Power supply current balancing device and control method thereof

Abstract

The present application discloses a control method for power supply current balancing, including: controlling a first DC / DC converter and a second DC / DC converter to operate in current mode; obtaining a first feedback voltage U1 and a first feedback current I1 of a first DC / DC feedback circuit, and a second feedback voltage U2 and a second feedback current I2 of a second DC / DC feedback circuit; calculating a virtual impedance Z based on the first feedback voltage U1, the first feedback current I1, the second feedback voltage U2, and the second feedback current I2, where Z = U1 / I1-U2 / I2; calling the virtual impedance Z, compensating for the feedback voltage, performing a PID control operation, obtaining a PID control variable, and using the PID control variable to adjust the actual voltage output of the first DC / DC feedback circuit and the second DC / DC feedback circuit. A virtual impedance is added to the DC / DC feedback circuit, the virtual impedance Z is called, the feedback voltage is compensated, a PID control operation is performed, and the PID control variable is obtained to adjust the actual voltage output of the DC / DC feedback circuit to achieve current balancing control.

Description

Technical Field

[0001] The present application relates to the technical field of power supply systems, and in particular to a power supply current balancing device and a control method thereof. Background Art

[0002] Parallel connection of distributed power supply systems can realize modular and standardized system design of power supply, which can improve system reliability. However, it also requires that current equalization measures be taken between parallel power supplies to ensure that current stress and thermal stress are evenly distributed between parallel power supply modules.

[0003] Existing current-sharing measures between power supplies include active balancing, which involves connecting two DC / DC converters in parallel. DCDC1 is the master DC-DC converter, operating in voltage control mode and controlling its voltage output. DCDC2 is the slave DC-DC converter, operating in current control mode. After learning DCDC1's current through communication, it uses a compensator to adjust its own current setting, I*=(I1+I2) / 2, so that the current flowing through DCDC2 is half of the total load, thus achieving current balancing. Active balancing requires communication between the two power modules, DCDC1 and DCDC2, but this communication has a certain delay, affecting the timeliness of control.

[0004] Another method for current balancing between power supplies involves connecting a droop resistor in series with the circuit. This resistor, when the current increases, decreases the output voltage. As the voltage decreases, the load capacity of the power supplies decreases, thus achieving dynamic balancing. However, this method has poor balancing capabilities. Summary of the Invention

[0005] The present application provides a power supply current balancing device and a control method thereof to solve the problem of how to achieve effective current sharing between power supplies.

[0006] In order to solve the above technical problems, the present application provides a control method for power supply current balancing, comprising:

[0007] Controlling the first DC / DC converter and the second DC / DC converter to operate in current mode, wherein the first DC / DC converter and the second DC / DC converter are connected in parallel;

[0008] Obtaining a first feedback voltage U1 and a first feedback current I1 of a first DC / DC feedback circuit and a second feedback voltage U2 and a second feedback current I2 of a second DC / DC feedback circuit;

[0009] Make the first feedback current I1 equal to the second feedback current I2, and calculate the virtual impedance Z, Z = U1 / I1-U2 / I2;

[0010] The virtual impedance Z is called to compensate the output voltage for performing a PID control operation to obtain a PID control variable. The PID control variable is used to control a first PWM modulation module of the first DC / DC feedback circuit and a second PWM modulation module of the second DC / DC feedback circuit. The first PWM modulation module adjusts the actual voltage output of the first DC / DC feedback circuit, and the second PWM modulation module adjusts the actual voltage output of the second DC / DC feedback circuit.

[0011] Furthermore, a first virtual impedance Z / 2 is connected to the first DC / DC feedback circuit, and a second virtual impedance Z / 2 is connected to the second DC / DC feedback circuit. The impedance values ​​of the first virtual impedance Z / 2 and the second virtual impedance Z / 2 are both half of the virtual impedance Z.

[0012] Furthermore, the first PWM modulation module controls the PWM duty cycle of the first DC / DC feedback circuit, and the second PWM modulation module controls the PWM duty cycle of the second DC / DC feedback circuit.

