CN116455229A - Power converter and energy storage system - Google Patents

Power converter and energy storage system Download PDF

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Publication number
CN116455229A
CN116455229A CN202310202141.0A CN202310202141A CN116455229A CN 116455229 A CN116455229 A CN 116455229A CN 202310202141 A CN202310202141 A CN 202310202141A CN 116455229 A CN116455229 A CN 116455229A
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CN
China
Prior art keywords
bridge arm
inductor
midpoint
capacitor
power converter
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Pending
Application number
CN202310202141.0A
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Chinese (zh)
Inventor
陈旭东
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Sungrow Shanghai Co Ltd
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Sungrow Shanghai Co Ltd
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Application filed by Sungrow Shanghai Co Ltd filed Critical Sungrow Shanghai Co Ltd
Priority to CN202310202141.0A priority Critical patent/CN116455229A/en
Publication of CN116455229A publication Critical patent/CN116455229A/en
Pending legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H02M3/33584—Bidirectional converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/217—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M7/219—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only in a bridge configuration
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The application discloses power converter and energy storage system, power converter includes: the first bridge arm and the second bridge arm with input ends connected in parallel also comprise: a first inductor and a first capacitor; the first bridge arm comprises a first switching tube and a third switching tube which are connected in series, and the second bridge arm comprises a second switching tube and a fourth switching tube which are connected in series; the first inductor and the first capacitor are connected in series and then are connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm; and the first capacitor is used for bearing the direct current component between the midpoint of the first bridge arm and the midpoint of the second bridge arm. Because the capacitor has the function of preventing direct current from passing through, direct current components can be applied to two ends of the capacitor, and the voltage at two ends of the inductor is pure alternating current components, so that the phenomenon that positive and negative half cycles of current flowing through the inductor are asymmetric is avoided, namely, direct current bias of the current of the inductor is avoided.

Description

Power converter and energy storage system
Technical Field
The application relates to the technical field, in particular to a power converter and an energy storage system.
Background
At present, in many fields, a direct current/direct current (dc/dc) converter is required, an isolated DCDC converter can be used to avoid interference of electric signals, a resonant isolated DCDC converter exists at present, and in order to transmit electric energy in both forward and reverse directions, namely, a bidirectional resonant isolated DCDC converter, an inductor is arranged between the midpoints of two bridge arms of a primary full-bridge circuit, and the inductor can participate in resonance during reverse energy transmission.
In theory, the time of the two working modes in each period is equal, the positive half cycle and the negative half cycle of the voltage at the two ends of the inductor are completely symmetrical, and the current of the inductor rises and falls in each switching period by taking 0 as the center.
In practice, when component parameter errors and line dissymmetry (for example, there is a difference in routing of a printed circuit board PCB) or there is a difference in driving waveforms (for example, there is an error in output of a driving circuit) of the controller, the voltages at both ends of the inductor may be asymmetric in positive and negative half cycles, so that dc bias is generated, and the current flowing through the inductor is not changed symmetrically about 0. This may lead to a deterioration of the operation performance of the first full-bridge circuit, and in severe cases, may lead to a magnetic saturation phenomenon of the inductor, and eventually the entire DCDC converter fails.
Disclosure of Invention
In view of this, the present application provides a power converter and an energy storage system, which can make the current on the inductor symmetrical in positive and negative half cycles, and avoid the magnetic saturation of the inductor.
The present application provides a power converter comprising: the first bridge arm and the second bridge arm with input ends connected in parallel also comprise: a first inductor and a first capacitor;
the first bridge arm comprises a first switching tube and a third switching tube which are connected in series, and the second bridge arm comprises a second switching tube and a fourth switching tube which are connected in series;
the first inductor and the first capacitor are connected in series and then are connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm; and the first capacitor is used for bearing the direct current component between the midpoint of the first bridge arm and the midpoint of the second bridge arm.
Preferably, the first switching tube and the fourth switching tube have the same switching state, and the second switching tube and the third switching tube have the same switching state; the first switching tube and the second switching tube are complementary in switching state and identical in duty ratio.
Preferably, the power converter is an isolated DCDC power converter, further comprising: a transformer and a secondary circuit;
two ends of a primary winding of the transformer are respectively connected with the midpoint of the first bridge arm and the midpoint of the second bridge arm;
the two ends of the secondary winding of the transformer are respectively connected with the two input ends of the secondary circuit.
