frequency flyback pulses.
[0176] FIG. 33 Pulse/Frequency modulator PWFM
[0177] FIG. 33 is the inventions PWM (pulse width modulator) and FM
(frequency modulator) sub-circuit. Sub-circuit PWFM consists of
resistors R401, R402, R403, and R404 capacitors C401, C402, C403,
C404, C405 and C406, controller IC U400 and diode D401.
32TABLE FIG. 33 Element Value/part number R404 50k ohms C406 100 uf
C401 0.22 uF C403 0.01 uF C405 2200 pF C404 470 pF C402 0.22 uF
R403 50k ohms D401 RLS139 (low leakage) R401 2.2 MEG ohms R402 150k
ohms U400 MIC38C43
[0178] Control element U400 connects to a circuit with the
following series connections: from pin 1 to feedback pin PW1 then
to the wiper of adjustable resistor R404 to return node PWFM0.
Resistor R404 may be replaced with two fixed resistors. Capacitor
C403 is connected from pin 2 to pin 1. Capacitor C403 is used to
filter the error amp output. The upper half of resistor R404 is
connected to node REF1 pin 8 the 5.0-Volt internal reference.
Internal 5.0-volt reference U400 pin 8 or Node REF1 is connected to
the upper half of resistor R403 and through capacitor C402 to
return node PWFM0. The reference provides current to external feed
back networks. Wiper of R403 connects to node FM1 to pin 4, through
R402 to pin 3, and through C404 to return node PWFM0. Resistor R403
may be replaced with two fixed resistors. Pulse width timing
capacitor C404 connects pin 3 to return node PWFM0. Low leakage
diode D401 anode is connected to pin 3 cathode to output pin 6 node
CLK. Resistor R404 sets the nominal pulse width of output pin 6
node CLK. The pulse width can be adjusted from 0 (off) to 95%.
Resistor R403 and C404 determine the nominal operating frequency.
With application of power 20-volts between Nodes PWFM+and PWFM0
controller U400 generates an internal 5.0 reference voltage to pin
7 node REF1. Output pin 6 node CLK is set high approximately
20-volts (see oscillograph trace G6 segment 60 FIG. 34). C404
starts to charge through R401 until the voltage across C404 at pin
3 reaches the comparator level (see oscillograph trace G1 segment
61 FIG. 34) at resetting the pin 6 low (see oscillograph trace G6
segment 62 FIG. 34). Capacitor C404 rapidly discharges though D401
(see oscillograph trace G1 segment 63 FIG. 34). Pin 3 remains
0.6-volts above PWFM0 node during the period pin 6 is low (see
oscillograph trace G1 segment 64 FIG. 34). On the rising edge of
pin 6 capacitor C405 begins to rapidly charge until the voltage in
pin 4 reaches the internal comparator level (see oscillograph trace
G4 segment 65 FIG. 34). The comparator triggers internal transistor
to rapidly discharge C404 (see oscillograph trace G4 segment 66
FIG. 34). The cycle repeats with output pin 6 being set high.
External feedback current applied to U400 pin 1 and node PW1 (see
oscillograph trace G1 segment FIG. 34) follows the actual output
voltage. Oscillograph trace G1 segment 67 (FIG. 34) is the period
when the output switch conducting storing energy in the NSME.
Oscillograph trace G1 segment 68 (FIG. 34) is the period when the
output switch is off allowing storing energy in the NSME to be
transferred to the storage capacitor. Application of external
current source or feed back network to pin 1 or node PW1 allows the
pulse width to be modulated. Removing current from PW1 lowers the
comparator level causing the comparator to trigger at lower
voltages across C404 reducing the pulse width. Introducing current
into node PW1 increases pulse width from nominal to maximum of 95%.
Resistor R404 and C404 determine the nominal pulse width. This
design allows the CLK output to be pulse width modulated.
Application of external feed back network to pin 4 or node FW1
allows the frequency to be modulated. Removing current from FW1
slows the charging of C405. Longer charging time lowers the
frequency from the nominal setting. This arrangement allows the CLK
output to frequency modulated. When used with a resonant
controller, R403 and C405 determine the nominal frequency typically
equal to the tank resonant frequency. The external feedback is
configured to lower the frequency from nominal (maximum output) to
zero frequency "off". When used as a pulse-width controller the
nominal is set to maximum pulse width of about 90% feedback reduces
the pulse-width. Sub-circuit PWFM may be simultaneously frequency
and pulse width modulated. This configuration and mode of operation
is unique to this instant invention. Feeding back of the output to
the error amplifier is a unique mode of operation for control
element U400. Sub-circuit PWFM combines large dynamic range,
precise control and fast response.
[0179] FIG. 34 Oscillograph traces of the PWFM (FIG. 33) controller
in the pulse-width modulation mode.
[0180] FIG. 35 Oscillograph trace of the TCTP (FIG. 8) resonant
converter primary voltage. FIG. 35 is an oscillograph trace of the
voltage developed across capacitor C10 (FIG. 8). In this embodiment
the supply VBAT was only 18-volts. The primary 100 (FIG. 18)
inductance 203 uH was achieved by 55 turns on a 26 u 2.28 oz.
KoolMu magnetic element 101. The secondary winding 103 (FIG. 18) is
15 turns on core 101. A 5.5-watt load is connected to winding 103.
The NSME primary 100 (FIG. 18) developed an excitation voltage of
229 volts peak more than 10 times VBAT. Tank converters TCTP and
TCSSC (FIG. 7) take advantage of the desirable properties of the
non-saturating magnetic to develop large flux biases. The useful
large flux may harvested into useful power by addition of "flux
nets" windings to the magnetic element.
