U.S. patent application number 16/234191 was filed with the patent office on 2019-05-02 for bi-directional dc-dc converter.
The applicant listed for this patent is Huawei Technologies Co., Ltd.. Invention is credited to Cicero DA SILVEIRA POSTIGLIONE, Fernando RUIZ GOMEZ, Grover Victor TORRICO-BASCOPE.
Application Number | 20190131880 16/234191 |
Document ID | / |
Family ID | 51211257 |
Filed Date | 2019-05-02 |
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United States Patent
Application |
20190131880 |
Kind Code |
A1 |
TORRICO-BASCOPE; Grover Victor ;
et al. |
May 2, 2019 |
BI-DIRECTIONAL DC-DC CONVERTER
Abstract
The present invention relates to a bi-directional DC-DC
converter comprising: a first terminal, a second terminal, a
transformer circuit, a first high voltage side coupled to said
first terminal, and a second low voltage side coupled to said
second terminal; wherein said first high voltage side and said
second low voltage side are coupled to each other by means of said
transformer circuit, and said first high voltage side comprises a
resonant tank circuit coupled between a first bridge circuit of
said first high voltage side and a high voltage side of said
transformer circuit. Furthermore, the invention also relates to a
system comprising at least two such bi-directional DC-DC
converters.
Inventors: |
TORRICO-BASCOPE; Grover Victor;
(Kista, SE) ; RUIZ GOMEZ; Fernando; (Kista,
SE) ; DA SILVEIRA POSTIGLIONE; Cicero; (Kista,
SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Huawei Technologies Co., Ltd. |
Shenzhen |
|
CN |
|
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Family ID: |
51211257 |
Appl. No.: |
16/234191 |
Filed: |
December 27, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15828736 |
Dec 1, 2017 |
10193459 |
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16234191 |
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15250477 |
Aug 29, 2016 |
9876434 |
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15828736 |
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PCT/EP2014/065643 |
Jul 21, 2014 |
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15250477 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
Y02B 70/1491 20130101;
H02M 3/33584 20130101; H02M 2007/4811 20130101; H02M 1/15 20130101;
H02M 3/33546 20130101; H02M 2007/4815 20130101; H02M 2001/0058
20130101; Y02B 70/1433 20130101; Y02B 70/10 20130101 |
International
Class: |
H02M 3/335 20060101
H02M003/335; H02M 1/15 20060101 H02M001/15 |
Claims
1. A bi-directional DC-DC converter, comprising: a first terminal
circuit; a second terminal circuit; a transformer circuit; a first
high voltage side coupled to the first terminal circuit; and a
second low voltage side coupled to the second terminal circuit;
wherein the first high voltage side and the second low voltage side
are coupled to each other via the transformer circuit; and wherein
the first high voltage side comprises a resonant tank circuit
coupled between a first bridge circuit of the first high voltage
side and a high voltage side of the transformer circuit wherein the
resonant tank circuit comprises: a first branch comprising a first
capacitor C.sub.r2 and a first inductor L.sub.r1 coupled in series;
a second capacitor C.sub.r2; and a second inductor L.sub.r2;
wherein the first branch, the second inductor L.sub.r2 and the
second capacitor C.sub.r2 are coupled to a common node; wherein the
second capacitor C.sub.r2 is coupled between the common node and a
first terminal of the high voltage side of the transformer circuit;
and wherein the second inductor L.sub.r2 is coupled between the
common node and a second terminal of the high voltage side of the
transformer circuit; wherein: a first terminal of the first
capacitor C.sub.r1 forms a first terminal of the resonant tank
circuit; a second terminal of the first capacitor C.sub.r1 is
connected to a first terminal of the first inductor L.sub.r1; a
second terminal of the first inductor L.sub.r1 is connected to a
first terminal of the second capacitor C.sub.r2 and to a first
terminal of the second inductor L.sub.r2; a second terminal of the
second inductor L.sub.r2 forms a third terminal of the resonant
tank circuit; and a second terminal of the second capacitor
C.sub.r2 forms a second terminal of the resonant tank circuit.
2. The bi-directional DC-DC converter according to claim 1,
wherein: the first terminal of the resonant tank circuit and the
third terminal of the resonant tank circuit are connected to the
first bridge circuit; and the second terminal of the resonant tank
circuit and the third terminal of the resonant tank circuit are
connected to the high voltage side of the transformer circuit.
3. The bi-directional DC-DC converter according to claim 1,
wherein: the first bridge circuit is a full bridge and the second
low voltage side comprises a further full bridge coupled to a low
voltage side of the transformer circuit; or the first bridge
circuit is a half bridge, the second low voltage side comprises a
push-pull circuit connected to the low voltage side of the
transformer circuit and the transformer circuit comprises on its
low voltage side a second winding comprising a center tap; or the
first bridge circuit is a half bridge and the second low voltage
side comprises a push-pull circuit with an autotransformer
connected to the low voltage side of the transformer circuit.