Preferably, the secondary side circuit comprises a third bridge arm and a fourth bridge arm with output ends connected in parallel;
the third bridge arm comprises two controllable switching tubes connected in series, and the fourth bridge arm comprises two controllable switching tubes connected in series.
Preferably, the method further comprises: a second inductor;
the second inductor is connected in series with the primary winding and then is connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm.
Preferably, the method further comprises: a second capacitor;
the second inductor, the primary winding and the second capacitor are connected in series and then connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm.
Preferably, the method further comprises: a third inductance;
the third inductor is connected in parallel with two ends of the primary winding of the transformer.
Preferably, the second inductor, the primary winding and the second capacitor form a first LLC resonance when the power converter is transmitting energy in the forward direction;
preferably, the second inductance, the third inductance and the second capacitance form a first LLC resonance when the power converter is transmitting energy in the forward direction.
Preferably, the first inductance, the second inductance and the second capacitance form a second LLC resonance when the power converter is transmitting energy in reverse.
The present application also provides an energy storage system comprising: the first full-bridge circuit, the transformer and the second full-bridge circuit; further comprises: the first inductor, the second inductor, the first capacitor and the second capacitor;
the first inductor and the first capacitor are connected in series between the midpoint of the first bridge arm and the midpoint of the second bridge arm;
the primary winding of the transformer and the second capacitor are connected in series and then connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm;
the first full-bridge circuit is used for connecting the energy storage battery and/or the second full-bridge circuit is used for connecting the energy storage battery.
Preferably, the second inductor, the primary winding and the second capacitor form a first LLC resonance when the first full bridge circuit transfers energy to the second full bridge circuit;
the first inductor, the second inductor, and the second capacitor form a second LLC resonance when the second full bridge circuit transfers energy to the first full bridge circuit.
From this, this application has following beneficial effect:
the application provides a power converter, the first bridge arm and the second bridge arm that the input is connected in parallel together still includes: a first inductor and a first capacitor; the first inductor and the first capacitor are connected in series and then are connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm; the midpoint of the first bridge arm and the midpoint of the second bridge arm are respectively the two output ends of the power converter; and the first capacitor is used for bearing the direct current component between the midpoint of the first bridge arm and the midpoint of the second bridge arm. Because the capacitor has the function of preventing direct current from passing through, direct current components can be applied to two ends of the capacitor, and the voltage at two ends of the inductor is pure alternating current components, so that the phenomenon that positive and negative half cycles of current flowing through the inductor are asymmetric is avoided, namely, direct current bias of the current of the inductor is avoided.
Drawings
Fig. 1 is a schematic diagram of a bidirectional isolation type DCDC converter according to an embodiment of the present application;
fig. 2 is a schematic diagram of a power converter according to an embodiment of the present disclosure;
FIG. 3 is a waveform diagram of a voltage and current provided in an embodiment of the present application;
FIG. 4 is a waveform diagram showing a DC component of the voltage between the midpoints of two legs;
FIG. 5 is a waveform diagram of another voltage between two bridge arm midpoints with a DC component;
fig. 6 is a schematic diagram of another bidirectional isolation DCDC converter according to an embodiment of the present disclosure;
FIG. 7 is a schematic diagram of another power converter according to an embodiment of the present disclosure;
FIG. 8 is a schematic diagram of yet another power converter provided in an embodiment of the present application;
FIG. 9 is a schematic diagram of yet another power converter according to an embodiment of the present disclosure;
FIG. 10 is a schematic diagram of yet another power converter provided in an embodiment of the present application;
FIG. 11 is a schematic diagram of an energy storage system according to an embodiment of the present disclosure;
FIG. 12 is a schematic diagram of another energy storage system provided in an embodiment of the present application;
fig. 13 is a schematic diagram of yet another energy storage system according to an embodiment of the present application.
Detailed Description
In order to enable a person skilled in the art to better understand the technical scheme provided by the embodiments of the present application, an application scenario of the technical scheme provided by the embodiments of the present application is described below with reference to the accompanying drawings.