[0181] FIG. 36 Regulated 18_Volt DC control power sub-circuit REG
Sub-circuit REG consists of resistor R517, regulator Q514 and
capacitors C514, C515, C516, C518, and C517.
33TABLE FIG. 36 Element Value/part number Q514 LM7818 C515 0.01 uF
C517 0.01 uF C514 10 uF C518 10 uF
[0182] Pin REG0 connects to the external power source return. Node
REG0 is also the return line it connects to Q514 pin 2, and
capacitors C518, C514, C515, and C517. Resistor R517 is connected
to the pin 1 (input) node of voltage regulator Q514 and to input
pin RIN+. Voltage regulator Q514 Pin 3 is the 18 vdc regulated DC
output is connected to the capacitors C515, C514 and output pin
18V. Capacitors C515, C517 are solid dielectric type is used to
filter high frequency ripple and to prevent Q514 from oscillating.
Sub-circuit REG provides regulated power for control circuits and
output switch buffer AMP (FIG. 29).
[0183] FIG. 37 is a schematic for a non-isolated high side switch
buck converter sub-circuit HSBK. FIG. 37 is a non-isolated high
side switch buck converter sub-circuit HSBK. This converter
topology consists of a non-isolated high efficiency buck stage,
which provides regulated power to an efficient push-pull isolation
stage. Sub-circuit HSBK consists of diode D8, capacitor C8, FET
transistor Q31, sub-circuit TCTP (FIG. 8), sub-circuit BL1, (FIG.
18B), sub-circuit IFB (FIG. 40B), sub-circuit AMP (FIG. 29) and
sub-circuit PWFM (FIG. 33).
34TABLE FIG. 37 Element Value/part number C68 250 uf D68 MUR820 Q31
IRF540N
[0184] External power source VBAT connects to pins DCIN+ and DCIN-.
Pin DCIN+ connects to transistor Q31 source, sub-circuit PWFM pin
PWFM0, sub-circuit AMP pin GA0, and sub-circuit IFB pin FBE,
sub-circuit TCTP pins DCIN+ and B-. Regulated 18-volt output from
sub-circuit TCTP pin B+ connects to sub-circuit AMP pin GA+and to
sub-circuit PWFM pin PWFM+. This provides the positive gate drive
relative to the source of Q31. Power source VBAT return is
connected to pin DCIN-, sub-circuit TCTP pin DCIN-, diode D68
anode, capacitor C68, RLOAD, sub-circuit IFB pin OUT-, output pin
B- and ground/return node GND. Sub-circuit PWFM is designed for
adjustable pulse-width operation from 0 to 90%, maximum pulse width
occurs with no feedback current to pin PW1. Increasing the feedback
current reduces the pulse-width and output voltage from converter
HSBK. Sub-circuit PWFM clock/PWM output pin CLK is connected to the
input pin GA1 of buffer sub-circuit AMP. The output of sub-circuit
AMP pin GA2 is connected to the gate of Q31. The drain of Q31 is
connected to sub-circuit BL1 pin P1B and the cathode of D68. Pin
P1A of sub-circuit BL1, is connected to capacitor C8, sub-circuit
IFB pin OUT- and RLOAD. With sub-circuit PWFM pin CLK high buffer
AMP output pin GA2 charges the gate of transistor switch Q31.
Switch Q31 conducts charging capacitor C68 through NSME BL1 from
source VBAT and storing energy in BL1. Feedback output pin FBC from
sub-circuit IFB is connected to sub-circuit PWFM pulse-width
adjustment pin PW1. As the output voltage reaches the designed
level sub-circuit IFB removes current from PWl commanding PWFM to
reduce the pulse-width or on time of signal CLK. After sub-circuit
PWFM reaches the commanded pulse-width PWFM switches output pin CLK
low turning off Q31 stopping the current into BL1. The stored
energy is released from NSME BL1, into the now forward biased diode
D68 charging capacitor C68. By modulating the on time of switch Q31
the converter "bucks" applied voltage and efficiently regulates to
a lower voltage. Regulated voltage is developed across Nodes B- and
B+. Sub-circuit IFB provides the isolated feedback voltage to the
sub-circuit PWFM. When sub-circuit IFB senses the converter output
(nodes B+ and B-) is at the designed voltage more current is
conducted by the phototransistor. Sinking current from PM1 commands
the PWFM to a shorter pulse-width thus reducing the converter
output voltage. In the event the feedback signal from IFB commands
the PWFM to minimum output. Gate drive to switch Q31 is removed
stopping all buck activity capacitor C68 discharges through RLOAD.
Input current from VBAT is sinusoidal making the converter very
quiet. As such the switch Q31 is not exposed to large current
spikes common to saturating magnetic prior art. Thus placing less
stress on the switches thereby increasing the MTBF. Sub-circuit
HSBK takes advantage of the desirable properties of the NSME in
this converter topology.
[0185] FIG. 38 is a schematic for an isolated two-stage low side
switch buck converter sub-circuit LSBKPP. This converter topology
consists of a high efficiency low-side switch buck stage, which
provides regulated power to an efficient push-pull isolation stage.
An efficient center-tap fullwave rectifier provides rectification.
Sub-circuit LSBKPP consists of diode D46, capacitor C46, FET
transistor Q141, sub-circuit REG (FIG. 36), sub-circuit OUTB (FIG.
25A), sub-circuit BL1, (FIG. 18B), sub-circuit TCTP (FIG. 8),
sub-circuit IFB (FIG. 40B), sub-circuit AMP (FIG. 29), sub-circuit
DCAC1, and sub-circuit PWFM (FIG. 33).
35TABLE FIG. 38 Element Value/part number C46 250 uf D46 MUR820
Q141 IRFS40N
[0186] External power source VBAT connects to pins DCIN+ and DCIN-.
