U.S. patent application number 09/811680 was filed with the patent office on 2002-05-30 for dc to dc converter for operating in selectable voltage modes.
Invention is credited to Gu, Yilei, Huang, Guisong, Zhang, Alpha J..
Application Number | 20020064057 09/811680 |
Document ID | / |
Family ID | 21662151 |
Filed Date | 2002-05-30 |
United States Patent
Application |
20020064057 |
Kind Code |
A1 |
Zhang, Alpha J. ; et
al. |
May 30, 2002 |
DC TO DC CONVERTER FOR OPERATING IN SELECTABLE VOLTAGE MODES
Abstract
An integral DC to DC converter for converting at least one input
DC voltage into at least one output DC voltage is provided. The
integral DC to DC converter includes a first input capacitor and a
second input capacitor for providing the at least one input DC
voltage, a DC to AC circuit, a transformer, a rectifying circuit, a
filtering capacitor, two input DC voltage switching elements and an
output voltage switching element. The integral DC to DC converter
is implemented by switching the switching elements.
Inventors: |
Zhang, Alpha J.; (Neihu
Taipei, TW) ; Huang, Guisong; (Neihu Taipei, TW)
; Gu, Yilei; (Neihu Taipei, TW) |
Correspondence
Address: |
VOLPE AND KOENIG, P.C.
SUITE 400, ONE PENN CENTER
1617 JOHN F. KENNEDY BOULEVARD
PHILADELPHIA
PA
19103
US
|
Family ID: |
21662151 |
Appl. No.: |
09/811680 |
Filed: |
March 19, 2001 |
Current U.S.
Class: |
363/17 |
Current CPC
Class: |
H02M 3/33569 20130101;
H02M 1/10 20130101 |
Class at
Publication: |
363/17 |
International
Class: |
H02M 003/335 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 30, 2000 |
TW |
89125525 |
Claims
What is claimed is:
1. An integral DC to DC converter for converting at least one input
DC voltage into an output DC voltage, comprising: a first input
capacitor and a second input capacitor for providing said at least
one input DC voltage; a DC to AC circuit connected with said first
input capacitor and said second input capacitor for converting said
input DC voltage to a high frequency first AC voltage wherein said
DC to AC circuit comprises four full-bridge switching devices; a
transformer for converting said first AC voltage into a second AC
voltage wherein the primary winding of said transformer is
connected to said DC to AC circuit; a rectifying circuit connected
to the secondary winding of said transformer for rectifying said
second AC voltage to said output DC voltage wherein said rectifying
circuit comprises four full-bridge rectifier diodes; a filtering
capacitor connected to said rectifying circuit for filtering said
output DC voltage; a first input DC voltage switching element
wherein the junction point of said first input DC voltage switching
element is connected to said first input capacitor and the ends of
said first input DC voltage switching element are connected with
said second arm of said full-bridge switching devices; and a second
input DC voltage switching element wherein the junction point of
said second input DC voltage switching element is connected to said
second input capacitor and the ends of said second input DC voltage
switching element are connected with said first arm of said
full-bridge switching devices.
2. The integral DC to DC converter according to claim 1, wherein
said first input capacitor is parallel with the first arm of said
full-bridge switching devices and said second input capacitor is
parallel with the second arm of said full-bridge switching
devices.
3. The integral DC to DC converter according to claim 1, wherein
said rectifying circuit further comprises an output voltage
switching element.
4. The integral DC to DC converter according to claim 3, wherein
the junction point of said output voltage switching element is
connected to said filtering capacitor and the ends of said output
voltage switching element are connected with the co-anode of said
four full-bridge rectifier diodes and the central tapping head of
said transformer.
