U.S. patent application number 15/339811 was filed with the patent office on 2017-02-16 for power quality enhancement.
The applicant listed for this patent is Laurence P. Sadwick. Invention is credited to Laurence P. Sadwick.
Application Number | 20170047859 15/339811 |
Document ID | / |
Family ID | 50880236 |
Filed Date | 2017-02-16 |
United States Patent
Application |
20170047859 |
Kind Code |
A1 |
Sadwick; Laurence P. |
February 16, 2017 |
Power Quality Enhancement
Abstract
A power supply includes an alternating current input, a
rectifier operable to generate a rectified signal based on the
alternating current input, a voltage multiplier configured to
generate a multiplied voltage based on the alternating current
input, and an output configured to yield an electrical current
based on the rectified signal from the rectifier and on the
multiplied voltage from the voltage multiplier. Current is drawn
from the alternating current input only during a fraction of each
half-cycle of a waveform at the alternating current input.
Inventors: |
Sadwick; Laurence P.; (Salt
Lake City, UT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sadwick; Laurence P. |
Salt Lake City |
UT |
US |
|
|
Family ID: |
50880236 |
Appl. No.: |
15/339811 |
Filed: |
October 31, 2016 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
14104972 |
Dec 12, 2013 |
9516722 |
|
|
15339811 |
|
|
|
|
61736080 |
Dec 12, 2012 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
Y02B 70/10 20130101;
Y02B 70/123 20130101; H02J 7/00 20130101; H05B 41/28 20130101; H02M
7/06 20130101; H02M 1/4266 20130101; H05B 45/37 20200101; H02M 1/44
20130101; H05B 45/10 20200101; H02J 7/02 20130101; H02J 7/022
20130101; H02J 2207/20 20200101; H05B 47/00 20200101; H02M 7/103
20130101 |
International
Class: |
H02M 7/06 20060101
H02M007/06; H02M 1/44 20060101 H02M001/44; H02J 7/00 20060101
H02J007/00; H05B 33/08 20060101 H05B033/08 |
Claims
1. A power supply, comprising: an alternating current input; a
rectifier configured to generate a rectified signal based on the
alternating current input; a voltage multiplier configured to
generate a multiplied voltage based on the alternating current
input; and an output configured to yield an electrical current
based on the rectified signal from the rectifier and on the
multiplied voltage from the voltage multiplier, wherein current is
drawn from the alternating current input only during a fraction of
each half-cycle of a waveform at the alternating current input.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to U.S. patent
application Ser. No. 14/104,972 entitled "Power Quality
Enhancement", filed Dec. 12, 2013, which is incorporated herein by
reference for all purposes.
BACKGROUND
[0002] Electricity is typically generated and distributed in
alternating current (AC) form, wherein the voltage varies
sinusoidally between a positive and a negative value. However, many
electrical devices require a direct current (DC) supply of
electricity having a constant voltage level or constant current
level, or at least a supply that remains positive even if the level
is allowed to vary to some extent. In one type of commonly used
power supply for loads such as an LED, an incoming AC voltage is
connected to the load and current is drawn only during certain
portions of the sinusoidal waveform. For example, a fraction of
each half cycle of the waveform may be used by connecting the
incoming AC voltage to the load each time the incoming voltage
rises to a predetermined level or reaches a predetermined phase and
by disconnecting the incoming AC voltage from the load each time
the incoming voltage again falls to zero or capacitors that are
used in the power supply circuit may charge only near the peak of,
for example, the rectified AC input voltage. In this manner, a
positive but reduced voltage may be provided to the load. This type
of conversion scheme often results in a `peak` region, often being
a relatively narrow peak region, in the AC current drawn from the
AC source as a percentage of the AC cycle often occurring at the
peak/maximum of the AC voltage. This type of AC current waveform
and profile is often highly undesirable due to the poor power
factor and high total harmonic distortion (THD) generated by and
associated with such a current waveform and profile.
SUMMARY
[0003] The driver disclosed herein provides power for any type of
load, including lights such as light emitting diodes (LEDs) of any
type including, for example, organic light emitting diodes (OLEDs).
A voltage increasing circuit is active during a portion of an
output waveform to more closely approximate a desired waveform. In
some embodiments this may be used to decrease total harmonic
distortion.
[0004] This summary provides only a general outline of some
particular embodiments. Many other objects, features, advantages
and other embodiments will become more fully apparent from the
following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] A further understanding of the various embodiments of the
present invention may be realized by reference to the figures which
are described in remaining portions of the specification. In the
figures, like reference numerals may be used throughout several
drawings to refer to similar components.