From pin DCIN+ connects to sub-circuit REG pin RIN+, D46 cathode,
capacitor C46, sub-circuit TCTP (FIG. 8) pin DCIN+, and sub-circuit
DCAC1 pin DC+. Voltage regulator sub-circuit REG output pin +18V
connects to sub-circuit AMP pin GA+ and to sub-circuit PWFM pin
PWFM+. Sub-circuit REG provides regulated low voltage power to the
controller and to the main switch buffer. VBAT negative is
connected to pin DCIN- and ground return node GND. Node GND
connects to sub-circuit PWFM pin PWFM0, sub-circuit AMP pin GA0,
Q141 source, sub-circuit IFB pin FBE, sub-circuit REG pin REG0 and
sub-circuit TCTP pin DCIN-. Sub-circuit PWFM (FIG. 33) is designed
for variable pulse width operation. The nominal frequency is
between 20-600 Khz PWFM is configured for maximum pulse width 90%
(maximum buck voltage) with no feedback current from sub-circuit
IFB. Increasing the feedback current reduces the Q111 on time
reducing the voltage to the push-pull stage and the output from
converter LSBKPP. Sub-circuit PWFM clock output pin CLK is
connected to the input pin GA1 of buffer sub-circuit AMP (FIG. 29).
The output of switch speed up buffer sub-circuit AMP pin GA2 is
connected to the gate of Q141. Floating isolated 18-volt power from
sub-circuit TCTP pin B+ connects to sub-circuit DCAC1 pin P18V. The
drain of Q141 is connected to sub-circuit BL1, pin P1A and the
anode of D46. The return line of sub-circuit DCAC1 pin DC- connects
to sub-circuit BL1, pin P1B, sub-circuit TCTP pin B- and C46. With
sub-circuit PWFM pin CLK high buffer AMP output pin GA2 charges the
gate of transistor switch Q141. Switch Q141 conducts reverse
biasing diode D46; capacitor C46 starts charging through NSME BL1,
from source VBAT. During the time Q141 is conducting, energy is
stored in NSME sub-circuit BL1. Charging C46 provides power to
final push-pull converter stage DCAC1. The output of the output
rectifier sub-circuit OUTB is connected to feedback sub-circuit IFB
output pin FBC from sub-circuit IFB is connected to sub-circuit
PWFM pulse-width adjustment pin PW1. Sub-circuit IFB removes
current from PW1 commanding PWFM to reduce the pulse-width or on
time of signal CLK. After sub-circuit PWFM reaches the commanded
pulse-width PFFM switches CLK low turning off Q141 stopping the
current into BL1. The energy is released from NSME BL1, into the
now forward biased flyback diode D46 charging capacitor C46. By
modulating the on time of switch Q141 the converter voltage is
regulated. Regulated voltage is developed across C46 Nodes DC+ and
GND. Providing energy to the isolated constant frequency push-pull
DC to AC converter sub-circuit DCAC1 (FIG. 2). Sub-circuit DCAC1
provides efficient conversion of the regulated buck voltage to a
higher or lower voltage set by the magnetic element winding
sub-circuit PPT1 (FIG. 19) ratio. The center tap of the push-pull
output magnetic is connected to, sub-circuit OUTB pin OUT-, RLOAD,
sub-circuit IFB pin OUT- and the pin OUT- forming the return line
for the load and feedback network. Output of sub-circuit DCAC1 pin
ACH is connected to sub-circuit OUTB pin C7B. Output of sub-circuit
DCAC1 pin ACL is connected to sub-circuit OUTB pin C8B. Sub-circuit
OUTB provides rectification of the AC power generated by
sub-circuit DCAC1. As the non-saturation magnetic converter is very
quite minimal filtering is required by OUTB. This further reduces
cost and improves efficiency as losses to filter components are
minimized. Sub-circuit IFB provides the isolated feedback current
to the sub-circuit PWFM. When sub-circuit IFB senses the converter
output (nodes OUT+ and OUT-) is greater than the designed/desired
voltage, current is removed from node PM1. Sinking current from PM1
commands the PWFM to a shorter pulse-width thus increasing the buck
action and reducing the first stage converter output voltage. In
the event the feedback signal from IFB commands the PWFM to minimum
output. Gate drive to switch Q141 is removed stopping all buck
activity capacitor discharging C46. Input current from VBAT to
charge C46 is sinusoidal making the converter very quiet. In
addition the switch Q141 is not exposed a potentially destructive
current spike. Placing less stress on the switches thereby
increasing the MTBF. Sub-circuit LSBKPP takes advantage of the
desirable properties of the NSME in this converter topology.
Adjusting the NSME BL1, (FIG. 18B) sets the amount of buck voltage
available to the final push-pull isolation stage. Greater
efficiencies are achieved at higher voltages. The final output
voltage is set by the turns ratio of the push-pull element PPT1
(FIG. 19). Converter LSBKPP provides efficient conversion from high
voltage sources into high current isolated output.
[0187] FIG. 39 is a schematic for an isolated two-stage low side
switch buck converter sub-circuit LSBKPPBR. This converter topology
consists of a non-isolated high efficiency low-side switch buck
stage, which provides regulated power to an efficient push-pull
isolation stage. A fullwave bridge rectifier provides
rectification. Sub-circuit LSBKPPBR consists of diode D6, capacitor
C6, FET transistor Q111, sub-circuit REG (FIG. 36), sub-circuit
OUTBB (FIG. 25B), sub-circuit BL1, (FIG. 18B), sub-circuit TCTP
(FIG. 8), sub-circuit IFB (FIG. 40B), sub-circuit AMP (FIG. 29),
sub-circuit DCAC1 (FIG. 2), and sub-circuit PWFM (FIG. 33).