4. The bi-directional DC-DC converter according to claim 1, further
comprising: a first filter coupled in parallel with the first
bridge circuit.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/828,736, filed on Dec. 1, 2017, which is a
continuation of U.S. patent application Ser. No. 15/250,477, filed
on Aug. 29, 2016, now U.S. Pat. No. 9,876,434, which is a
continuation of International Application No. PCT/EP2014/065643,
filed on Jul. 21, 2014. All of the afore-mentioned patent
applications are hereby incorporated by reference in their
entireties.
TECHNICAL FIELD
[0002] The present invention relates to a bi-directional DC-DC
converter. Furthermore, the invention also relates to a system
comprising at least two such bi-directional DC-DC converters.
BACKGROUND
[0003] The developing trends of Isolated Bidirectional Direct
Current-Direct Current (DC-DC) Converters (IBDC) are Wide
Input--Wide Output (WIWO) voltage for very high efficiency, high
power density and low cost. The resonant DC-DC converters are
suitable technology to achieve high efficiency due to its intrinsic
feature to achieve soft switching (Zero Voltage Switching, ZVS, and
Zero Current Switching, ZCS). Furthermore, it is possible in these
circuits to increase the switching frequency in order to reduce the
size of the reactive components.
[0004] Common and widely used bidirectional DC-DC converters found
in the industry today are the Dual Active Bridge (DAB) and resonant
converters due to their availability to achieve high
efficiency.
[0005] However, there are still remaining drawbacks regarding the
conventional resonant converters at bidirectional operation (i.e.
forward-and reverse-mode), e.g. mainly the voltage gain
characteristic at reverse mode of operation. Furthermore, the high
AC-current at the low voltage side of the output filter resulting
in high power losses and large volume of the filter if the current
technology is going to be used.
[0006] With the described bidirectional topological circuits
according to conventional solutions the current stress on the
resonant components on the low voltage side is high and compromises
the efficiency of the converter.
[0007] Also, with the described bidirectional topological circuits
according to conventional solutions it is not possible to achieve
WIWO voltage and high efficiency. Moreover, it is very hard to get
new topological circuits with reduced number of the active
components (controlled semiconductors) where high reliability and
performance in bidirectional energy conversion systems are
required.
SUMMARY
[0008] An objective of the invention is to provide a concept which
mitigates or solves the drawbacks and problems of conventional
solutions.
[0009] Another objective of the present invention is to provide
improved bi-directional converters for WIWO voltage applications in
power systems.
[0010] According to a first aspect of the present invention, the
above mentioned and other objective is achieved with a
bi-directional DC-DC converter comprising: [0011] a first terminal
circuit, [0012] a second terminal circuit, [0013] a transformer
circuit, [0014] a first high voltage side coupled to said first
terminal circuit, and [0015] a second low voltage side coupled to
said second terminal circuit; wherein [0016] said first high
voltage side and said second low voltage side are coupled to each
other by means of said transformer circuit, and [0017] said first
high voltage side comprises a resonant tank circuit coupled between
a first bridge circuit of said first high voltage side and a high
voltage side of said transformer circuit.
[0018] The bridge circuits of the present converter may comprise
active switches according to an implementation form of the first
aspect.
[0019] With converters according to embodiments of the present
invention very high variation of the input and output voltage,
narrow frequency variation for voltage regulation, high efficiency,
high power density and low cost can be achieved due the at least
the following points. The present converter has simplified and more
efficient layout due to the placement of the resonant tank on the
high voltage side. This will also reduce the current stress and
consequently the losses of the converter.
[0020] Furthermore, no energy storage elements in the low voltage
side of the converter are needed in order to get ZVS. Embodiments
of the present invention can provide ZVS and ZCS in both directions
of the converter.
[0021] Also, increased reliability is provided due to reduced
number of the synchronous drivers for the low voltage side
semiconductors but also due to the common reference that can be
used.
[0022] The internal energy consumption needed is also reduced with
the present circuit layout which will increase the efficiency of
the converters according to the present invention compared to
conventional converters.
[0023] According to a first implementation form of the first aspect
as such, said resonant tank circuit comprises: a first branch
comprising a first capacitance C.sub.r1 and a first inductance
L.sub.r1 coupled in series with each other, a second capacitance
C.sub.r2 and a second inductance L.sub.r2; wherein said first
branch, said second inductance L.sub.r2 and said second capacitance
are coupled to a common node; wherein said second capacitance
C.sub.r2 is coupled between said common node and a first terminal
of said high voltage side of said transformer circuit; wherein said
second inductance L.sub.r2 is coupled between said common node (C)
and a second terminal of said high voltage side of said transformer
circuit.
[0024] This can be denoted as a
Capacitor-Inductor-Inductor-Capacitor (CLLC) type resonant tank.
Therefore, reduced number of the active semiconductors at high
voltage side and low voltage side are needed.