5. An integral DC to DC converter for converting an input DC
voltage into at least one output DC voltage, comprising: an input
capacitor for providing said input DC voltage; a DC to AC circuit
connected with said input capacitor for converting said input DC
voltage to a high frequency first AC voltage wherein said DC to AC
circuit comprises four full-bridge switching devices; a transformer
for converting said first AC voltage into a second AC voltage
wherein the primary winding of said transformer is connected to
said DC to AC circuit; a rectifying circuit connected to the
secondary winding of said transformer for rectifying said second AC
voltage to said output DC voltage wherein said rectifying circuit
comprises four full-bridge rectifier diodes; a filtering capacitor
connected to said rectifying circuit for filtering said output DC
voltage; and an output voltage switching element wherein the
junction point of said output voltage switching element is
connected to said filtering capacitor and the ends of said output
voltage switching element are connected with the co-anode of said
four full-bridge rectifier diodes and the central tapping head of
said transformer.
6. An integral DC to DC converter for converting at least one input
DC voltage into at least one output DC voltage, comprising: a first
input capacitor and a second input capacitor for providing said at
least one input DC voltage; a DC to AC circuit connected with said
first input capacitor and said second input capacitor for
converting said input DC voltage to a high frequency first AC
voltage wherein said DC to AC circuit comprises four full-bridge
switching devices; a transformer for converting said first AC
voltage into a second AC voltage wherein the primary winding of
said transformer is connected to said DC to AC circuit; a
rectifying circuit connected to the secondary winding of said
transformer for rectifying said second AC voltage to said output DC
voltage wherein said rectifying circuit comprises four full-bridge
rectifier diodes; a filtering capacitor connected to said
rectifying circuit for filtering said output DC voltage; a first
input DC voltage switching element wherein the junction point of
said first input DC voltage switching element is connected to said
first input capacitor and the ends of said first input DC voltage
switching element are connected with said second arm of said
full-bridge switching devices; and a second input DC voltage
switching element wherein the junction point of said second input
DC voltage switching element is connected to said second input
capacitor and the ends of said second input DC voltage switching
element are connected with said first arm of said full-bridge
switching devices; and an output voltage switching element wherein
the junction point of said output voltage switching element is
connected to said filtering capacitor and the ends of said output
voltage switching element are connected with the co-anode of said
four full-bridge rectifier diodes and the central tapping head of
said transformer.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a DC to DC converter, and
more particularly to an integral DC to DC converter for converting
at least an input DC voltage into at least an output DC
voltage.
BACKGROUND OF THE INVENTION
[0002] FIG. 1 is a circuit diagram of a full-bridge phase-shifted
soft-switching DC to DC converter according to the prior art. The
DC voltage inputted into the input capacitor C11 is converted into
a high frequency square-wave AC voltage through the switching
devices S11 to S14 and sent to the primary winding of the
transformer Tr. The secondary winding of the transformer Tr outputs
two sets of square-wave alternative voltages having the same
amplitudes, which are then rectified by the rectifier diode D11 and
D12 and filtered by a filtering circuit composed of the inductor Lo
and the capacitor C3 in series to obtain an output DC voltage. The
two switching devices in the first arm of the full-bridge, i.e. S11
and S12, and the two switching devices in the second arm of the
full-bridge, i.e. S13 and S14, are complementarily driven out of
phase at 50% duty ratio of square-wave control signal. The output
voltage is regulated by varying the phase shift of the control
signal in the first arm and the control signal in the second arm.
In addition, the operation efficiency of the converter could be
increased by using the stored energy in the inductor Lk in the
input loop of the transformer Tr to perform the soft turn-on of the
switching devices S11 to S14.
[0003] FIG. 2 is a circuit diagram of an asymmetric half-bridge DC
to DC converter according to the prior art. The DC voltage inputted
into the input capacitor C21 is converted into a high frequency
square-wave AC voltage through the switching devices S21 and S22. -
The DC components existing in the high frequency square-wave AC
voltage is then filtered via the blocking capacitor Cb so as to
send a square-wave AC voltage to the primary winding of the
transformer Tr. The circuit loop in the secondary section of the
transformer Tr includes rectifier diodes D21, D22, a inductor Lo
and a capacitor C3, wherein the output DC voltage is regulated by
varying the square-wave pulse time of the control signal of the
switching devices S21, S22. In addition, the soft turn-on of the
switching devices S21 and S22 is performed by using the stored
energy in the inductor Lk in the input loop of the transformer
Tr.