36TABLE FIG. 39 Element Value/part number C6 250 uf D6 MUR820 Q111
IRFP
[0188] External power source VBAT connects to pins DCIN+ and DCIN-.
From pin DCIN+ connects to sub-circuit REG pin RIN+, D6 cathode,
capacitor C6, sub-circuit TCTP (FIG. 8) pin DCIN+, and sub-circuit
DCAC1 pin DC+. Voltage regulator sub-circuit REG output pin +18V
connects to sub-circuit AMP pin GA+ and to sub-circuit PWFM pin
PWFM+. Sub-circuit REG provides regulated low voltage power to the
controller and to the main switch buffer. VBAT negative is
connected to pin DCIN- connects to sub-circuit PWFM pin PWFM0,
sub-circuit AMP pin GA0, Q111 source, sub-circuit IFB pin FBE,
sub-circuit REG pin REG0, sub-circuit TCTP pin DCIN-. Sub-circuit
PWFM (FIG. 33) is designed for variable pulse width operation. The
nominal frequency is between 20-600 Khz PWFM is configured for
maximum pulse width 90% (maximum buck voltage) with no feedback
current from sub-circuit IFB. Increasing the feedback current
reduces the Q111 on time reducing the voltage to the push-pull
stage and the output from converter LSBKPPBR. Sub-circuit PWFM
clock output pin CLK is connected to the input pin GA1 of buffer
sub-circuit AMP (FIG. 29). The output of switch speed up buffer
sub-circuit AMP pin GA2 is connected to the gate of Q111. Floating
isolated 18-volt power from sub-circuit TCTP pin B+ connects to
sub-circuit DCAC1 pin P18V. The drain of Q111 is connected to
sub-circuit BL1 pin PA1 and the anode of D6. The return line of
sub-circuit DCAC1 pin DC-connects to sub-circuit BL1, pin P1B,
sub-circuit TCTP pin B- and C6. With sub-circuit PWFM pin CLK high
buffer AMP output pin GA2 charges the gate of transistor switch
Q111. Switch Q111 conducts reverse biasing diode D6; capacitor C6
starts charging through NSME BL1 from source VBAT. During the time
Q111 is conducting, energy is stored in NSME sub-circuit BL1.
Charging C6 provides power to final push-pull converter stage
DCAC1. The output of the output rectifier sub-circuit OUTBB is
connected to feedback sub-circuit IPB output pin FBC from
sub-circuit IFB is connected to sub-circuit PWFM pulse-width
adjustment pin PW1. Sub-circuit IFB removes current from PWl
commanding PWFM to reduce the pulse-width or on time of signal CLK.
After sub-circuit PWFM reaches the commanded pulse-width PFFM
switches CLK low turning off Q111 stopping the current into BL1.
The energy is released from NSME BL1 into the now forward biased
flyback diode D6 charging capacitor C6. By modulating the on time
of switch Q111 the converter voltage is regulated. Regulated
voltage is developed across C6 nodes DC+ and DC-. Providing energy
to the isolated constant frequency push-pull DC to AC converter
sub-circuit DCAC1 (FIG. 2). Sub-circuit DCAC1 provides efficient
conversion of the regulated buck voltage to a higher or lower
voltage set by the magnetic element winding sub-circuit PPT1 (FIG.
19) ratio. The return node of the sub-circuit OUTBB pin OUT- is
connected to RLOAD, sub-circuit DCAC1 pin AC0, sub-circuit IFB pin
OUT- and the pin OUT-. Node OUT- is the return line for the load
and feedback network. Output of sub-circuit DCAC1 pin ACH is
connected to sub-circuit OUTBB pin C7B. Output of sub-circuit DCAC1
pin ACL is connected to sub-circuit OUTBB pin C8B. Sub-circuit
OUTBB provides rectification of the AC power generated by
sub-circuit DCAC1. As the disclosed non-saturation magnetic
converter has minimal output ripple, less filtering is required by
OUTBB. This further reduces cost and improves efficiency as losses
in filter components are minimized. Sub-circuit IFB provides the
isolated feedback current to the sub-circuit PWFM. Open collector
output of IFB pin FBC connects to PWFM pin PW1. When sub-circuit
IFB senses the converter output (nodes OUT+ and OUT-) is greater
than the designed/desired voltage, current is removed from node
PM1. Sinking current from PM1 commands the PWFM to a shorter
pulse-width thus increasing the buck action and reducing the first
stage converter output voltage. In the event the feedback signal
from IFB commands the PWFM to minimum output. Gate drive to switch
Q111 is removed stopping all buck activity capacitor discharging
C6. As the NSME does not saturate the destructive noisy current
spikes common to prior art are absent. Input current from VBAT to
charge C6 is sinusoidal making the converter very quiet. In
addition the switch Q111 is not exposed a potentially destructive
current spike. Placing less stress on the switches thereby
increasing the MTBF. Sub-circuit LSBKPPBR takes advantage of the
desirable properties of the NSME in this converter topology.
Adjusting the NSME BL1, (FIG. 18B) sets the amount of buck voltage
available to the final push-pull isolation stage. Greater
efficiencies are achieved at higher voltages. The final output
voltage is set by the turns ratio of the push-pull element PPT1
(FIG. 19). Converter LSBKPPBR provides efficient conversion from
high voltage sources such as high power factor AC to DC converters
such as sub-circuit ACDCPF (FIG. 4).
[0189] FIG. 40 PFC over voltage feed back sub-circuit IPFFB
[0190] FIG. 40 is the schematic of the inventions isolated over
voltage feed back network sub-circuit IPFFB. Sub-circuit IPFFB
consists of Resistors R926, R927, R928, R929 and R930, capacitor
C927, zener diodes D928 and D903, transistor Q915 and opto-isolator
U903.