[0006] FIG. 1 depicts a schematic diagram of a simple AC to DC
power converter;
[0007] FIG. 2 depicts a schematic diagram of a simple AC to DC to
power converter modified with a voltage doubler in accordance with
some embodiments of the invention;
[0008] FIGS. 3A, 3B, 3C are block diagrams of a simple AC to DC
power converter modified with a voltage doubler and other types of
DC to DC converters, LED drivers, FL and CFL ballasts, lighting
power supply, power supply, battery charger, etc. in accordance
with some embodiments of the invention;
[0009] FIG. 4 depicts a schematic of one example circuit
implementation with the optional diodes D47 and D50 that can be
applied to, for example, the circuits of FIGS. 1, 6 and 8 in
accordance with some embodiments of the invention;
[0010] FIG. 5 depicts a schematic of one example circuit
implementation without the optional diodes that can be applied to,
for example, the circuits of FIGS. 1, 6 and 8 in accordance with
some embodiments of the invention;
[0011] FIG. 6 depicts a block diagram of a dimmable LED driver with
multiple power sources, including a low side tag-along inductor for
which FIG. 4 or 5 can be applied to the present invention;
[0012] FIG. 7 depicts a plot of AC input current of a dimmable or,
in a similar non-dimmable, LED driver with a relatively high LED
forward voltage supplied with a 60 Hz AC input voltage without the
embodiments of the present invention;
[0013] FIG. 8 depicts a schematic of a dimmable LED driver with
multiple power paths and power sources, including a tag-along
inductor, in accordance with some embodiments of the present
invention for which FIG. 4 or 5 can be applied of the present
invention;
[0014] FIG. 9 shows a measurement of a dimming or non-dimming
driver similar to the block diagram and schematic of FIGS. 6 and 8,
respectively, without the present invention incorporated;
[0015] FIG. 10 shows a measurement of a dimming or non-dimming
driver similar to the block diagram and schematic of FIGS. 6 and 8,
respectively, with the present invention; and
[0016] FIG. 11 shows an expanded view measurement of a dimming or
non-dimming driver similar to the block diagram and schematic of
FIGS. 6 and 8, respectively, with an embodiment of the present
invention incorporated.
DESCRIPTION
[0017] The power quality enhancement system disclosed herein
provides enhanced power quality from multiple paths, providing
power from sources such as AC line voltage sources for use in
powering any electronic circuits or devices especially those with
low power quality such as low power factor or high THD. The power
output in some embodiments from the multiple path system is a
rectified waveform that can optionally be filtered to yield a
direct current output. The power sources are not limited to any
particular source. In some embodiments, the power source can have a
fixed or universal range of AC input voltages including 47 to 63 Hz
(i.e., 50 and/or 60 Hz) and 400 Hz, etc. The multiple power paths
may be used to provide power to internal circuits in a dimmable LED
driver, such as the various dimmable LED drivers and their
variations disclosed in U.S. patent application Ser. No.
12/422,258, filed Apr. 11, 2009 for a "Dimmable Power Supply",
which is incorporated herein by reference for all purposes. In some
embodiments, power may be provided to charge one or more batteries
or other energy storage devices. By a judicious choice of
components, power factor and THD enhancements can be tailored to
meet the specifics of the applications.
[0018] Power may be obtained from sources such as but not limited
to an AC or DC line, a tag-along inductor that inductively couples
to another inductor in an electrical circuit, a battery, solar
cells, photovoltaics, vibrational, heat, mechanical, sources,
etc.
[0019] When used to power a light such as an LED of any type, the
driver draws an alternating current (AC) current from an AC source
to provide a direct current (DC) supply of electricity with a
constant voltage level or constant current level, or at least a
supply that remains positive even if the level is allowed to vary
to some extent. For example, light emitting diodes (LEDs) and
similar devices such as organic light emitting diodes (OLEDs) are
being increasingly considered for use as light sources in
residential, commercial and municipal applications. However, in
general, unlike incandescent light sources, LEDs and OLEDs cannot
be powered directly from an AC power supply unless, for example,
the LEDs are configured in some back to back formation. Electrical
current flows through an individual LED easily in only one
direction, and if a negative voltage which exceeds the reverse
breakdown voltage of the LED is applied, the LED can be damaged or
destroyed. Furthermore, the standard, nominal residential voltage
level is typically something like 120 V or 240 V, both of which are
often higher than may be desired for a high efficiency LED light.
Some conversion of the available power may therefore be necessary
or highly desired with loads such as an LED light.
[0020] In one type of commonly used power supply for loads such as
an LED, an incoming AC voltage is connected to the load and current
is drawn only during certain portions of the sinusoidal waveform.
For example, a fraction of each half cycle of the waveform may be
used by connecting the incoming AC voltage to the load each time
the incoming voltage rises to a predetermined level or reaches a
predetermined phase and by disconnecting the incoming AC voltage
from the load each time the incoming voltage again falls to zero or
capacitors that are used in the power supply circuit may charge
only near the peak of, for example, the rectified AC input voltage.
In this manner, a positive but reduced voltage may be provided to
the load. This type of conversion scheme often results in a `peak`
region, often being a relatively narrow peak region, in the AC
current drawn from the AC source as a percentage of the AC cycle
often occurring at the peak/maximum of the AC voltage.