[0004] FIG. 3 is a circuit diagram of a full-bridge series-parallel
resonant DC to DC converter according to the prior art. The DC
voltage inputted into the capacitor C31 is converted into a high
frequency square-wave AC voltage through the switching devices S31
to S34. The high frequency square-wave AC voltage is resonated by
the series resonance circuit composed of a series resonant inductor
Ls and a series resonant capacitor Cs and the parallel resonant
circuit composed of a parallel resonant capacitor Cp and the input
magnetizing inductor of the transformer Tr, thereby obtaining a
sinusoidal alternative voltage as the input voltage of the
transformer Tr. The circuit loop in the secondary section of the
transformer Tr includes rectifier diodes D31, D32, a inductor Lo
and a capacitor C3, wherein the output DC voltage is regulated by
varying the switching frequency of the switching devices S31 to S34
to change the input voltage of the transformer Tr.
[0005] The DC-to-DC converters described in FIGS. 1 to 3 are
suitable for the condition where the relative change of the input
DC voltage and the output DC voltage is not wide. The operation
performance and the converting efficiency of the DC to DC converter
are decreased with the decreasing output voltage and the increasing
input voltage. Furthermore, the DC to DC converter described above
can be applied to the condition where only one input DC voltage is
converted into one output DC voltage, which is costly and not
environmentally friendly.
[0006] Therefore, the present invention provides an integral DC to
DC converter capable of converting at least one input DC voltage
into at least one output DC voltage for overcoming the problems
described above.
SUMMARY OF THE INVENTION
[0007] It is an object of the present invention to provide an
integral DC to DC converter capable of converting at least one
input DC voltage into an output DC voltage.
[0008] The integral DC to DC converter capable of converting at
least one input DC voltage into an output DC voltage according to
the present invention includes a first input capacitor and a second
input capacitor, a DC to AC circuit, a transformer, a rectifying
circuit, a filtering capacitor, a first input DC voltage switching
element and a second input DC voltage switching element.
[0009] In accordance with an aspect of the present invention, the
first input capacitor and the second input capacitor is used for
providing the at least one input DC voltage. The DC to AC circuit
is connected with the first input capacitor and the second input
capacitor for converting the input DC voltage to a high frequency
first AC voltage and the DC to AC circuit includes four full-bridge
switching devices. The transformer is used for converting the first
AC voltage into a second AC voltage wherein the primary winding of
the transformer is connected to the DC to AC circuit. The
rectifying circuit is connected to the secondary winding of the
transformer for rectifying the second AC voltage to the output DC
voltage and the rectifying circuit includes four full-bridge
rectifier diodes. The filtering capacitor is connected to the
rectifying circuit for filtering the output DC voltage. The
junction point of the first input DC voltage switching element is
connected to the first input capacitor and the ends of the first
input DC voltage switching element are connected with the second
arm of the full-bridge switching devices. The junction point of the
second input DC voltage switching element is connected to the
second input capacitor and the ends of the second input DC voltage
switching element are connected with the first arm of full-bridge
switching devices.
[0010] Preferably, the first input capacitor is parallel with the
first arm of the full-bridge switching devices and the second input
capacitor is parallel with the second arm of the full-bridge
switching devices.
[0011] Preferably, the rectifying circuit further comprises an
output voltage switching element. The junction point of the output
voltage switching element is connected to the filtering capacitor
and the ends of the output voltage switching element are connected
with the co-anode of the four full-bridge rectifier diodes and the
central tapping head of the transformer.
[0012] Preferably, the at least one input DC voltage includes 200 V
and 400 V.