37TABLE FIG. 40 Element Value/part number U903 NEC2501 Q915
FZT705CT D903 ML5248B (18 v) D928 1SMB5956BT3 (200 v) R926 20k ohms
R927 10k ohms R928 10k ohms R929 10k ohms R930 20k ohms
[0191] Node PF+ connects through resistor R927 to cathode of D903
and anode of opto-isolator U903. Cathode of diode D903 is connected
to pin PF+. Resistor R928 is connected from anode of D928 to base
of Q915. Capacitor C927 is connected in parallel with zener diode
D903. Resistor R928 limits maximum base current. Resistor R929 is
connected between base and emitter of Q915. Resistor R929 is used
to shunt excess zener leakage current from the base common in high
voltage diodes. Two hundred-volt zener diode cathodes D928 are
connected to pin PF+. Anode of D928 is connected to R930 and R928.
Resistor R930 provides a path for leakage current from 200-volt
zener D928. Resistor R926 limits the maximum current to U903
internal light emitting diode to about 10 ma. Resistor R927 sets
the maximum zener current at maximum boost voltage of approximately
200-volts to 20 ma. Transistor Q915 is biased off when the voltage
from node PF+ and PF- is less than the zener voltage of 200-volts.
Transistor is in a cutoff or non-conducting state no current is
injected to U903 LED. The internal phototransistor is also in a
non-conducting state. The attached external control sub-circuit is
not commanded to change its output. With 200 volts or more applied
to nodes PF+ and PF- reverse biased zener diode D928 injects
current into the base of Q915. Resistor R927, capacitor C927 and
diode D903 provide 18-volts to the collector of Q915. Transistor
Q915 conducts current into U903 LED injecting base current into the
U903 phototransistor. Modulating the LED current is reflected as
variable impedance between FBC and FBE. This phototransistor may be
connected as a variable current source or impedance. This
sub-circuit senses excessive boost voltage and quickly feeds back
to the control sub-circuit (See PFA (FIG. 23), PFB (FIG. 24) or
(PWFM FIG. 33)) automatically reducing the boost voltage.
[0192] FIG. 40A is a schematic diagram of the non-isolated boost
output voltage feed back sub-circuit FBA. Sub-circuit FBA consists
of Resistors R1120, R1121, R1122, R1123 and R1124.
38TABLE FIG. 40A Element Value/part number R1123 499k ohms R1124
499k ohms R1122 6.65k ohms R1121 499k ohms R1120 1 MEG ohms
[0193] Input node PF+ connected to series resistor [R1123+R1124]
then to parallel resistors [R20.parallel.R21.parallel.R22] to the
return node BR-. Resistors R1120, R1121, R1122, R1123 and R1124
values are selected for a nominal input voltage of 385-volts and
output feed back voltage of 3.85. (See oscillograph G1 FIG. 34)
Resistors R1120, R1121, R1122, R1123 and R1124 are shown in surface
mount configuration but can be combined into two thru
hole-resistors. Feedback output node PF1 is connected to node PF1
of sub-circuit PFA (FIG. 23) or PFB (FIG. 24). Return pin BR- is
connected to BR- of PFA (FIG. 23) or PFB (FIG. 24). Nodes FBE and
FBC it may also be connected between nodes FM1 pin PWFM0 or PW1 pin
PWFM0 of control sub-circuit PWFM (FIG. 33).
[0194] FIG. 40B output voltage feed back sub-circuit IFB
[0195] FIG. 40B is the schematic of the inventions isolated low
voltage feed back network sub-circuit FBA. Sub-circuit IFB consists
of Resistors R900, R901 and R902, zener diode D900, Darlington
transistor Q900 and opto-isolator U900.
39TABLE FIG. 40B Element Value/part number U900 NEC2501 Q900
FZT705CT D900 1N5261BDICT R900 1k ohms R902 4k ohms R901 40k
ohms
[0196] Node OUT+ connects cathode of D900 to R901. Anode of diode
D900 is connected to series resistor R900 to base of Darlington
transistor Q900. Resistor R902 is connected from base to emitter to
Q900. Resistor R901 connects to anode of opto-isolator U900 LED
(light emitting diode) the cathode is connected to Q900 collector.
Emitter of Q900 is the return current path and connects to pin/node
OUT-. Resistor R901 limits the maximum current to U900 internal
light emitting diode to 20 ma. Resistor R902 shunts some of the
zener leakage current from the base. Zener diode voltage selection
sets the converter output voltage a typical value maybe 48-volts.
The zener voltage is the final desired output minus two base
emitter junction drops (1.4V). Once the OUT+ node reaches the zener
voltage a small base current biases Q900 into a conducting state
turning"on" opto-isolator U900 internal LED. Resistor R900 limits
the maximum base current to Q900. Resistors R900 and R901 are
selected to bias Darlington transistor Q900 collector current with
nominal voltage across nodes OUT+ and OUT-. Change in voltage
between OUT+ and OUT- modulates the opto-isolator U900 LED current
in turn changing the base current of U900 internal photo
transistor. Phototransistor emitter is node FBE collector is node
FBC. Modulating the LED current is reflected as variable impedance
between FBC and FBE. This phototransistor may be connected as a
variable current source or impedance. When used with control
sub-circuit PFA (FIG. 23), PFB (FIG. 24) or (PWFM FIG. 33) the
phototransistor is connected as a current shunt. Higher voltage
applied to OUT+ and OUT- nodes increases the feedback shunt current
commanding the control sub-circuit (See PFA (FIG. 23) or PFB (FIG.