[0021] An example of a relatively simple circuit 100 with such an
AC current waveform is shown in FIG. 1. A diode bridge or rectifier
including diodes 102, 104, 106, 108 rectifies current from an AC
input 110, powering a load 112, with optional filtering by
capacitor 114. FIG. 7 shows the associated AC current waveform for
a typical simple circuit as depicted in FIG. 1. This type of AC
current waveform and profile is often highly undesirable due to the
poor power factor and high total harmonic distortion (THD)
generated by and associated with such a current waveform and
profile. In many cases such a current waveform/profile is no longer
considered acceptable by agency standards and regulations and
products including new products must be made to conform to a
certain level of power quality including a minimum allowable power
factor and a maximum allowable THD. In addition, many power
supplies, lighting drivers including, but not limited to, LED
drivers, fluorescent lamp (FL) and compact fluorescent lamp (CFL)
ballasts, battery chargers, etc. are required to adhere and meet
these standards and regulations. For lighting applications, this
type of conversion scheme in which AC is converted to DC is often
controlled so that a constant current is provided to the load even
if the incoming AC voltage varies. However, if this type of power
supply, and, often, other types of power supplies, with current
control is used in an LED light fixture or lamp, the power factor
and/or total harmonic distortion (THD) may be adversely affected
and impacted especially for a relatively high LED forward voltage.
In addition, a conventional dimmer is often ineffective or impaired
in use and operation with such a poor power quality AC to DC
converter. For example, for many LED power supplies, the power
supply will attempt to maintain the constant current through the
LED despite a drop in the incoming voltage by increasing the
on-time during each cycle of the incoming AC wave.
[0022] FIG. 2 depicts a schematic diagram of a simple AC to DC
power converter 200 modified with a voltage doubler in accordance
with some embodiments of the invention. The term "voltage doubler"
is used herein to refer to a circuit that draws current from an
input to an output, such as the voltage doubler consisting of
capacitors 220, 222 and diodes 224, 226. The term "voltage doubler"
does not imply herein that an output voltage is exactly twice the
input voltage including over the complete AC cycle. In some
embodiments of the present invention, the "voltage doubling" may be
significantly different (e.g., less) than double the input
voltage.
[0023] The power converter powers a load (e.g., capacitor 214 and
resistor 212) using a voltage rectifier (e.g., diodes 202, 204,
206, 208) from power source 210. If the output voltage or current
is regulated or controlled by switching the power converter to the
load at peaks in the input waveform, then portions of the input
waveform as shown in FIGS. 7 and 9 are omitted, such as the rising
and falling edges, also referred to herein as the slopes, and the
input current is no longer a sinusoidal waveform. A voltage doubler
such as that including capacitors 220, 222 and diodes 224, 226 acts
to fill the missing slopes somewhat to more nearly approximate the
desired sinusoidal waveform, producing input current waveforms such
as those shown in FIGS. 10 and 11. Diodes 230 and 232 are optional
and can be used to block the lower of the respective full wave
diode rectifier and voltage doubler voltages. Although passive
and/or active methods can be used in the present invention, by a
judicious and careful choice of component values, the circuits
depicted in FIGS. 2, 4 and 5 can be designed and implemented such
that the circuit automatically passively switches from the voltage
doubler supplied path power to the diode bridge supplied path power
such that the overall AC current waveform is increased to cover
more of the AC cycle resulting in either or both an increased,
larger power factor and/or a decreased, lower THD.
[0024] If a control system is used to regulate the output voltage
and/or current by switching the connection between the power
converter and the load, the control system can monitor the output
voltage and/or current and adjust the switching to take into
account the additional current from the voltage doubler. In this
way, the desired output voltage and/or current levels are
maintained, while the input current waveform more nearly
approximates a sinusoidal waveform. In some embodiments, this may
be applied to reduce total harmonic distortion.
[0025] The capacitance of capacitors 220, 222 is selected in some
embodiments to be small enough that the voltage doubler is active
mainly at low currents to fill in the missing slopes of the input
current sinusoidal waveform, but to be substantially inactive at
peak current levels. In other embodiments, the missing slopes in
the input current sinusoidal waveform may be filled in by a current
source that is switched on to fill in the missing slopes and
switched off at peak current levels.