The embodiment of the application provides a power converter, which can be a DCDC converter, an isolated DCDC converter or a non-isolated DCDC converter. For ease of understanding, the power converter is described below as an isolated DCDC converter, and the isolated DCDC converter may be a bidirectional isolated DCDC converter, and wherein LLC resonance exists, i.e., a resonant isolated DCDC converter. The specific application scene can be in the photovoltaic field, the energy storage field and the optical storage field, for example, the application of the optical storage field in an energy storage converter PCS.
When the bidirectional isolation type DCDC converter is applied to the energy storage field, the bidirectional isolation type DCDC converter can realize the charge and discharge of an energy storage battery, namely, the bidirectional flow of energy.
Referring to fig. 1, the schematic diagram of a bidirectional isolation type DCDC converter according to an embodiment of the present application is shown.
The bidirectional isolation type DCDC converter comprises a first full-bridge circuit, a transformer T and a second full-bridge circuit; further comprises: the first inductance Lm1, the second inductance Lr, and the second capacitance Cr.
The first full-bridge circuit comprises a first bridge arm and a second bridge arm, wherein the input ends (assuming that energy is transmitted from left to right) of the first bridge arm and the second bridge arm are connected in parallel, the first bridge arm comprises a first switching tube Q1 and a third switching tube Q3 which are connected in series, and the second bridge arm comprises a second switching tube Q2 and a fourth switching tube Q4 which are connected in series; it should be appreciated that the common terminal of Q1 and Q3 is the midpoint of the first leg and the common terminal of Q2 and Q4 is the midpoint of the second leg.
The first inductor Lm1 is connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm; the midpoint of the first bridge arm and the midpoint of the second bridge arm are output ends of the power converter;
the switching states of the first switching tube Q1 and the fourth switching tube Q4 are the same, and the switching states of the second switching tube Q2 and the third switching tube Q3 are the same; the switching states of the first switching tube Q1 and the second switching tube Q2 are complementary and the duty ratio is the same. It should be appreciated that Q1 and Q2 switch state complementation means that Q2 is off when Q1 is on; when Q2 is on, Q1 is off. The duty cycles of Q1 and Q2 are the same in order to make the positive half-cycle and the negative half-cycle as symmetrical as possible.
When the first switching tube and the fourth switching tube are turned on, and the second switching tube and the third switching tube are turned off, the voltage at two ends of the inductor is equal to the input voltage; when the second switching tube and the third switching tube are turned on and the first switching tube and the fourth switching tube are turned off, the voltage at two ends of the inductor is equal to the negative input voltage. In theory, the time of the two working modes in each period is equal, the positive half cycle and the negative half cycle of the voltage at the two ends of the inductor are completely symmetrical, and the current of the inductor rises and falls in each switching period by taking 0 as the center.
The second full-bridge circuit comprises a third bridge arm and a fourth bridge arm, the output ends (assuming that energy is transmitted from left to right) of the third bridge arm and the fourth bridge arm are connected in parallel, the third bridge arm comprises a fifth switching tube Q5 and a seventh switching tube Q7 which are connected in series, and the fourth bridge arm comprises a sixth switching tube Q6 and an eighth switching tube Q8 which are connected in series; it should be appreciated that the common terminal of Q5 and Q7 is the midpoint of the third leg and the common terminal of Q6 and Q8 is the midpoint of the fourth leg.
Because the first full-bridge circuit and the second full-bridge circuit both comprise controllable switching tubes, energy can flow bidirectionally, namely, direct-current voltage U1 can be converted into direct-current voltage U2 for output, and direct-current voltage U2 can be converted into direct-current voltage U1 for output.
Lm1 does not participate in the main power resonance when energy is transferred from the first full-bridge circuit to the second full-bridge circuit, lm1 only participates in the main power resonance when energy is transferred from the second full-bridge circuit to the first full-bridge circuit.
The following mainly describes the transfer of energy from the first full-bridge circuit in the direction of the second full-bridge circuit.