24) or PWFM (FIG. 33)) to reduce the pulse-width or frequency. IFB
accomplishes high speed feed back due to the very high gain of the
Darlington transistor and the rapid response of the internal
converter stage(s) active ripple reduction and excellent load
regulation are achieved.
[0197] FIG. 40C is the schematic of the alternate PFC isolated over
voltage feed back network sub-circuit IOVFB. Sub-circuit IOVFB
consists of resistors of R917, R938, R939 and R940, diode D911,
Darlington transistor Q914 and opto-isolator U905.
40TABLE FIG. 40C Element Value/part number U905 NEC2501 Q914
FZT705CT R938 160k ohms R939 70k ohms D911 1N5261BOTCT R940 50k
ohms R917 40k ohms
[0198] The output of the PFC at pin PF+ is connected to R917 then
to collector of Q914. Resistor R917 sets the maximum current to
U905 light emitting diode. Resistor R938 is connected from return
node PF+ to zener diode D911 cathode and R938. Resistor R939 is
connected from return node PF- to zener diode D911 cathode and
R938. Anode of D911 is connected to wiper arm of adjustable
resistor R940. One leg of R940 is connected to the base of
transistor Q914 the other to R939 and U905 LED anode and R939.
Emitter of Q914 is connected to anode of U904. Adjustable resistor
R940 sets the maximum or trip voltage before transistor Q914 is
biased on. Providing current to U905 LED. Phototransistor emitter
is node FBE collector is node FBC. Modulating the LED current is
reflected as variable impedance between FBC and FBE. This
phototransistor is normally connected as a shunt to force the
control element to a minimum output. This sub-circuit senses the
boost voltage and feeds back to the PFC. Where excessive boost
voltage forces the PFC to automatically reduce the boost
voltage.
[0199] FIG. 41 output voltage feed back sub-circuit FBI
[0200] FIG. 41 is the schematic of the alternate low voltage feed
back network sub-circuit FBI. Sub-circuit FBI consists of Resistors
R81, R82 and R83, zener diode D80, NPN transistor Q80 and capacitor
C80.
41 Table Element Value/part number R81 1 k ohms D80 Zener Voltage =
(Desired Output-0.65 V) Q80 BCX70KCT C80 1000 pf R82 1 k ohms R83
715 k ohms
[0201] Node OUT+ connects cathode of D80. Anode of diode D80 is
connected to through resistor R83 to OUT- and resistor R82 to base
of transistor Q80. Capacitor C80 is connected from base to pin
OUT-. Capacitor C80 bypasses high frequency to noise to OUT-.
Resistor R81 is connected from emitter of Q80 to node OUT-.
Resistor R81 adds local negative feedback to reduces the effects of
variation in transistor gain. Collector of Q80 is connected to pin
FBC. The return current node connects to pins FBE and OUT-.
Resistor R82 limits the maximum base current protecting Q80.
Resistor R83 shunts some of the zener leakage current from the
base. Zener diode voltage selection sets the converter output
voltage a typical value maybe 48-volts. The zener voltage is the
final desired output minus one base emitter junction drop
(0.65-Volts). When the OUT+ node reaches the nominal level reverse
biased zener starts to conduct injecting a small base current into
Q80. Biasing transistor into a conducting state. Change in voltage
between OUT+ and OUT- modulates Q80 collector current. During
normal operation the zener diode is biased at it's knee thus small
changes in voltage result in relatively large collector current
changes. When sub-circuit FBI used with control sub-circuit PFA
(FIG. 23), PFB (FIG. 24) or (FIG. 33) the transistor is connected
as a current shunt. Higher voltage applied to OUT+ and OUT- nodes
increases the feedback shunt current commanding the control
sub-circuit (See PFA (FIG. 23) or PFB (FIG. 24) or PWFM (FIG. 33)
to reduce the pulse-width or frequency. Sub-circuit FBI provides
high-speed feedback and gain to ripple components. With the rapid
response of the internal converter stage(s) active ripple reduction
and excellent load regulation are achieved.
[0202] FIG. 42 over voltage protection sub-circuit OVP1
[0203] FIG. 42 is the schematic of the inventions over voltage
protection embodiment sub-circuit OVP1. Sub-circuit OVP1 consists
of SCR (silicon controlled rectifier) SCR1200, resistor R1200,
capacitor C1200 and zener diodes D1200, D1202 and D1203.
42 Table Element Value/part number SCR1200 MCR265-10 D1203
BZT03-C200 (200 V) D1202 BZT03-C200 (200 V) D1200 IN4753 (5.1 v)
C1200 220 pf R1200 10, 0k ohms
[0204] Input pin PF+ is connected to cathode of zener diode D1203,
anode of D1203 is connected to series zener diodes [D1202+D1200]
then to gate of SCR1200. Noise attenuation network of
[R1200.parallel.C1200] is connected from SCR SCR1200 gate to the
return node BR-. Diodes D1102 and D1103 are both 200-volt; D1101 is
a 5.1-volt type the sum of the zener voltages set the trip point of
the OVP at 405-volts. Other trip voltages may be implemented by
selecting other zener diode combinations. Capacitor C1200 and R1200
prevents leakage current and transients from accidentally tripping
the OVP. In the event of very high AC line voltages or a component
failure in a feed back loop (FIG. 40A, 40B, 40C. or 40) The boost
voltage may quickly rise increase to levels dangerous to the output
switch or output storage capacitors. When the output boost voltage
of the at node PF+ rises above 405V, zener diodes D1203, D1202 and
D1200 conduct a small current into the gate of SCR1200 turning
SCR1200 on. Turning SCR1200 on places a low impedance path across
the AC line through the rectifier sub-circuit BR (FIG. 22). SCR1200
and bridge rectifier diodes must be selected to withstand the short
circuit currents that may exceed 100 amperes until the input fuse
opens. Thus quickly limiting the boost output voltage to a safe
level. This circuit should never operate under normal AC line
voltages. By changing zener voltages this sub-circuit would also be
suitable for use in the across the rectifier output to protect the
load from an over voltage condition. Sub-circuits OVP1 shuts down
the converter with out opening the line fuse. Sub-circuit OVP may
be used in combination with OVP1 (FIG. 42A) as a fail-safe back up
for critical loads.