[0026] FIGS. 3A, 3B, 3C depict various block diagrams for some of
the embodiments of the present invention. As shown in FIG. 3A, the
AC input 302 can be provided to a rectifier 304 and voltage
multiplier 306, with the resulting voltage(s) provided to an
optional combiner/selector 312. The combiner/selector 312 is
operable to select either the voltage from the rectifier 304 or
from the voltage multiplier 306 to provide to a driver circuit
and/or load 316. In some embodiments, the combiner/selector 312 is
operable to combine the voltages from the rectifier 304 and the
voltage multiplier 306 to provide to the driver circuit and/or load
316, for example switching between the two based on the voltage
level from the rectifier 304 to provide a multiplied or increased
voltage level when the voltage from the rectifier 304 is lower than
desired. As shown in FIG. 3B, in some embodiments the power from
the combiner/selector 312 is provided to a DC to DC converter 318
to regulate voltage and/or current provided to a load 322 at a
desired fixed or varying level. As shown in FIG. 3C, in some
embodiments the power from the combiner/selector 312 is provided to
one or more other power related circuits 324, such as a driver for
lighting devices or other loads, such as, but not limited to, an
LED driver, a ballast or other power supply for a fluorescent lamp,
compact fluorescent lamp (CFL), cold-cathode fluorescent lamps
(CCFLs), neon lamps or other lighting device, or to a power supply,
battery charger, etc. Such power related circuits 324 can be used
to power any suitable load or loads 326.
[0027] The present invention can be designed and implemented such
that the voltage multiplier, in the case shown and illustrated in
FIGS. 2, 4, and 5, a voltage doubler, is only active over a portion
of the AC cycle with such portion being before the peak in the AC
voltage thus aiding in filling in the AC input current input
waveform. As the AC current can be represented as a Fourier series
of sine waves, the goal is to reduce the amplitudes of the
harmonics associated with the Fourier series. This can be
accomplished, for example, by designing the voltage multiplier such
that the current from the voltage multiplier merges with the
current from, for example, the high forward voltage LED driver.
Although the present invention is applicable to many types of power
supplies, drivers, ballasts, battery chargers, etc. including ones
using, for example, boost-buck, buck-boost, boost, buck, isolated,
non-isolated, flyback, SEPIC, Cuk, forward-converters, etc., the
present invention is especially applicable to buck converters and
related circuits, approaches, and topologies, etc.
[0028] FIGS. 4 and 5 depict examples of the present invention using
a voltage multiplier--in this case a voltage doubler designed to
support voltage doubling over a defined portion of the AC cycle.
Turning to FIG. 4, an AC to DC power converter 400 includes a
voltage doubler in accordance with some embodiments of the
invention. A voltage doubler consisting of capacitors 420, 422 and
diodes 424, 426 draws power from AC input 410 and adds or combines
the output with the output of rectifier 428 over a portion of the
AC cycle at high voltage DC (HVDC) output 434. Diodes 430 and 432
block the lower of the respective full wave diode rectifier and
voltage doubler voltages, passing the higher of the two voltages to
output 434 at any given portion of the AC cycle. The component
values are selected in some embodiments so that the circuit
automatically passively switches from the voltage doubler supplied
path power to the diode bridge supplied path power such that the
overall AC current waveform is increased to cover more of the AC
cycle resulting in either or both an increased, larger power factor
and/or a decreased, lower THD. Turning to FIG. 5, in some
embodiments the blocking diodes are omitted in AC to DC power
converter 500. A voltage doubler consisting of capacitors 520, 522
and diodes 524, 526 draws power from AC input 510 and adds or
combines the output with the output of rectifier 528 over a portion
of the AC cycle at high voltage DC (HVDC) output 534. The component
values are selected in some embodiments so that the circuit
automatically passively switches from the voltage doubler supplied
path power to the diode bridge supplied path power such that the
overall AC current waveform is increased to cover more of the AC
cycle resulting in either or both an increased, larger power factor
and/or a decreased, lower THD.
[0029] Although two power paths (i.e., the full wave diode bridge
and the voltage doubler) are illustrated in the example drawings
contained herein, in general, N power paths connected to a source
such as an AC voltage may be used where N is greater than 1 (i.e.,
N=2, 3, 4, etc.). These N paths can be voltage doublers, triplers,
multipliers, etc. including multiple (i.e., more than one each)
voltage doublers or triplers, quadruplers, multipliers, etc. with
different configurations or components, component values, etc.
[0030] Turning to FIG. 6, an embodiment of a dimmable LED driver
600 is shown in which rectifier 614 comprises a circuit such as
those depicted in FIGS. 4 and 5, powering a load 610 as well as
internal devices and circuits such as a variable pulse generator
606, while allowing multiple power paths for power quality
enhancement. The term "power source" is used herein to refer to the
origin of a voltage or current, in contrast to a circuit such as a
voltage regulator that may scale, limit or otherwise process the
voltage and/or current levels obtained from the power source.
Examples of power sources include but are not limited to AC and/or
DC lines, tag-along inductors, transformers, batteries, energy
harvesting sources such as solar, photovoltaic, mechanical,
vibrations, wireless, etc.
[0031] Some embodiments of the present invention can use
synchronous transistors including field effect transistors (FETs)
(e.g., MOSFETs, JFETs, Gallium Nitride-based FETs (GaNFETs),
Silicon Carbide FETs (SiCFETs), diamond FETs, etc.) and/or bipolar
junction transistors (BJTs) including Darlington transistors and
pairs in place of diode(s) including for the diode bridges and
multiplier (i.e., doubler, tripler, quadrupler, etc.) diodes and
others, etc.