When Q1 and Q4 are on and Q2 and Q3 are off, the voltage across Lm1 is equal to U1; when Q2 and Q3 are on, and Q1 and Q4 are off, the voltage across Lm1 is equal to-U1. In theory, the time of the two working modes in each period is equal, the positive half cycle and the negative half cycle of the voltage at the two ends of Lm1 are completely symmetrical, and the current of Lm1 takes 0 as the center, and rises and falls in each switching period. However, in reality, when component parameter errors and line asymmetry (for example, there is a difference in PCB routing) or there is a difference in driving waveforms (for example, there is an error in driving circuit output) of the controller, the positive and negative half cycles of the voltages at both ends of Lm1 may be asymmetric, so that dc bias is generated, and the current flowing through Lm1 is not changed symmetrically about 0. This may lead to a deterioration of the operation performance of the first full-bridge circuit, and in severe cases, may lead to a phenomenon of magnetic saturation of Lm1, eventually disabling the entire DCDC converter.
In order to solve the problem of magnetic saturation of the inductor, a capacitor is added before the middle points of two bridge arms, so that the capacitor and the inductor are connected between the middle points of the two bridge arms after being connected in series, when the positive half cycle and the negative half cycle of the voltage at the two ends of the inductor are asymmetric due to the error in the actual product, and the positive half cycle and the negative half cycle of the current are not completely symmetric, direct current components can be completely applied to the two ends of the capacitor, and cannot be applied to the two ends of the inductor, therefore, the direct current components cannot be generated by the current of the inductor, further, the magnetic saturation of the inductor cannot occur, and the whole power converter cannot work normally due to the magnetic saturation of the inductor.
The power converter provided by the embodiment of the application is not limited to a bidirectional DCDC converter, an isolated DCDC converter and a resonance type DCDC converter, and only a full-bridge circuit is included, and an inductor is connected between the midpoints of two bridge arms of the full-bridge circuit.
In order to make the above objects, features and advantages of the present application more comprehensible, embodiments accompanied with figures and detailed description are described in further detail below.
Referring to fig. 2, a schematic diagram of a power converter according to an embodiment of the present application is shown.
The power converter provided by the embodiment of the application comprises: the first bridge arm and the second bridge arm with input ends connected in parallel also comprise: a first inductance Lm1 and a first capacitance Cm1;
the first bridge arm comprises a first switching tube Q1 and a third switching tube Q3 which are connected in series, and the second bridge arm comprises a second switching tube Q2 and a fourth switching tube Q4 which are connected in series.
The switching states of Q1 and Q4 are the same, the switching states of Q2 and Q3 are the same, the switching states of Q1 and Q2 are complementary, and ideally, if dead time is not considered, the duty ratio of Q1 and Q2 is 50%, namely in a switching period, the first half period, Q1 is on, and Q2 is off; in the latter half of the cycle, Q1 is off and Q2 is on. If the errors of the actual devices and lines are not taken into account, ideally the positive half-cycle and the negative half-cycle of the current flowing through Lm1 are completely symmetrical, and no dc component is present. However, in practice, there is an error, which causes a dc component between the two legs, and a dc offset is generated.
The first inductor Lm1 and the first capacitor Cm1 are connected in series and then connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm; the midpoint of the first bridge arm and the midpoint of the second bridge arm are respectively the output two ends of the power converter, namely a positive output end and a negative output end; the first capacitor Cm1 is used for bearing a direct current component between the midpoint of the first bridge arm and the midpoint of the second bridge arm.
Because the capacitor has the function of preventing direct current from passing through, direct current components can be applied to two ends of the capacitor, and the voltage at two ends of the inductor is pure alternating current components, so that the phenomenon that positive and negative half cycles of current flowing through the inductor are asymmetric is avoided, namely, direct current bias of the current of the inductor is avoided.
Referring to fig. 3, a waveform diagram of a voltage and a current is provided in an embodiment of the present application.
Vb in fig. 3 represents the voltage between the two bridge arm midpoints, im1 represents the current of the inductor Lm1, and Vcm1 represents the voltage across the inductor.
As can be seen from fig. 3, the current of the inductor is ideally completely symmetrical in positive and negative half cycles, and the duration of the positive level and the duration of the negative level of Vb are the same, i.e. the duty cycle is 50%.
According to the technical scheme provided by the embodiment of the application, although direct-current components exist in the voltage between the middle points of the two bridge arms, the current of the inductor is symmetrical in positive and negative half cycles due to the existence of the capacitor.
Referring to fig. 4, a waveform diagram is shown where there is a dc component of the voltage between the midpoints of two legs.