[0025] According to a second implementation form of the first
implementation form of the first aspect, [0026] a first terminal of
the first capacitance C.sub.r1 forms a first (connection) terminal
of said resonant tank circuit, [0027] a second terminal of the
first capacitance C.sub.r1 is connected to a first terminal of the
first inductance L.sub.r1; [0028] a second terminal of the first
inductance L.sub.r1 is connected to a first terminal of the second
capacitance C.sub.r2 and to a first terminal of the second
inductance L.sub.r2; [0029] a second terminal of the second
inductance L.sub.r2 forms a third (connection) terminal of said
resonant tank circuit; [0030] a second terminal of the second
capacitance C.sub.r2 forms a second (connection) terminal of said
resonant tank circuit.
[0031] According to a third implementation form of the second
implementation form of the first aspect, [0032] said first terminal
of said resonant tank circuit and said third terminal of said
resonant tank circuit are connected to said first bridge circuit;
and [0033] said second terminal of said resonant tank circuit and
said third terminal of said resonant tank circuit are connected to
said high voltage side of said transformer circuit.
[0034] According to a fourth implementation form of the first or
second implementation forms of the first aspect, said first bridge
circuit is a full bridge and said second low voltage side comprises
a further full bridge coupled to a low voltage side of said
transformer circuit, or said first bridge circuit is a half bridge,
said second low voltage side comprises a push-pull circuit
connected to the low voltage side of the transformer circuit and
said transformer circuit comprises on its low voltage side a second
winding comprising a center tap, or said first bridge circuit is a
half bridge and said second low voltage side comprises a push-pull
circuit with an autotransformer connected to the low voltage side
of the transformer circuit. Hence, the present resonant tank can be
added to any converter topology for different applications.
[0035] According to a fifth implementation form of the fourth
implementation of the first aspect, said resonant tank circuit
comprises: a first branch comprising a first capacitance C.sub.r1
and a first inductance L.sub.r1 coupled in series with each other,
a second branch comprising a second inductance L.sub.r2, a second
capacitance C.sub.r2 coupled in series with each other, a third
branch comprising a third capacitance C.sub.r3 and a third
inductance L.sub.r3 coupled in series with each other; wherein said
first branch, second branch and third branch are coupled to a
common node (C); wherein said second branch is coupled between said
common node and a first terminal of said high voltage side of said
transformer circuit; and wherein said third branch is coupled
between said common node and a second terminal of said high voltage
side of said transformer circuit. This can be denoted as an
Inductor-Capacitor-Inductor-Capacitor-Inductor-Capacitor or 3LC
type resonant tank. Therefore, reduced number of the active
semiconductors at high voltage side and low voltage side are
needed. Further, the voltage gain characteristic is greater than 1,
only with passive components and boost and buck mode of operation
is possible.
[0036] According to a sixth implementation form of the fifth
implementation form of the first aspect,
[0037] a first terminal of the first capacitance C.sub.r1 forms a
first (connection) terminal of said resonant tank circuit; [0038] a
second terminal of the first capacitance C.sub.r1 is connected to a
first terminal of the first inductance L.sub.r1; [0039] a second
terminal of the first inductance L.sub.r1 is connected to a first
terminal of the second inductance L.sub.r2 and to a first terminal
of the third inductance L.sub.r3; [0040] a second terminal of the
second inductance L.sub.r2 is connected to a first terminal of the
second capacitance C.sub.r2; [0041] a second terminal of the second
capacitance C.sub.r2 forms a second (connection) terminal of said
resonant tank circuit; [0042] a second terminal of the third
inductance L.sub.r3 is connected to a first terminal of the third
capacitance C.sub.r3; [0043] a second terminal of the third
capacitance C.sub.r3 forms a third (connection) terminal of said
resonant tank circuit.
[0044] According to a seventh implementation form of the sixth
implementation form of the first aspect, [0045] said first
(connection) terminal of said resonant tank circuit and said third
(connection) terminal of said resonant tank circuit are connected
to said first bridge circuit; and [0046] said second (connection)
terminal of said resonant tank circuit and said third (connection)
terminal of said resonant tank circuit are connected to the high
voltage side of said transformer.
[0047] According to an eighth implementation form of any of the
fifth to seventh implementation forms of the first aspect, said
first bridge circuit is a full bridge and said second low voltage
side comprises a further full bridge coupled to a low voltage side
of said transformer circuit, or said first bridge circuit is a half
bridge and said second low voltage side comprises a full bridge
coupled to a low voltage side of said transformer circuit, or said
first bridge circuit is a half bridge, said second low voltage side
comprises a push-pull circuit connected to the low voltage side of
the transformer circuit and said transformer circuit comprises on
its low voltage side a second winding comprising a center tap, or
said first bridge circuit is a half bridge and said second low
voltage side comprises a push-pull circuit with an autotransformer
connected to the low voltage side of the transformer circuit.
Hence, the present resonant tank circuit can be added to any
converter topology for different applications.