[0032] The dimmable LED driver 600 powers and controls a load 610
such as one or more LED lights, from a power source such as an AC
input 612. A rectifier 614 may be used to convert the AC input 612
and provide a DC signal to a DC rail 616. A switch 620 is
controlled by the variable pulse generator 606, blocking or
allowing current to flow from the DC rail 616 to a return rail 622
through the switch 620. As current flows through the switch 620, it
also flows through a series inductor 624, storing energy in the
inductor 624. When the switch 620 is turned off by the variable
pulse generator 606, the inductor 624 releases energy, which
circulates through a diode 626 and through the load 610. As will be
understood by those of ordinary skill in the art, other components
may be included such as capacitor 630 illustrated in parallel with
load 610, and other devices to facilitate the desired functionality
in the dimmable LED driver 600. In other embodiments, the load may
consist of one or more capacitors in parallel with the LED(s), etc.
In other embodiments and applications, the load may consist of
things other than LEDs, OLEDs, etc., such as, but not limited to
resistive, capacitive, inductive, reactive, etc. and/or
combinations of the these, etc.
[0033] The first power source 602 draws power from the DC rail 616,
regulating or dividing or otherwise setting the voltage level at an
appropriate level, for example, for the variable pulse generator
606. The second power source 604 draws power from an inductor 632
adjacent the main inductor 624, inductively coupling power flowing
through the main inductor 624 into the power source 604.
[0034] The inductor 632 may be located adjacent to the main
inductor 624 in any suitable manner, for example by winding the
inductor 632 around or along with the inductor 624. The inductors
624 and 632 may share a core 634, and the relative placement of the
windings of inductors 624 and 632 and the core 634 is not limited
to any particular arrangement.
[0035] The inductor 632 may be wound with an opposite polarity.
When wound with one polarity, when the voltage and current in the
inductor 624 is limited and, for example, the LED power
supply/driver is either in constant current or voltage mode, the
voltage from the power source 604 is constant. When wound with the
other polarity, the inductor 632 and power source 604 are in the
forward mode, and when the input voltage at DC rail 616 goes up,
the voltage from the power source 604 goes up. Additional power may
be supplied from other sources such as snubbers and clamps,
including non-dissipative snubbers and clamps, and other types of
energy storage devices and components including but not limited to
inductors or capacitors of any type and combinations of these. As
mentioned above, batteries, solar cells, photovoltaics,
vibrational, mechanical, heat, thermal, wired, wireless, RF, etc.
sources of energy may also be used with the present invention.
[0036] As disclosed above, the multiple power paths are not limited
to use in any particular application. In other example embodiments
of dimmable LED drivers, a controller measures the load current
through a sense resistor, and controls a variable pulse generator
based in part upon the load current. In some versions a level
shifter or isolator may be included and may be used to feed the
signal from the sense resistor to the controller or a sense
transformer or other such device may be used as well as transistors
to convey information about the current through the load. Other
embodiments of the present invention may use other methods to sense
current (and/or voltage and/or power) including, but not limited
to, current transformers, voltages across or through components,
turns of wire, magnetic sensors, etc. As mentioned above, although
not required for the present invention, some applications and/or
embodiments may use level shifters, optocouplers, optoisolators,
transistors, etc. as part of the feedback. The present invention
may or may not use such level shifting and is, in no way or form,
limited to the use or non-use of level shifting, etc. The variable
pulse generator may further be controlled by the current level
through the switch as measured by another sense resistor 608 or
other means. A snubber circuit may be included to suppress
transient voltages and improve noise performance, etc. One or more
clamp circuits may also be used. As mentioned above, the energy and
associated power with the snubber(s) and/or clamp(s) may be used as
part of the multiple power sources. An EMI filter may be included
to reduce electromagnetic interference which, in some embodiments,
may also be used for energy recovery, and a fuse 612 may be
included to protect against short circuits, etc. In some
configurations it may be possible to use the EMI filter as a power
source.
[0037] FIG. 7 shows an example of the AC current for a driver of
the type depicted in FIG. 6 without the present invention. Such a
driver may have a THD higher than desired or above the allowed
agency and regulatory limits and specifications.
[0038] An example embodiment of a dimmable LED driver 800 with
multiple power sources 802 and 804 is illustrated in FIG. 8, with a
high voltage DC power input 810 supplied from a power circuit such
as those shown in FIGS. 4 and/or 5. For example, the example
implementations depicted in FIGS. 4 and 5 may be connected to the
example dimmable driver illustrated in FIG. 8 at the HVDC 810 and
VSS (GND) 820 points, respectively.