[0205] FIG. 42A over voltage protection sub-circuit OVP1
[0206] FIG. 42A is the schematic of the inventions over voltage
protection embodiment sub-circuit OVP2. Sub-circuit OVP2 consists
of SCRs (silicon controlled rectifier) SCR1101 and SCR1100,
resistors R1101 and R1102, capacitors C1100 and C1101 and zener
diodes D1100, D1102 and D1103.
43 Table Element Value/part number SCR1101 S101E (Teccor) SCR1100
S601E (Teccor) D1103 BZT03-C200 (200 V) D1102 BZT03-C200 (200 V)
D1100 IN4753 (5.1 v) R1100 16000 R1101 5.1 K ohms R1102 5.1 K ohms
C1100 1200 pf C1101 1200 pf
[0207] Anode of SCR1101 is node/pin CP18V+ that is connected to
external control DC source. Return node BR- is connected to SCR1101
cathode and capacitor C1100. Input node PF+ is connected to cathode
of zener diode D1103 and to series resistor R1100 then to anode of
SCR SCR1102. The anode of D1103 is connected to the cathode of
D1102. The anode of D1102 is connected to the cathode of D1100. The
cathode of SCR1100 is connected to the gate of SCR1101. The anode
of D1103 is connected to series zener diodes [D1102 +D1100] then to
capacitor C1100 then to the return node BR-. Capacitor
[C1200.parallel.R1200] prevents leakage current and transients from
accidentally tripping OVPB. In the event of very high AC line
voltages or a component failure in a feed back loop (IPFFB FIG.
40A, FBA 40B, IFB 40C. or FBI FIG. 41) The boost voltage may
quickly rise increase to levels dangerous to the output switch or
output storage capacitors. When the output boost voltage of the at
node PF+ rises above 405V, zener diodes D1103, D1102 and D1100
conduct a small current into the gate of SCR1101 latching SCR1101
on. Resistor R1100 provides holding current for SCR1101. Turning
SCR1101 provides gate current to SCR1100, resistors R1100 and R1101
limits the gate current and provides the hold current to SCR1100.
With gate current to SCR1100 the SCR is turned on providing a low
impedance path from nodes CP18V+ to BR-. This action removes the
regulated power to the main switch buffer and or PWM controllers
PFA (FIG. 23) or PWFM (FIG. 33) and or buffer AMP (FIG. 29) thus
turning off the main switch. The converter is held in an off state
until boost voltage PF+ through R1100 can not maintain the holding
current of SCR1101. Typically power must be removed from the system
to reset SCR1101. The minimum holding current of SCR1101 is
typically 5-10 ma. The action of OVP1 quickly limits the boost
output voltage to a safe level. This circuit should never operate
under normal AC line voltages. By changing zener voltages this
sub-circuit would also be suitable for use across the output
rectifier to protect the load from an over voltage condition.
Sub-circuit OVP1 gracefully shuts down the converter requiring
manual intervention to reset the fault.
[0208] FIG. 42B is the schematic of the isolated output over
voltage feed back network sub-circuit OVP2. Sub-circuit OVP2
consists of resistors of R970, R971, and R972, capacitor C970,
zener diode D970, SCR SCR970, Darlington transistor Q970 and
opto-isolator U970.
44 Table Element Value/part number D970 1N5261BOTCT U970 NEC2501
Q970 FZT705CT R970 160 k ohms R971 10 k ohms R972 22 k ohms C970
200 pf
[0209] The output of the converter at pin OUT+ is connected to R972
and to the cathode of zener diode D970. The anode of D970 is
connected to series resistor R970 then to base of Q970. Resistor
R970 sets the maximum base current to Q970. Resistor R971 is
connected between the anode of D970 and return node OUT- Anode of
light emitting diode U970 is connected to resistor R972 then to
OUT+. The cathode of U970 LED is connected to Q980 collector.
Emitter of Q980 is connected to return node OUT-. Zener diode D960
sets the maximum or trip voltage before transistor Q970 is biased
on providing current to U970 LED. Application of voltage greater
than the zener voltage of D970 injects a small base current into
Q970. Transistor Q970 turns on the internal LED of U970 placing
phototransistor in a conducting state and low impedance to pins OVC
and OVC. External push-pull driver sub-circuit PPG (FIG. 43) is
shut down immediately by bringing pin PPEN high stopping the output
stage. Sub-circuit OVP2 senses the output voltage and quickly feeds
back to the push-pull PFC. Where excessive boost voltage forces the
PFC to automatically reduce the boost voltage.
[0210] FIG. 42C is the schematic of the isolated output over
voltage crowbar network sub-circuit OVP3. Sub-circuit OVP3 consists
of resistors of R980, R981, R982, R983, R984 and R985, capacitors
C980, C981 and C982 zener diode D980, SCRs SCR980 and SCR981,
Darlington transistor Q980 and opto-isolator U980.