[0048] According to a ninth implementation form of any of the fifth
to eight implementation forms of the first aspect, at least two of
said first inductance L.sub.r1, said second inductance L.sub.r2 and
said third inductance L.sub.r3 are magnetically coupled to each
other in one common magnetic core. Thereby, the number of
components in the resonant tank circuit can be reduced.
[0049] According to a tenth implementation form of any of the
implementation forms of the first aspect or the first aspect as
such, a second filter is coupled between a positive and a negative
terminal of the second terminal circuit. Thereby noise can be
removed in the low voltage side of the converter.
[0050] According to an eleventh implementation form of any of the
implementation forms of the first aspect or the first aspect as
such, a first filter is coupled in parallel with said first
terminal and said first bridge circuit. Thereby noise can be
removed in the high voltage side of the converter.
[0051] According to a second aspect of the invention, the above
mentioned and other objective is achieved with a bi-directional
DC-DC converter system comprising two or more bi-directional DC-DC
converters according to the first aspect or any implementation form
of the first aspect, wherein said two or more bi-directional DC-DC
converters are interleaved with each other, i.e. the bi-directional
DC-DC converters are coupled with each other in different
configurations.
[0052] Interleaving is to operate two or more DC-DC converters in
parallel and to operate the switches of the bridge circuits of each
respective DC-DC converter with phase difference with respect to
each other. Thereby, the resultant ripple current in the input and
the output of the interleaved system can be minimized.
[0053] Interleaving two or more of the present converters is
preferred for high power applications. Further, interleaving two or
more converters reduces the number of capacitors needed for the
output filter when phase-shifting control is used. It is also
realized that the present converters can be interleaved in a
variety of different serial and parallel configurations well known
in the art.
[0054] According to a first implementation form of the second
aspect as such, said first high voltage sides of said two or more
bi-directional DC-DC converters are coupled in series with each
other.
[0055] According to a second implementation form of the first
implementation form of the second aspect or the second aspect as
such, said first high voltage sides of said two or more
bi-directional DC-DC converters are coupled in parallel with each
other.
[0056] According to a third implementation form of the first or
second implementation forms of the second aspect or the second
aspect as such, said second low voltage sides of said two or more
bi-directional DC-DC converters are coupled in series with each
other.
[0057] According to a fourth implementation form of any of the
first to third implementation forms of the second aspect or the
second aspect as such, said second low voltage sides of said two or
more bi-directional DC-DC converters are coupled in parallel with
each other.
[0058] A further aspect of the present invention relates to an
electrical circuit comprising two or more coupling nodes (or
terminals) for coupling to other electrical circuits and two or
more inductances, wherein said two or more inductances are
magnetically coupled to each other in one common magnetic core.
Thereby, the number of inductive components in the electrical
circuit and also the manufacturing costs are reduced.
[0059] It should be noted that further applications and advantages
of the present converter and system will be apparent from the
following detailed description.
BRIEF DECSRIPTION OF THE DRAWINGS
[0060] The appended drawings are intended to clarify and explain
different embodiments of the present invention, in which:
[0061] FIG. 1 shows a bi-directional DC-DC converter according to
an embodiment of the present invention;
[0062] FIG. 2 shows a CLLC bi-directional DC-DC converter according
to an embodiment of the present invention;
[0063] FIGS. 3a and 3b show voltage gain characteristics for
forward and reverse mode for the CLLC bi-directional DC-DC
converter as shown in FIG. 2;
[0064] FIGS. 4a-4c show other further CLLC bi-directional DC-DC
converters according to embodiments of the present invention;
[0065] FIG. 5 shows a 3LC bi-directional DC-DC converter according
to an embodiment of the present invention;
[0066] FIGS. 6a and 6b show voltage gain characteristics for
forward and reverse mode for the 3LC bi-directional DC-DC converter
as shown in FIG. 5;
[0067] FIGS. 7a-7c show other further 3LC bi-directional DC-DC
converter according to embodiments of the present invention;
[0068] FIGS. 8a and 8b show two different 3LC resonant tanks as
they can be used with the embodiments shown in FIGS. 5 and
7a-7c;
[0069] FIG. 9 shows a bi-directional DC-DC converter system
according to an embodiment of the present invention comprising CLLC
bi-directional DC-DC converters; and
[0070] FIG. 10 shows a bi-directional DC-DC converter system
according to an embodiment of the present invention comprising 3LC
bi-directional DC-DC converters.
DETAILED DESCRIPTION
[0071] FIG. 1 shows a simplified block diagram of a bi-directional
DC-DC converter 100 according to an embodiment of the present
invention. With reference to FIG. 1 the bi-directional DC-DC
converter 100 comprises a (first) High Voltage (HV) (e.g.
connection) terminal circuit 101 of an HV side 107, a (second) Low
Voltage (LV) (e.g. connection) terminal circuit 103 of an LV side
109 and a transformer circuit 105. The HV side 107 is coupled to
the first terminal circuit 101 of the DC-DC converter 100, and the
LV side 109 is coupled to the second terminal circuit 103 of the
DC-DC converter 100.