[0013] It is another object of the present invention to provide an
integral DC to DC converter for converting an input DC voltage into
at least one output DC voltage, which includes an input capacitor
for providing the input DC voltage, a DC to AC circuit connected
with the input capacitor for converting the input DC voltage to a
high frequency first AC voltage wherein the DC to AC circuit
comprises four full-bridge switching devices, a transformer for
converting the first AC voltage into a second AC voltage wherein
the primary winding of the transformer is connected to the DC to AC
circuit, a rectifying circuit connected to the secondary winding of
the transformer for rectifying the second AC voltage to the output
DC voltage wherein the rectifying circuit comprises four
full-bridge rectifier diodes, a filtering capacitor connected to
the rectifying circuit for filtering the output DC voltage, and an
output voltage switching element wherein the junction point of the
output voltage switching element is connected to the filtering
capacitor and the ends of the output voltage switching element are
connected with the co-anode of the four full-bridge rectifier
diodes and the central tapping head of the transformer.
[0014] Preferably, the at least one output DC voltage includes 24 V
and 48 V.
[0015] It is another object of the present invention to provide an
integral DC to DC converter for converting at least one input DC
voltage into at least one output DC voltage, which includes a first
input capacitor and a second input capacitor for providing the at
least one input DC voltage, a DC to AC circuit connected with the
first input capacitor and the second input capacitor for converting
the input DC voltage to a high frequency first AC voltage wherein
the DC to AC circuit comprises four full-bridge switching devices,
a transformer for converting the first AC voltage into a second AC
voltage wherein the primary winding of the transformer is connected
to the DC to AC circuit, a rectifying circuit connected to the
secondary winding of the transformer for rectifying the second AC
voltage to the output DC voltage wherein the rectifying circuit
comprises four full-bridge rectifier diodes, a filtering capacitor
connected to the rectifying circuit for filtering the output DC
voltage, a first input DC voltage switching element wherein the
junction point of the first input DC voltage switching element is
connected to the first input capacitor and the ends of the first
input DC voltage switching element are connected with the second
arm, and a second input DC voltage switching element wherein the
junction point of the second input DC voltage switching element is
connected to the second input capacitor and the ends of the second
input DC voltage switching element are connected with the first
arm, and an output voltage switching element wherein the junction
point of the output voltage switching element is connected to the
filtering capacitor and the ends of the output voltage switching
element are connected with the co-anode of the four full-bridge
rectifier diodes and the central tapping head of the
transformer.
[0016] The above objects and advantages of the present invention
will become more readily apparent to those ordinarily skilled in
the art after reviewing the following detailed description and
accompanying drawings, in which:
BRIEF DESCRIPTION OF THE DRAWING
[0017] FIG. 1 is a circuit diagram of a full-bridge phase-shifted
soft-switching DC to DC converter according to the prior art;
[0018] FIG. 2 is a circuit diagram of an asymmetric half-bridge DC
to DC converter according to the prior art;
[0019] FIG. 3 is a circuit diagram of a full-bridge serial-parallel
resonant DC to DC converter according to the prior art;
[0020] FIG. 4 is a circuit diagram of an integral DC to DC
converter according to the first preferred embodiment of the
present invention;
[0021] FIG. 5A is a circuit diagram illustrating the switching
element of the rectifying circuit in FIG. 4 is switched to the
junction point A;
[0022] FIG. 5B is a circuit diagram illustrating the switching
element of the rectifying circuit in FIG. 4 is switched to the
junction point B;
[0023] FIG. 6 is a circuit diagram of an integral DC to DC
converter according to the second preferred embodiment of the
present invention;
[0024] FIG. 7A is a circuit diagram illustrating the first input DC
voltage switching element in FIG. 6 is switched to the junction
point E1 and the second input DC voltage switching element is
switched to the junction point F2;
[0025] FIG. 7B is a circuit diagram illustrating the first DC
voltage switching element in FIG. 6 is switched to the junction
point F1 and the second input DC voltage switching element is
switched to the junction point E2; and
[0026] FIG. 8 is a circuit diagram of an integral DC to DC
converter according to the third preferred embodiment of the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] Referring to FIG. 4, the integral DC to DC converter for the
first preferred embodiment of the present invention is implemented
by varying the structure of the output circuit. The integral DC to
DC converter includes an input capacitor C1, a set of full-bridge
switching devices S1 to S4, a resonance circuit composed of a
resonant inductor Ls and a series resonant capacitor Cs, a
transformer, a rectifying circuit composed of four rectifier diodes
D1 to D4, and a filtering capacitor C3. The input capacitor C1 is
connected with the full-bridge switching devices S1 to S4. The
operations of the full-bridge switching devices S1 to S4 are the
same as those of the typical full-bridge -switching devices by
being alternately conducted and shut. Therefore, the DC voltage in
the input capacitor C1 is converted into a high frequency
alternative voltage. The full-bridge switching devices S1 to S4 are
connected with the resonance circuit composed of the resonant
inductor Ls and the series resonant capacitor Cs to form a DC to AC
converting circuit. Certainly, the resonant inductor Ls can be
integrated with the transformer Tr.