[0039] The dimmable LED driver 800 powers and controls a load such
as one or more LED lights 806, from a power source such as a DC
rail 810. A transistor 812 is controlled by a variable pulse
generator 814 or other control circuit through a FET control signal
816, blocking or allowing current to flow from the DC rail 810 to a
ground 820 through the transistor 812. Again, in this example
embodiment, as current flows through the transistor 812, it also
flows through a series inductor 822, storing energy in the inductor
822. When the transistor 812 is turned off by the variable pulse
generator 814, the inductor 822 releases energy, which then
circulates through a diode 824 or other secondary path and through
the LED 806.
[0040] Other components may be included, such as a snubber circuit
826. One or more optional capacitors may be connected in parallel
with the load as shown. Again, these other components may be also
used as a power source.
[0041] In the first power source 802, current flows through a
transistor 830 and resistor 832 to a VDD voltage node 834. A Zener
diode 836 limits and sets the voltage level that may be supplied by
the power source 802.
[0042] In the second power source 804, current flows from an
inductor 840 wound with inductor 822 to the VDD voltage node 834,
with the voltage supplied by the power source 804 set and limited
by a Zener diode 842 and voltage regulating transistor 844.
Notably, in embodiments where regulation is not needed, the voltage
regulating transistor 844 and associated components are not
included, and the VDD voltage node 834 is driven directly from
inductor 840 through diode 852. Similar changes may be made in
power source 802.
[0043] The selection of one or both power sources 802 or 804 to
supply VDD voltage node 834 is set by diodes 850 and 852. If the
voltage from power source 802 is greater than that from power
source 804, the diode 852 in power source 804 will be reverse
biased and power source 804 will not supply current to VDD voltage
node 834. If the voltage from power source 804 is greater than that
from power source 802, the diode 850 in power source 802 will be
reverse biased and the power source 802 will not supply current to
VDD voltage node 834. Although the selection of power sources and
power paths in the above example embodiments involved diodes, the
present invention is in no way limited to the use of diodes only;
the selection can be made, for example, by diodes, switches,
transistors, other types of semiconductor and active and passive
components, digital and/or analog methods, techniques, approaches,
etc., by monitoring and selecting certain voltage values, etc.
These examples are meant to be illustrative and in no way or form
limiting for the present invention.
[0044] FIG. 9 shows the AC input current waveform for a driver
representative of the drivers shown in FIGS. 6 and 8 that have
relatively high LED forward voltages without the present invention.
FIGS. 10 and 11 show the associated AC input current and input
voltage waveforms along with the current through the voltage
doubler for a driver representative of the drivers shown in FIGS. 6
and 8. In FIG. 10, trace 1002 is the AC input sine wave voltage.
The voltage at point 1004 of the output waveform is substantially
provided by the input current path through the diode rectifier
bridge, while the voltages at points 1006 and 1008 are
substantially provided by the input current path through the
voltage doubler. In FIG. 11, a portion of the AC input sine wave is
shown in trace 1102, the input current through the voltage doubler
is shown in trace 1104, and the total AC input current is shown in
trace 1106. The associated power factor and THD without the present
invention are 0.91 and 44%, respectively and 0.93 and 27%,
respectively with the present invention in the figures shown; other
values of power factor and THD, including higher power factor and
lower THD may be obtained with the present invention and the
present invention is not restricted nor limited in any way or form
to the numerical values listed for power factor and THD herein. The
present invention can also include passive and active components
and circuits that assist, support, facilitate, etc. the operation
and function of the present invention. Such components can include
passive components such as resistors, capacitors, inductors,
filters, transformers, diodes, other magnetics, combinations of
these, etc. and active components such as switches, transistors,
integrated circuits, including ASICs, microcontrollers,
microprocessors, digital signal processors (DSPs), field
programmable gate arrays (FPGAs), complex logic devices (CLDS),
programmable logic, digital and or analog circuits, and
combinations of these, etc. and as also discussed below.
[0045] The present invention can be used in, among other things,
power supplies, drivers, ballasts, etc. with or needing high power
factor (PF) and/or lower THD circuits with or without dimming
including triac, forward and reverse dimmers, 0 to 10 V dimming,
powerline dimming, wireless (including but not limited to WiFi,
WiMax, ZigBee, IEEE 801, ISM, GSM, Bluetooth, etc.--essentially any
wireless signal, frequency, protocol, etc. including radio
frequency and optical (i.e., infrared)) and other wired dimming,
DALI dimming, PWM dimming, DMX, etc., as well as any other dimming
and control protocol, interface, standard, circuit, arrangement,
hardware, etc.
[0046] A dimmable LED driver with multiple power sources may also
be used in embodiments having a load below the main inductor. As
before, a capacitor may be connected in parallel with the load. The
dimmable LED driver powers the load from an alternating current
(AC) input. A feedback loop based on the current through, for
example, a switch causes, as an example but in no way limiting or
limited to, a variable pulse generator to control the switch to
adjust the current through the switch and, therefore, through the
load. The AC input is rectified in a rectifier such as a diode
bridge and may be conditioned using a capacitor. An electromagnetic
interference (EMI) filter may be connected to the AC input to
reduce interference, and a fuse may be used to protect the dimmable
LED power supply and wiring from excessive current due to short
circuits or other fault conditions. In some embodiments, a short
circuit protection may be employed in addition to fuse protection,
etc.