[0072] Further, the HV side 107 and the LV side 109 are coupled to
each other by means of the mentioned transformer circuit 105.
Moreover, the HV side 107 comprises a resonant tank circuit 111
coupled between a first bridge circuit 113 of the HV side 107 and a
HV side of the transformer (circuit) 105. The terminal circuits 101
and 103 of the converter 100 and the different implementation form
of this converter 100 described in the following typically comprise
a positive terminal (for applying or providing a positive
potential) and a negative terminal (e.g. for applying or providing
a negative or GND potential). These positive and negative terminals
are typically connection terminals adapted for connecting to one or
more other devices. In the forward direction (High voltage in--Low
voltage out) of the converter 100, the first terminal circuit 101
forms in input of the converter 100 and the second terminal circuit
103 forms an output of the converter 100. In the reverse direction
(Low voltage in--High voltage out) of the converter 100, the second
terminal circuit 103 forms in input of the converter 100 and the
first terminal circuit 101 forms an output of the converter
100.
[0073] HV side and LV side mean that at the HV side typically the
comparatively higher voltages are applied/are provided when
compared to the LV side.
[0074] According to an embodiment of the present invention, the
resonant tank circuit 111 is of
Capacitor-Inductor-Inductor-Capacitor (CLLC) type. FIG. 2 shows a
bi-directional DC-DC converter 200 according to an embodiment of
the present invention with a CLLC resonant tank 111. The
bi-directional DC-DC converter 200 forms a possible implementation
form of the bi-directional DC-DC converter 100 as shown in FIG.
1.
[0075] In the CLLC bi-directional DC-DC converter 200 an example of
a CLLC resonant tank 111 implemented in the HV side 107 of the
bi-directional DC-DC converter is shown in FIG. 2. Among the
characteristics of this resonant tank circuit are the possibility
to achieve WIWO voltage range in forward mode and acceptable
voltage gain in reverse mode, but also high efficiency and high
power density.
[0076] With reference to FIG. 2 the resonant tank circuit 111
according to the CLLC embodiment comprises a first capacitance
C.sub.r1, a first inductance L.sub.r1, a second capacitance
C.sub.r2, and a second inductance L.sub.r2.
[0077] A first terminal of the first capacitance C.sub.r1 forms a
first (connection) terminal T1 of the CLLC resonant tank circuit
111. A second terminal of the first capacitance C.sub.r1 is
connected to a first terminal of the first inductance L.sub.r1 . A
second terminal of the first inductance L.sub.r1 is connected to a
first terminal of the second capacitance C.sub.r2 and to a first
terminal of the second inductance L.sub.r2. Further, a second
terminal of the second inductance L.sub.r2 forms a third
(connection) terminal T3 of the resonant tank circuit 111. A second
terminal of the second capacitance C.sub.r2 forms a (second)
connection terminal T2 of the CLLC resonant tank circuit 111.
[0078] Furthermore, the HV side 107 comprises a first full bridge
circuit 113 coupled between the first HV terminal circuit 101 and
the resonant tank circuit 111.
[0079] The first connection terminal T1 of the resonant tank
circuit 111 is connected between third S3 and fourth S4 switches of
the first bridge circuit 113. The third connection terminal T3 of
the resonant tank circuit 111 is connected between first S1 and
second S2 switches of the first bridge circuit 113. The second
connection terminal T2 of the resonant tank circuit 111 is
connected to a first terminal of the HV side (e.g. a first ending
of a first winding) of the transformer circuit 105, and the third
connection terminal T3 of the resonant tank circuit 111 is
connected to a second terminal of the HV side (of a second ending
of the first winding) of the transformer circuit 105.
[0080] In other words the CLLC resonant circuit 111 according to
this embodiment comprises a first branch comprising a first
capacitance C.sub.r1 and a first inductance L.sub.r1 coupled in
series with each other, a second capacitance C.sub.r2 and a second
inductance L.sub.r2. The first branch, said second inductance
L.sub.r2 and said second capacitance are coupled to a common node
C. Said second capacitance C.sub.r2 is coupled between said common
node C and the first terminal of said high voltage side of said
transformer circuit 105. Said second inductance L.sub.r2 is coupled
between said common node C and the second terminal of said high
voltage side of said transformer circuit 105.
[0081] The values for the different capacitances and inductances of
the present resonant tank 111 are dependent on the particular
application.
[0082] The HV side 107 includes the first terminal circuit 101
which is connected to first and second terminals of a first filter
117 implemented as a capacitance C.sub.HV in this particular
example. In detail, the first filter 117 is connected between the
positive terminal and the negative terminal of the first terminal
circuit 101.
[0083] The first and second terminals of the first filter 117 are
in turn connected to a positive terminal and a negative terminal of
the full bridge circuit 113, respectively. The full bridge circuit
113 comprises switches S1, S2, S3 and S4 implemented as N-Channel
Mosfet transistors in this example. However, other implementations
for the switches are possible too (such as Insulated Gate Bipolar
Transistor, IGBT; Metal Oxide Silicon Field Effect Transistor,
MOSFET; Junction Gate Field-Effect Transistor, JFET; Gate Turn-off
Thyristor, GTO).