[0028] The transformer Tr is used for electrically isolation and
converting the AC voltage outputted from the DC to AC converting
circuit. The converting ratio depends on the demand. The rectifying
circuit composed of four rectifier diodes D1 to D4 is operated in a
full-bridge scheme. The converter circuit according to the present
invention further includes an output voltage switching element Sm,
wherein one end of the output voltage switching element Sm is
connected to the co-anode of the four full-bridge rectifier diodes
D1 to D4 and the other end of output voltage switching element Sm
is connected to the central tapping head of the transformer Tr. The
co-cathode of the tapping head of the transformer Tr is connected
to the filtering capacitor C3.
[0029] The operation principle of the full-bridge rectifying
circuit of the integral DC to DC converter shown in FIG. 4 will be
explained in more detail below. The full-bridge switching devices
in the first bridge arm, i.e. S1 and S2, are complementarily
conducted and shut by a control signal. The full-bridge switching
devices in the second bridge arm, i.e. S3 and S4, are
complementarily conducted and shut by a corresponding control
signal. The DC voltage in the input capacitor C1 is converted
through the switching devices S1 to S4 to obtain a high frequency
square-wave AC voltage between the midpoint of the first bridge
ann, i.e. A1, and the midpoint of the second bridge arm, i.e. B1.
The high frequency square-wave AC voltage is applied to the series
resonance circuit composed of the series resonant capacitor Cs, the
primary winding of the transformer Tr and the series resonant
inductor Ls to generate a series resonance, thereby forming a
sinusoidal AC current in the primary winding of the transformer Tr.
The sinusoidal AC current is then transferred into the upper and
lower secondary windings of the transformer Tr and sent to the
rectifying circuit composed of diodes D1 to D4. If the output
voltage switching element Sm is switched to the point A, the
alternative current outputted from the transformer Tr will pass
through the rectifier diodes D1 and D2, as can be seen in FIG. 5A;
if the output voltage switching element Sm is switched to the point
B, the alternative current outputted from the transformer Tr will
pass through the rectifier diodes D1 to D4, as can be seen in FIG.
5B. Subsequently, the rectified voltage is sent to the filtering
capacitor C3 for being filtered into the output DC voltage. Because
the output DC voltage is rectified by passing through the rectifier
diodes D1 and D2 when the output switching element Sm is switched
to the point A, the amplitude of the output DC voltage depends on
the voltage amplitude of the upper or lower secondary winding of
the transformer Tr. Because the output DC voltage is rectified by
passing through the rectifier diodes D1, D4 and D2, D3 when the
output voltage switching element Sm is switched to the point B, the
amplitude of the output DC voltage is the summation of the voltage
amplitudes outputted from the upper and the lower secondary
windings of the transformer Tr. Thus, the output DC voltage in the
case the output voltage switching element Sm is switched to point A
is a half of that in the case the switching element Sm is switched
to the point B. In another words, the output DC voltage in the case
the output voltage switching element Sm is switched to the point B
is twice as big as that in the case the output switching element Sm
is switched to the point A. It is apparent that two output DC
voltages can be achieved in the integral DC to DC converter
according to the present invention by adjusting the output voltage
switching element Sm. For example, the two customarily used direct
voltages 24 V and 48 V for communication power supply can be
obtained by using only one integral DC to DC converter according to
the present invention.