As can be seen from fig. 4, vb has a center point above 0, although it has a duty cycle of 50%. The center point of Vcm1 is also above 0. However, the dc component in Vb is all applied to the first capacitor Cm1, and there is no dc bias in the current of the inductor.
Referring to fig. 5, another waveform is shown where there is a dc component of the voltage between the midpoints of two legs.
As can be seen from fig. 5, the duty cycle of Vb is greater than 50%, i.e. the duration of the high level is greater than the duration of the low level. The center point of Vcm1 is also above 0. However, the dc component in Vb is all applied to the first capacitor Cm1, and there is no dc bias in the current of the inductor.
The implementation when the power converter is a bi-directional isolated DCDC converter is described below with reference to the accompanying drawings.
Referring to fig. 6, a schematic diagram of another bidirectional isolated DCDC converter according to an embodiment of the present application is shown.
As can be seen by comparing fig. 6 and fig. 1, a first capacitance Cm1 is added between the midpoint of the first leg and the midpoint of the second leg. The rest of the architecture is the same, and the energy can realize bidirectional flow.
The bidirectional isolated DCDC converter further includes: a transformer T and a secondary circuit;
two ends of a primary winding of the transformer are respectively connected with a midpoint (a common end of Q1 and Q3) of the first bridge arm and a midpoint (a common end of Q2 and Q4) of the second bridge arm;
the two ends of the secondary winding of the transformer are respectively connected with the two input ends of the secondary circuit.
The secondary side circuit comprises a third bridge arm and a fourth bridge arm, wherein the output ends of the third bridge arm and the fourth bridge arm are connected in parallel;
the third bridge arm comprises two controllable switching tubes in series, namely a fifth switching tube Q5 and a seventh switching tube Q7, and the fourth bridge arm comprises two controllable switching tubes in series, namely a sixth switching tube Q6 and an eighth switching tube Q8.
The bidirectional isolated DCDC converter further includes: a second inductance Lr; the second inductor Lr is connected in series with the primary winding and then connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm.
The bidirectional isolated DCDC converter further includes: a second capacitor Cr;
the second inductor Lr, the primary winding and the second capacitor Cr are connected in series and then connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm.
When the bidirectional isolation type DCDC converter transmits energy in the forward direction, the second inductor Lr, the primary winding and the second capacitor Cr form a first LLC resonance.
When the bidirectional isolation type DCDC converter reversely transmits energy, the first inductor Lm1, the second inductor Lr and the second capacitor Cr form second LLC resonance.
When power is transmitted from right to left, lm1 and Cm1 participate in main power resonance together, and it is required to ensure that the performance of the circuit shown in fig. 6 is substantially unchanged from that of the circuit shown in fig. 1. The impedance of the branch between the midpoints of the two legs in the circuit shown in fig. 1 is:
Z m1 ＝jωL m1
the impedance of the branch in the circuit of FIG. 6 is
Theoretically only let Z m1 ＝Z′ m1 I.e.It is possible to realize a circuit with substantially unchanged functions. In actual design, values of Lm1 and Cm1 in the new design are flexibly adjusted according to the original design, so that the impedance of the branch is close to that of fig. 1.
The bidirectional isolation type DCDC converter provided by the embodiment of the application not only can realize forward transmission of energy, but also can realize reverse transmission of energy, and can realize LLC resonance during forward transmission, and can also realize LLC resonance during reverse transmission. In addition, during forward transmission, due to the existence of the Cm1, the direct current component can be applied to two ends of the Cm1, and the inductance cannot be influenced, so that the current on the inductance Lm1 is symmetrical about a positive half cycle and a negative half cycle, and the phenomenon of magnetic saturation of the inductance is avoided.
The third inductor in fig. 6 may be an equivalent inductor of the transformer or an additional inductor. It should be appreciated that when energy is transferred from left to right, the inductance involved in the resonance may be, in addition to the primary winding of the transformer, a third inductance, i.e. the second inductance, the third inductance and the second capacitance, forming an LLC resonance.
Referring to fig. 7, a schematic diagram of another power converter according to an embodiment of the present application is shown.