[0084] Mentioned switches S1, S2, S3 and S4 of the full bridge
circuit 113 of the HV side are followed by the above described CLLC
resonant tank circuit 111 which in turn is connected to the HV side
of the transformer circuit 105. The transformer circuit 105
magnetically couples the HV side 107 and the LV side 109 of the
converter device 200.
[0085] Further, first and second terminals of the LV side (e.g.
endings of a second winding) of the transformer (circuit) 105 are
connected to a second full bridge circuit 115 of the LV side 109.
The second full bridge circuit 115 includes first Sr.sub.1, second
Sr.sub.2, third Sr.sub.3 and fourth Sr.sub.4 switches. A positive
and a negative connection terminals of the second full bridge
circuit 115 are connected to first and second terminals of a second
filter 119 of the LV side 109 which in this example is implemented
as a capacitance C.sub.LV. Finally, the first and second terminals
of the second filter 119 are connected to the second terminal
circuit 103 of the present DC-DC converter 200. In detail, the
first filter 117 is connected between the positive terminal and the
negative terminal of the second terminal circuit 103.
[0086] The voltage gain characteristics for both forward (shown in
FIG. 3a) and reverse mode (shown in FIG. 3b) of this particular
embodiment in FIG. 2 are shown in FIGS. 3a and 3b.
[0087] The y-axis represents the voltage and the x-axis represents
the frequency. As it can be seen in the graphs of FIGS. 3a and 3b,
the natural resonance frequency of the resonant tank is equal in
both directions. In the reverse mode, the voltage gain
characteristic is limited and highly dependent of the quality
factor Q which is dependent on the values of the components in the
resonant tank circuit 111 (in the FIGS. 3a and 3b Q=10, 2 and 0.1
are shown). However, this is a design related issue and will depend
of the choice of the values for the components (parameters) of the
resonant tank and the application.
[0088] Based on the configuration of the LV side 107 of the above
described converter, different topological implementation forms of
the bi-directional DC-DC converter are possible which are
illustrated in FIG. 4a-4c. These implementation forms relate to the
configurations of the first bridge circuit 113 and the second
bridge circuit 105, respectively.
[0089] In the converter 210 shown in FIG. 4a, the first bridge
circuit 113 in the HV-side 107 is implemented as a Half Bridge (HB)
circuit and the second bridge circuit 115 in the LV side 109 is
implemented as a Full Bridge (FB) circuit.
[0090] The HB circuit 113 in the HV side 107 in FIG. 4a comprises
first S1 and second S2 switches; first CB1 and second CB2
capacitances (CB1 and CB2 may be part of the resonant tank circuit
in certain applications when the first bridge circuit has this HB
configuration); and first Dc1 and second Dc2 clamping diodes. The
first connection terminal T1 of the resonant tank circuit 111 is
connected between a series connection of the first capacitance CB1
in parallel with the first clamping diode Dc1 and the second
capacitance CB2 in parallel with the second clamping diode Dc2. The
third connection terminal T3 of the resonant tank circuit 111 is
connected between the series connection of the first switch S1 and
the second switch S2.
[0091] The FB circuit in the LV side 109 in FIG. 4a is configured
in the same way as the FB circuit in FIG. 2 as described above.
[0092] In the converter 220 as shown in FIG. 4b, the first bridge
circuit 113 in the HV-side 107 is implemented as a Half Bridge
circuit (as the one in FIG. 4a). Furthermore, the LV side 107 of
the convert 220 comprises instead of a bridge circuit a push
pull--autotransformer circuit 116.
[0093] The PP--autotransformer circuit 116 in the LV side in FIG.
4b comprises switches Sr1, Sr2 and an autotransformer 123. The
autotransformer 123 has two windings (first and second windings) in
one common core. The first winding is connected the first switch
Sr1, and the second winding is connected to the second switch Sr2.
The midpoint of the autotransformer 123 is connected to a positive
terminal of the LV side. The common point of Sr1 and Sr2 are
connected to a negative terminal of the LV side. Further, the first
terminal of the LV side (e.g. a first ending of a second winding)
of the transformer 105 is connected between the first winding of
the autotransformer 123 and the first switch Sr1. The second
terminal of the LV side (e.g. a second ending of the second
winding) of the transformer 105 is connected between the second
winding of the autotransformer 123 and the second switch Sr2.
[0094] In the converter 230 shown in FIG. 4c, the first bridge
circuit 113 is implemented as HB circuit. Furthermore, the
converter 230 comprises in its LV side instead of a bridge circuit
a Push Pull (PP) Circuit 118. The PP circuit 118 comprises a first
switch Sr1 and a second switch Sr2. In the embodiment shown in FIG.