45 Table Element Value/part number D980 1N5261BOTCT SR980 S601E
(Teccor) U980 NEC2501 Q980 FZT705CT R980 160 k ohms R981 10 k ohms
R982 22 k ohms R983 51 k ohms R984 1200 ohms R985 510 ohms C980 200
pf C981 1200 pf C982 1200 pff
[0211] The converter output is sensed at pin OUT+ reference to pin
OUT-. Pin OUT+ is connected to resistor R982 and to the cathode of
zener diode D980. The anode of D980 is connected to series resistor
R980 then to base of Q980. Resistor R980 limits the base current to
Q980. Resistor R981 is connected between the anode of D980 and
return node OUT- to provide a diode leakage current path. Anode of
light emitting diode U980 is connected through resistor R982 then
to OUT+. The cathode of U980 LED is connected to Q980 collector.
Emitter of Q980 is connected to return node OUT-. Zener diode D960
sets the maximum or trip voltage before transistor Q980 is biased
on providing current to U980 LED. Application of voltage greater
than the zener voltage of D980 injects a small base current into
Q980.Emitter of opto-isolator U980 is connected to the gate of
SCR981 and through [R984.parallel.C982] to return node BR-.
Transistor Q980 turns on the internal LED of U980 placing
phototransistor in a conducting state and supplying gate current to
SRC SCR981 from the external 18-volt source connected to pin
CP18V+. Network [R984.parallel.C982] prevents false triggering of
SCR SCR981. The cathode of SCR SCR981 is connected to the gate of
SCR SCR980 and through [R985.parallel.C981] to return BR-. With SCR
SCR981 turned on gate current is provided to low voltage SCR
SCR980. High voltage boost output is connected to pin PF+ resistor
R983 supplies hold current to SCR SCR981 holding SCR SCR980 on. SCR
SCR980 is selected for low hold current and ability to block the
maximum boost voltage on PF+. SCR SRC980 anode is connected to pin
CP18V+. SCR SRC980 cathode is connected to return pin BR-. SCR980
clamps the low voltage supply CP (FIG. 26) or CPA (FIG. 27). With
the low supply held down the gate drive to the main switch is
disabled turning off the converter. With the main switch Q1 (FIG.
1,3,4) turned off holdup capacitor C17 charges to applied AC line
peak. With pin PF+ held near line peak SCRs SCR981 will hold SCR
SCR981 on until AC line power is removed to the converter.
Sub-circuit OVP3 senses the out of specification output voltage and
quickly stop the converter thereby protecting the load and
converter with out generating destructive currents like OVP (FIG.
42).
[0212] FIG. 43 Push-pull oscillator sub-circuit PPG FIG. 43 is the
push-pull oscillator sub-circuit of the invention. The current
implementation uses a Motorola MC33025 pulse width modulator IC to
generate the clock signals to drive the push-pull output stage.
Sub-circuit PPG consists of U14 a two-phase oscillator, resistors
R126, R130, R131, R132, R133, R134, R135, R136 and R137, capacitors
C143, C136, C139, C140, C141 and C142.
46 Table Element Value/part number U14 MC33025 R126 12 k ohms R130
10 ohms R131 10 ohms R132 47 k ohms R133 10 k ohms R134 100 k ohms
R135 15 k ohms R136 1.5 MEG ohms R137 15 k ohms C136 0.22 uf C139
0.22 uf C140 0.22 uf C141 0.01 uf C142 0.001 uf C143 .33 uf
[0213] The current implementation uses a Motorola MC33025 pulse
width modulator IC to generate the clock signals to drive the
push-pull stage. But, any non-overlapping two phase fixed frequency
generator could be used. Pin 1 of U14 is connected to [capacitor
C143.parallel.Resistor R132] then to pin 3. Resistor R134 connects
the internal 5.1-volt reference output of U14 pin 16 to pin 1.
Resistors R135 in series with R137 from 5.1-volt reference to
return node PPG0 form a voltage divider; the center is connected to
U14 pin 2 placing pin 2 at 2.55-volts. Resistor R126 is connected
from U14 pin 5 to return node PPG0. Resistor R133 is connected from
U14 pin 1 to return node PPG0. Timing capacitor C142 is connected
from U14 pins 6 and 7 to return node PPG0. Resistor R126 and
capacitor C142 set the operating frequency of the internal
oscillator. Timing resistor could be replaced with a JFET, MOSFET,
transistor, or similar switching device to provide variable
frequency operation. The drain of the transistor would be connected
to pin 5. The source would be connected to return node PPG0. The
variable frequency command voltage/current is applied between gate
and source. Capacitor C141 is connected from U14 pin 8 to return
node PPG0. Capacitor C136 is connected from U14 pin 16 to return
node PPG0. Capacitor C140 is connected from U14 pin 15 to return
node PPG0. Capacitor C139 is connected from U14 pin 13 to return
node PPG0. Resistor R136 is connected from U14 pin 9 to return node
PPG0. U14 pins 10 and 12 is connected to return node PPG0. External
power is connected to node/pin PPG+ to PWM (pulse width modulator)
IC U14 on pin 15 through resistor R130 connected to the 18-volt
control supply. Resistor R131 connected to pin 13 of U14 and PPG+
provides power to the totem-poll output stage. The power return
line is connected to node PPG0. IC U14 is designed to operate at a
constant frequency of approximately 20.-600 Khz with a fixed duty
cycle of 35-49.9%. Resistors R135, R137, R133 configure U14 to
operate at maximum pulse width. A two-phase non-over lapping square
wave is generated on pins 11 node PH2 and pin 14 node PH1 and
delivered to speed-up buffers AMP described in FIG. 29. The
two-phase generator is configured to prevent the issue of
overlapping drive signals that would null the core bias and present
excessive current to the switches. Sub-circuit PPG provides the
drive to the push-pull switches making efficient use of the NSME.
Although the present invention has been described with reference to
a preferred embodiment, numerous modifications and variations can
be made and still the result will come within the scope of the
invention. No limitation with respect to the specific embodiments
disclosed herein is intended or should be inferred.
* * * * *