The resonant isolation type bidirectional DCDC converter is described above, and in addition, the technical scheme provided by the embodiment of the application is also applicable to a common isolation type DCDC converter, and the converter shown in fig. 8 is one implementation manner.
Referring to fig. 8, a schematic diagram of yet another power converter according to an embodiment of the present application is provided.
The midpoint of the first bridge arm is connected with the midpoint of the second bridge arm through a second inductor Lr and a primary winding which are connected in series. The midpoint of the first bridge arm is connected with the midpoint of the second bridge arm through a first inductor Lm1 and a first capacitor Cm1 which are connected in series.
Referring to fig. 9, a schematic diagram of yet another power converter according to an embodiment of the present application is provided.
Fig. 9 shows another conventional isolated DCDC converter in which the midpoint of the first leg is connected to the midpoint of the second leg through the primary winding. The midpoint of the first bridge arm is connected with the midpoint of the second bridge arm through a first inductor Lm1 and a first capacitor Cm1 which are connected in series.
In addition, it should be understood that, corresponding to the isolated DCDC converter shown in fig. 7, the form shown in fig. 10 may be further adopted, the second inductor shown in fig. 7 is omitted, the second inductor shown in fig. 7 is integrated with the primary winding of the transformer, the second inductor is omitted, and the midpoint of the first bridge arm is connected to the midpoint of the second bridge arm through the primary winding and the second capacitor Cr connected in series, as shown in fig. 10.
Based on the power converter provided in the above embodiments, the embodiments of the present application further provide an energy storage system, which is described in detail below with reference to the accompanying drawings.
Referring to fig. 11, a schematic diagram of an energy storage system according to an embodiment of the present application is provided.
The energy storage system is used for realizing charging and discharging of the energy storage battery and can realize bidirectional flow of energy.
The energy storage system includes: the first full-bridge circuit, the transformer and the second full-bridge circuit; further comprises: a first inductance Lm1, a second inductance Lr, a first capacitance Cm1, and a second capacitance Cr;
a first end of the first full-bridge circuit is used for connecting the energy storage battery BAT, as shown in fig. 11;
alternatively, the first end of the second full bridge circuit is used to connect the energy storage battery BAT, as shown in fig. 12;
or, the first end of the first full-bridge circuit and the first end of the second full-bridge circuit are both connected with the energy storage battery, as shown in figure 13, the first end of the first full-bridge circuit is connected with the energy storage battery BAT1, and the second end of the second full-bridge circuit is connected with the energy storage battery BAT2. It should be appreciated that energy between the energy storage battery BAT1 and the energy storage battery BAT2 may be transferred to each other, for example, the energy storage battery BAT1 charges the energy storage battery BAT2, or the energy storage battery BAT2 charges the energy storage battery BAT 1.
The following is described in detail with reference to fig. 11.
The first inductor Lm1 and the first capacitor are connected in series between the midpoint of the first bridge arm and the midpoint of the second bridge arm;
the second inductor Lr, a primary winding of the transformer and the second capacitor Cr are connected in series and then are connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm;
when the energy storage battery BAT discharges, the first full-bridge circuit transmits energy to the second full-bridge circuit; when the energy storage battery is charged, the second full-bridge circuit transmits energy to the first full-bridge circuit.
In the energy storage system provided by the embodiment of the application, after the first inductor Lm1 and the first capacitor Cm1 are connected in series, the first inductor Lm1 and the first capacitor Cm1 are connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm; the midpoint of the first bridge arm and the midpoint of the second bridge arm are respectively the output two ends of the power converter, namely a positive output end and a negative output end; the first capacitor Cm1 is used for bearing a direct current component between the midpoint of the first bridge arm and the midpoint of the second bridge arm.
Because the capacitor has the function of preventing direct current from passing through, direct current components can be applied to two ends of the capacitor, and the voltage at two ends of the inductor is pure alternating current components, so that the phenomenon that positive and negative half cycles of current flowing through the inductor are asymmetric is avoided, namely, direct current bias of the current of the inductor is avoided.
In addition, in order to reduce power consumption and improve the discharge efficiency of the energy storage battery, when the energy storage battery discharges, the second inductor Lr, the primary winding and the second capacitor Cr form first LLC resonance;
in order to reduce power consumption and improve charging efficiency of the energy storage battery, when the energy storage battery is charged, the first inductor Lm1, the second inductor and the second capacitor form second LLC resonance.