4c, the first switch Sr1 and the second switch Sr2 are implemented
exemplarily as N-channel Mosfets. The transformer circuit 105 is
implemented as a transformer comprising on its HV side a first
winding connected with its first end to the second terminal T2 and
its second end to the third terminal T3 of the resonant tank
circuit 111. Furthermore, on LV side the transformer comprises a
second winding having a first end, a center tap and a second end. A
first terminal of the first switch Sr1 (e.g. a drain terminal) is
connected to the second end of the second winding. A first terminal
of the second switch Sr2 (e.g. a drain terminal) is connected to
the first end of the second winding. Second terminals (e.g. source
terminals) of the first switch Sr1 and second switch Sr2 are
connected together to a negative terminal of the second terminal
circuit 103. Furthermore, the center tap of the transformer is
connected to the positive terminal of the second terminal circuit
103. A second filter C.sub.LV is connected between the negative and
positive terminal of the second terminal circuit 103.
[0095] According to an embodiment of the present invention, the
tank circuit 111 is of three Inductor-Capacitor type, i.e.
Inductor-Capacitor-Inductor-Capacitor-Inductor-Capacitor, denoted
3LC in this disclosure. FIG. 5 shows such a 3LC resonant tank 111
implemented in the HV side 107 of a bi-directional DC-DC converter
300 according to an embodiment of the to the present invention,
which forms a possible implementation form of the converter 100.
Among the characteristics of this resonant tank circuit 111 are the
possibility to achieve suitable voltage gain in reverse mode, but
also high efficiency and high power density. Another important
effect is that the WIWO voltage range can be achieved with a very
narrow frequency variation.
[0096] From left in FIG. 5 the HV side 107 includes a first
terminal circuit 101 of the HV side which is connected to first and
second terminals of a first filter 117 implemented as a capacitance
in this example, C.sub.HV. The first and second terminals of first
filter 117 are in turn connected to a positive terminal and a
negative terminal of the FB circuit 113 as described above.
Mentioned switches S1, S2, S3 and S4 of the FB circuit 113 of the
HV side are followed by the 3LC resonant tank circuit 111. The FB
circuit is coupled to connection terminals T1 and T3 of the
resonant tank circuit 111. Further, the resonant tank circuit 111
is connected to the LV side of the transformer circuit 105 via
connection terminals T2 and T3. The transformer circuit 105
magnetically couples the HV side 107 and the LV side 109 of the
present converter 300.
[0097] In the example shown in FIG. 5, the LV side 109 of the
converter 300 is implemented as a push pull circuit 118 (comprising
switches Sr.sub.1, Sr.sub.2 in combination with the transformer
circuit 105 having the second winding with center tap (as shown in
FIG. 4c). Hence, the converter 300 differs from the converter 230
in that the resonant tank circuit 111 in the converter 300 is
implemented as 3LC resonant tank.
[0098] Alternatively also an implementation with a push
pull-autotransformer circuit 116 on the LV side 109 would be
possible (as shown in FIG. 4b).
[0099] FIG. 8a shows one proposed 3LC resonant tank 111
configuration for use in embodiments of the present invention which
comprises a first capacitance C.sub.r1, a first inductance
L.sub.r1, a second inductance L.sub.r2, a second capacitance
C.sub.r2, a third inductance L.sub.r3 and a third capacitance
C.sub.r3. A first terminal of the first capacitance C.sub.r1 forms
a first connection terminal T1 of the 3LC resonant tank circuit
111. A second terminal of the first capacitance C.sub.r1 is
connected to a first terminal of the first inductance L.sub.r1. A
second terminal of the first inductance L.sub.r1 is connected to a
first terminal of the second inductance L.sub.r2 and to a first
terminal of the third inductance L.sub.r3. A second terminal of the
second inductance L.sub.r2 is connected to a first terminal of the
second capacitance C.sub.r2. A second terminal of the second
capacitance C.sub.r2 forms a second connection terminal T2 of the
resonant tank circuit 111. A second terminal of the third
inductance L.sub.r3 is connected to a first terminal of the third
capacitance C.sub.r3. A second terminal of the third capacitance
C.sub.r3 forms a third connection terminal T3 of the resonant tank
circuit 111. As can be seen from FIG. 8a, the three inductances
L.sub.r1, L.sub.r2, L.sub.r3 are all connected to a common node
C.
[0100] In other words the proposed 3LC resonant tank configuration
shown in FIG. 8a comprises a first branch comprising a first
capacitance C.sub.r1 and a first inductance L.sub.r1 coupled in
series with each other, a second branch comprising a second
inductance L.sub.r2, a second capacitance C.sub.r2, a third branch
comprising a third capacitance C.sub.r3 and a third inductance
L.sub.r3 coupled in series with each other. The first branch is
coupled in series with the second branch, and the third branch is
coupled between a common node C of the first branch and the second
branch and the third terminal T3 of the resonant tank circuit 111.
The second T2 and the third terminals T3 of the resonant tank
circuit 111 are to be coupled to the high voltage side of the
transformer circuit 105. The values for the different capacitances
and inductances of the present resonant tank 111 are dependent on
the particular application.