[0047] Current to the load can be regulated or controlled by a
switch such as a transistor or other switch, under the control of a
variable pulse generator. A sense resistor is placed in series with
the switch or in any other suitable location to detect the current
through the switch or any other desired current, for use in
controlling the switch. The main inductor is connected in series
with the switch, and the load and a parallel capacitor are also
connected in series with the switch and the main inductor. A diode
is connected between the system ground and a local ground. When the
switch is turned on, current flows from the positive rail through
the switch and through the load and energy is stored in the main
inductor. When the switch is turned off, energy stored in the main
inductor is released through the load, with the diode providing a
return path for the current through the load and back through the
sense resistor and the main inductor.
[0048] The example embodiments disclosed herein illustrate certain
features of the present invention and not limiting in any way, form
or function of present invention. Note that linear or switching
voltage or current regulators or any combination can be used in the
present invention and other elements/components can be used in
place of the diodes, etc.
[0049] The present invention is, likewise, not limited in materials
choices including semiconductor materials such as, but not limited
to, silicon (Si), silicon carbide (SiC), silicon on insulator
(SOI), other silicon combination and alloys such as silicon
germanium (SiGe), etc., diamond, graphene, gallium nitride (GaN)
and GaN-based materials, gallium arsenide (GaAs) and GaAs-based
materials, etc. The present invention can include any type of
switching elements including, but not limited to, field effect
transistors (FETs) such as metal oxide semiconductor field effect
transistors (MOSFETs) including either p-channel or n-channel
MOSFETs, junction field effect transistors (JFETs), metal emitter
semiconductor field effect transistors, etc. again, either
p-channel or n-channel or both, bipolar junction transistors
(BJTs), either p-channel or n-channel or both, heterojunction
bipolar transistors (IBTs), high electron mobility transistors
(HEMTs), unijunction transistors, modulation doped field effect
transistors (MODFETs), Darlington transistors, GaN-based (GANFET),
SiC-based (SiCFET) etc., again, in general, n-channel or p-channel
or both, vacuum tubes including diodes, triodes, tetrodes,
pentodes, etc. and any other type of switch, etc. The present
invention can, for example, be used with any type of power supply
configuration and topology, including but not limited to,
continuous conduction mode (CCM), critical conduction mode (CRM),
discontinuous conduction mode (DCM), resonant modes, etc., of
operation with any type of circuit topology including but not
limited to buck, boost, buck-boost, boost-buck, cuk, etc., forward
converters including, but not limited to, voltage mode and current
mode, push-pull, etc., SEPIC, flyback, isolated or non-isolated
power supplies, drivers, ballasts, chargers, etc. The present
invention applies to all types of power supplies and sources and
the respective power supply(ies) can be of a constant frequency,
variable frequency, constant on time, constant off time, variable
on time, variable off time, constant period, variable period, etc.
Other forms of sources of power including thermal, optical, solar,
radiated, mechanical energy, vibrational energy, thermionic, etc.
are also included under the present invention. The present
invention may be implemented in various and numerous forms and
types including those involving integrated circuits (ICs) and
discrete components and/or both. The present invention may be
incorporated, in part or whole, into an IC, etc.
[0050] The present invention supports all standards and conventions
for 0 to 10 V dimming or other dimming techniques. In addition the
present invention can support, for example, overcurrent,
overvoltage, short circuit, and over-temperature protection.
[0051] Other embodiments can use other types of comparators and
comparator configurations, other op amp configurations and
circuits, including but not limited to error amplifiers, summing
amplifiers, log amplifiers, integrating amplifiers, averaging
amplifiers, differentiators and differentiating amplifiers, etc.
and/or other digital and analog circuits, microcontrollers,
microprocessors, complex logic devices, field programmable gate
arrays, etc.
[0052] The dimmer for dimmable drivers may use and be configured in
continuous conduction mode (CCM), critical conduction mode (CRM),
discontinuous conduction mode (DCM), resonant conduction modes,
etc., with any type of circuit topology including but not limited
to buck, boost, buck-boost, boost-buck, cuk, SEPIC, flyback,
forward-converters, etc. The present invention works with both
isolated and non-isolated designs including, but not limited to,
buck, boost-buck, buck-boost, boost, flyback and
forward-converters. The present invention itself may also be
non-isolated or isolated, for example using a tag-along inductor or
transformer winding or other isolating techniques, including, but
not limited to, transformers including signal, gate, isolation,
etc. transformers, optoisolators, optocouplers, etc.