The converter provided by the embodiment of the application not only can be applied to an energy storage system, but also can be applied to a photovoltaic system, a Yu Guangchu system and other DCDC conversion occasions, and is not particularly limited herein.
It should be noted that, in the present specification, each embodiment is described in a progressive manner, each embodiment is mainly described and is different from other embodiments, and the same similar parts among the embodiments are mutually referred. For the system or device disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the relevant points refer to the description of the method section.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (12)

1. A power converter, comprising: the first bridge arm and the second bridge arm with input ends connected in parallel also comprise: a first inductor and a first capacitor;
the first bridge arm comprises a first switching tube and a third switching tube which are connected in series, and the second bridge arm comprises a second switching tube and a fourth switching tube which are connected in series;
the first inductor and the first capacitor are connected in series and then connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm; the first capacitor is used for bearing direct current components between the middle point of the first bridge arm and the middle point of the second bridge arm.
2. The power converter of claim 1, wherein the first switching tube and the fourth switching tube are in the same switching state, and the second switching tube and the third switching tube are in the same switching state; the first switching tube and the second switching tube are complementary in switching state and identical in duty ratio.
3. The power converter of claim 2, wherein the power converter is an isolated DCDC power converter, further comprising: a transformer and a secondary circuit;
two ends of a primary winding of the transformer are respectively connected with the midpoint of the first bridge arm and the midpoint of the second bridge arm;
and two ends of a secondary winding of the transformer are respectively connected with two input ends of the secondary circuit.
4. The power converter of claim 3, wherein the secondary circuit comprises a third leg and a fourth leg with outputs connected in parallel;
the third bridge arm comprises two controllable switching tubes connected in series, and the fourth bridge arm comprises two controllable switching tubes connected in series.
5. The power converter of claim 3 or 4, further comprising: a second inductor;
and the second inductor is connected in series with the primary winding and then is connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm.
6. The power converter of claim 5, further comprising: a second capacitor;
the second inductor, the primary winding and the second capacitor are connected in series and then connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm.
7. The power converter of claim 6, further comprising: a third inductance;
the third inductor is connected in parallel with two ends of a primary winding of the transformer.
8. The power converter of claim 7, wherein the second inductor, the primary winding, and the second capacitor form a first LLC resonance when the power converter is transmitting energy in a forward direction.
9. The power converter of claim 7, wherein the second inductance, the third inductance, and the second capacitance form a first LLC resonance when the power converter is transmitting energy in a forward direction.
10. A power converter according to any of claims 6-8, characterized in that the first inductance, the second inductance and the second capacitance form a second LLC resonance when the power converter is transmitting energy in reverse.
11. An energy storage system, comprising: the first full-bridge circuit, the transformer and the second full-bridge circuit; further comprises: the first inductor, the second inductor, the first capacitor and the second capacitor;
the first inductor and the first capacitor are connected in series between the midpoint of the first bridge arm and the midpoint of the second bridge arm;
the second inductor, the primary winding of the transformer and the second capacitor are connected in series and then connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm;
the first full-bridge circuit is used for connecting an energy storage battery and/or the second full-bridge circuit is used for connecting the energy storage battery.
12. The system of claim 11, wherein the second inductor, the primary winding, and the second capacitor form a first LLC resonance when the first full bridge circuit transfers energy to the second full bridge circuit;
when the second full-bridge circuit transmits energy to the first full-bridge circuit, the first inductor, the second inductor and the second capacitor form second LLC resonance.
CN202310202141.0A 2023-03-03 2023-03-03 Power converter and energy storage system Pending CN116455229A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202310202141.0A CN116455229A (en) 2023-03-03 2023-03-03 Power converter and energy storage system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202310202141.0A CN116455229A (en) 2023-03-03 2023-03-03 Power converter and energy storage system

Publications (1)

Publication Number Publication Date
CN116455229A true CN116455229A (en) 2023-07-18

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Family Applications (1)

Application Number Title Priority Date Filing Date
CN202310202141.0A Pending CN116455229A (en) 2023-03-03 2023-03-03 Power converter and energy storage system

Country Status (1)

Country Link
CN (1) CN116455229A (en)

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