[0101] The features of this resonant tank 111 are unique as it
increases the voltage gain for both directions to be greater than 1
which is the gain obtained at the resonant frequency. This feature
makes it possible to achieve WIWO voltage variation.
[0102] The voltage gain characteristics for both forward and
reverse mode are shown in FIG. 6a (forward mode) and 6b (reverse
mode) for the 3LC bi-directional DC-DC converter 300 as shown in
FIG. 5. The y-axis represents the voltage and the x-axis represents
the frequency. As it can be seen in the graphs in FIGS. 6a and 6b,
the natural resonance frequency of the tank is equal in both
directions. The effect introduced by the parallel LC-network
(L.sub.r3 and C.sub.r3) makes the gain to change from 0 to infinity
in a very sharp way. The final value is depending of the quality
factor Q (Q=10, 2, 0.1 are shown in FIGS. 6a and 6b). This result
in high gain, but it is also important to mention that the
characteristics of this converter are the same as the standard LLC
resonant tank for both directions. This guarantees that the
converter will always work in the most optimum power transferring
point in both forward and reverse modes.
[0103] In FIG. 8b a magnetic integration of the first L.sub.r1 and
the second L.sub.r2 inductances of the resonant tank circuit 111
using the same magnet core is illustrated. This simplifies the
building of the 3LC resonant tank circuit 111 of the present
converter and also reduces the number of components. However, all
the inductors of the resonant tank circuit 111 could be integrated
in a single magnetic component. Therefore, embodiments of the
present invention also relate to an electrical circuit 111
comprising two or more coupling nodes for coupling to other
electrical circuits and two or more inductances, wherein the two or
more inductances are magnetically coupled to each other in one
common magnetic core. The present electrical circuit 111 can also
be used in other applications in which two or more inductances are
used.
[0104] Based on the 3LC resonant tank 111, we have different
converter topological circuits that are illustrated (additionally
to the one shown in FIG. 5) in FIG. 7a-7c according to further
embodiments of the present invention.
[0105] The FB, HB and PP circuits in FIG. 7a-7c are configured in
the same way as the FB, HB and PP circuits in the embodiments shown
in FIG. 2, 4a, 4b. FIG. 7a shows a Full Bridge--Full Bridge
implementation for the bridge circuits 113, 115 as the one in FIG.
2. FIG. 7b shows a Half Bridge--Full Bridge implementation for the
bridge circuits 113, 115 as the one shown in FIG. 4a. FIG. 7c shows
a Half Bridge--Push Pull circuit with Autotransformer
implementation for the bridge circuit 113 and LV side 109 as the
one shown in FIG. 4b.
[0106] For high power applications, interleaving two or more DC-DC
converters of embodiments of the present invention is preferred so
as to obtain a bi-directional DC-DC converter system.
[0107] For instance, one possible configuration is to have series
connection of the HV sides 107a, 107b, . . . , 107n of the DC-DC
converters and parallel connection of the LV sides 109a, 109b, 109n
of the DC-DC converters. This configuration setup is illustrated in
the systems in FIGS. 9 and 10, respectively. The single DC-DC
converter can be of any type according to embodiments of the
present invention.
[0108] Other configurations for the connection of the individual
converters the system 1000 are: in parallel in the HV side 107 and
in series in the LV side 109, in series in the HV side 107 and in
series in the LV side 109, and in parallel in the HV side 107 and
in parallel in the LV side 109.
[0109] FIG. 9 shows a DC-DC converter system 900 according to an
embodiment of the present invention in which the resonant tank
circuit 111 of each DC-DC converter in the system 900 is of the
CLLC type as explained above. In detail does FIG. 9 show an
interleaving of a plurality of converters 200 as shown in FIG. 2.
In this system 900, the HV sides 107a. . . 107n of the converters
are connected in series between a positive HV terminal and a
negative HV terminal of the system 900. The LV sides 109a. . . 109n
of the converters are connected in parallel to a positive LV
terminal and a negative LV terminal of the system 900.
[0110] FIG. 10 shows a DC-DC converter system 1000 according to an
embodiment of the present invention in which the resonant tank
circuit 111 of each converter in the system 1000 is of the 3LC type
as explained above. In details does FIG. 10 show an interleaving of
a plurality of converters 300 as shown in FIG. 5. In this system
1000, the HV sides 107a. . . 107n of the converters are connected
in series between a positive HV terminal and a negative HV terminal
of the system 1000. The LV sides 109a. . . 109n of the converters
are connected in parallel to a positive LV terminal and a negative
LV terminal of the system 1000.
[0111] Although the examples in FIGS. 9 and 10 showed an
interleaving of the DC-DC converters 200 and 300, further
embodiments also include an interleaving the other DC-DC converters
introduced in this documents (also in the general form of the DC-DC
converter 100).
[0112] Finally, it should be understood that the present invention
is not limited to the embodiments described above, but also relates
to and incorporates all embodiments within the scope of the
appended independent claims.
* * * * *