[0053] The present invention includes other implementations that
contain various other control circuits including, but not limited
to, linear, square, square-root, power-law, sine, cosine, other
trigonometric functions, logarithmic, exponential, cubic, cube
root, hyperbolic, etc. in addition to error, difference, summing,
integrating, differentiators, etc. type of op amps. In addition,
logic, including digital and Boolean logic such as AND, NOT
(inverter), OR, Exclusive OR gates, etc., complex logic devices
(CLDs), digital signal processors (DSPs), field programmable gate
arrays (FPGAs), microcontrollers, microprocessors, application
specific integrated circuits (ASICs), etc. can also be used either
alone or in combinations including analog and digital combinations
for the present invention. The present invention can be
incorporated into an integrated circuit, be an integrated circuit,
etc.
[0054] The present invention can also incorporate at an appropriate
location or locations one or more thermistors (i.e., either of a
negative temperature coefficient [NTC] or a positive temperature
coefficient [PTC]) to provide temperature-based load current
limiting.
[0055] When the temperature rises at the selected monitoring
point(s), the phase dimming of the present invention can be
designed and implemented to drop, for example, by a factor of, for
example, two. The output power, no matter where the circuit was
originally in the dimming cycle, will also drop/decrease by a some
factor. Values other than a factor of two (i.e., 50%) can also be
used and are easily implemented in the present invention by, for
example, changing components of the example circuits described here
for the present invention. As an example, a resistor change would
allow and result in a different phase/power decrease than a factor
of two. The present invention can be made to have a rather instant
more digital-like decrease in output power or a more gradual
analog-like decrease, including, for example, a linear decrease in
output phase or power once, for example, the temperature or other
stimulus/signal (s) trigger/activate this thermal or other signal
control.
[0056] In other embodiments, other temperature sensors may be used
or connected to the circuit in other locations. The present
invention also supports external dimming by, for example, an
external analog and/or digital signal input. One or more of the
embodiments discussed above may be used in practice either combined
or separately including having and supporting both 0 to 10 V and
digital dimming. The present invention can also have very high
power factor. The present invention can also be used to support
dimming of a number of circuits, drivers, etc. including in
parallel configurations. For example, more than one driver can be
put together, grouped together with the present invention.
Groupings can be done such that, for example, half of the dimmers
are forward dimmers and half of the dimmers are reverse dimmers.
Again, the present invention allows easy selection between forward
and reverse dimming that can be performed manually, automatically,
dynamically, algorithmically, can employ smart and intelligent
dimming decisions, artificial intelligence, remote control, remote
dimming, etc.
[0057] The present invention may provide thermal control or other
types of control to, for example, a dimming LED driver. For
example, the circuit of FIGS. 6 and 8 or variations thereof may
also be adapted to provide overvoltage or overcurrent protection,
short circuit protection for, for example, a dimming LED driver, or
to override and cut the phase and power to the dimming LED
driver(s) based on any type of internal and/or external signal(s)
including arbitrary external signal(s) and/or stimulus. The present
invention can also include circuit breakers including solid state
circuit breakers and other devices, circuits, systems, etc. That
limit or trip in the event of an overload condition/situation. The
present invention can also include, for example analog or digital
controls including but not limited to wired (i.e., 0 to 10 V, RS
232, RS485, IEEE standards, SPI, I2C, USE, other serial and
parallel standards and interfaces, etc.), wireless, powerline, etc.
and can be implemented in any part of the circuit for the present
invention. The present invention can be used with a buck, a
buck-boost, a boost-buck and/or a boost, flyback, or
forward-converter design etc., topology, implementation, etc.
[0058] Other embodiments can use comparators, other op amp
configurations and circuits, including but not limited to error
amplifiers, summing amplifiers, log amplifiers, integrating
amplifiers, averaging amplifiers, differentiators and
differentiating amplifiers, etc. and/or other digital and analog
circuits, microcontrollers, microprocessors, complex logic devices,
field programmable gate arrays, etc.
[0059] The present invention includes implementations that contain
various other control circuits including, but not limited to,
linear, square, square-root, power-law, sine, cosine, other
trigonometric functions, logarithmic, exponential, cubic, cube
root, hyperbolic, etc. in addition to error, difference, summing,
integrating, differentiators, etc. type of op amps. In addition,
logic, including digital and Boolean logic such as AND, NOT
(inverter), OR, Exclusive OR gates, etc., complex logic devices
(CLDs), field programmable gate arrays (FPGAs), digital signal
processors (DSPs), microcontrollers, microprocessors, application
specific integrated circuits (ASICs), etc. can also be used either
alone or in combinations including analog and digital combinations
for the present invention. The present invention can be
incorporated into an integrated circuit, be an integrated circuit,
etc.
[0060] In conclusion, the present invention provides novel
apparatuses and methods for supplying circuits from multiple power
sources in dimmable LED drivers and in other applications. While
detailed descriptions of one or more embodiments of the invention
have been given above, various alternatives, modifications, and
equivalents will be apparent to those skilled in the art without
varying from the spirit of the invention. Therefore, the above
description should not be taken as limiting the scope of the
invention, which is defined by the appended claims.
* * * * *