[0030] Referring to FIG. 6, the integral DC to DC converter for the
second preferred embodiment of the present invention is implemented
by varying the structure of the input circuit. In this embodiment,
the integral DC to DC converter includes two input capacitor C1A
and C1B, four full-bridge switching devices S1 to S4, two input
voltage switching elements Sm1 and Sm2. The first input capacitor
C1A is in parallel with the full-bridge switching devices in the
first bridge arm, i.e. S1 and S2, and the second input capacitor
C1B is in parallel with the full-bridge switching devices in the
second bridge arm, i.e. S3 and S4. The junction point of the first
input voltage switching element Sm1 is connected with the first
input capacitor C1A, and the ends of the first input voltage
switching element Sm1 are connected with the second bridge arm. The
junction point of the second input voltage switching element Sm2 is
connected with the second input capacitor C1B, and the ends of the
second input voltage switching element Sm2 are connected with the
first bridge arm.
[0031] The operation principle of the integral DC to DC converter
shown in FIG. 6 will be explained in more detail below. When the
first input voltage switching element Sm1 and the second input
voltage switching element Sm2 are switched to the positions E1 and
F2 respectively, the second input capacitor C1B is in parallel with
the first input capacitor C1A, as can be seen in FIG. 7A. Referring
to FIG. 7A, the circuit structure and the operation principle are
the same as those in FIG. 1 except that the input capacitor C1 is
replaced by the first input capacitor C1A in parallel with the
second input capacitor C1B. The voltage amplitude between the
midpoint point of the first bridge arm, i.e. A1, and the midpoint
of the second bridge arm, i.e. A2, is the same as the voltage
amplitude of the first input capacitor C1A or the second input
capacitor C1B which is equal to the input direct voltage U.
[0032] When the fist input voltage switching element Sm1 and the
second input voltage switching element Sm2 in FIG. 6 are switched
to the positions F1 and E2 respectively, the second input capacitor
C1B is in series with the first input capacitor C1A, as can be seen
in FIG. 7B. Referring to FIG. 7B, the first input capacitor CIA
provides voltage to the first bridge arm which is composed of the
switching devices S1 and S2, and the second input capacitor C1B
provides voltage to the second bridge arm which is composed of the
switching device S3 and S4. Because the first input capacitor C1A
is in series with the second input capacitor C1B, each of the
voltage amplitude in the first input capacitor C1A and the voltage
amplitude in the second input capacitor C1B is equal to half the
voltage amplitude of input direct voltage U, i.e. 1/2 U.
[0033] It is apparent that two different input DC voltages can be
applied to achieve an equal output DC voltage according to the
integral DC to DC converter of the present invention by adjusting
the input switching elements Sm1 and Sm2. For example, the
customarily used voltage 24 V for communication power supply can be
obtained by converting two input voltages 200 V and 400 V according
to the present invention.
[0034] The circuit shown in FIG. 4 is provided for converting DC
voltage by varying the output circuit. The circuit shown in FIG. 6
is provided for converting DC voltage by varying the input circuit.
FIG. 8 shows the third preferred embodiment of the present
invention in combination of the circuit in FIG. 4 and the circuit
in FIG. 6. The operation principle is the same as the foregoing
explanation in FIGS. 4 to 7.
[0035] While the invention has been described in terms of what are
presently considered to be the most practical and preferred
embodiments, it is to be understood that the invention needs not be
limited to the disclosed embodiment. On the contrary, it is
intended to cover various modifications and similar arrangements
included within the spirit and scope of the appended claims which
are to be accorded with the broadest interpretation so as to
encompass all such modifications and similar structure.
* * * * *