[0013] The present invention provides a power supply current balancing device, comprising:

[0014] a control module, controlling the first DC / DC converter and the second DC / DC converter to operate in a current mode, wherein the first DC / DC converter and the second DC / DC converter are connected in parallel;

[0015] An acquisition module, configured to acquire a first feedback voltage U1 and a first feedback current I1 of a first DC / DC feedback circuit and a second feedback voltage U2 and a second feedback current I2 of a second DC / DC feedback circuit;

[0016] a calculation module, calculating a virtual impedance Z according to the first feedback voltage U1, the first feedback current I1, the second feedback voltage U2, and the second feedback current I2, where Z=U1 / I1-U2 / I2;

[0017] The calling and control module calls the virtual impedance Z, compensates the feedback voltage, performs a PID control operation, obtains a PID control variable, and uses the PID control variable to control a first PWM modulation module of the first DC / DC feedback circuit and a second PWM modulation module of the second DC / DC feedback circuit, wherein the first PWM modulation module adjusts the actual voltage output of the first DC / DC feedback circuit, and the second PWM modulation module adjusts the actual voltage output of the second DC / DC feedback circuit.

[0018] Furthermore, a first virtual impedance Z / 2 is connected to the first DC / DC feedback circuit, and a second virtual impedance Z / 2 is connected to the second DC / DC feedback circuit. The impedance values ​​of the first virtual impedance Z / 2 and the second virtual impedance Z / 2 are both half of the virtual impedance Z.

[0019] Furthermore, one end of the first virtual impedance Z / 2 is connected to the first current transformer, and the other end is connected to the signal input end of the first DC / DC feedback circuit; one end of the second virtual impedance Z / 2 is connected to the second current transformer, and the other end is connected to the signal input end of the second DC / DC feedback circuit.

[0020] Furthermore, the power current balancing device further includes a first adding module configured to input the first virtual impedance Z / 2 and the first feedback voltage U1 , and output the first net feedback voltage U1_Fed and the first reference voltage Uref1 as inputs of the compensator after operation.

[0021] Furthermore, the compensator includes a voltage compensator and a current compensator. The first net feedback voltage U1_Fed and the first reference voltage Uref1 are calculated and then pass through the voltage compensator and the current compensator in sequence. The output signals are transmitted to the first PWM modulation module.

[0022] Furthermore, the power current balancing device further includes a second adding module for inputting the second virtual impedance Z / 2 and the second feedback voltage U2, and outputting the second net feedback voltage U2_Fed and the second reference voltage Uref2 as inputs of the compensator after operation.

[0023] Furthermore, the compensator includes a voltage compensator and a current compensator. The second net feedback voltage U2_Fed and the second reference voltage Uref2 are calculated and successively pass through the voltage compensator and the current compensator, and the output signals are transmitted to the second PWM modulation module.

[0024] In order to solve the above technical problems, the present invention further provides an electric vehicle, comprising any one of the power supply current balancing devices described above.

[0025] The technical solution of this application has at least the following advantages:

[0026] A virtual impedance is added to the DCDC feedback circuit, called the virtual impedance Z, and the feedback voltage is compensated for to perform PID control operations. The PID control variable is obtained, and the actual voltage output of the DC / DC feedback circuit is adjusted to achieve current sharing control. The power supply current balancing control method provided by the present invention does not require the other party's current information to be obtained through communication, nor does it require the use of external droop resistors to achieve current sharing. Current sharing control can be achieved by simply introducing a virtual impedance variable.

[0027] The present application also provides an electric vehicle having the same beneficial effects as the above-mentioned power supply current balancing device. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0029] Figure 1 A schematic diagram of the flow structure of a method for controlling power supply current balancing provided by an embodiment of the present invention;

[0030] Figure 2 A schematic diagram of the structure of a power supply current balancing device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The following is a clear and complete description of the technical solutions in this application in conjunction with the accompanying drawings. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0032] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of this application and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0033] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal connections between two components; they can refer to wireless connections or wired connections. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0034] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0035] Figure 1 This is a flow chart of a method for controlling power current balancing according to an embodiment of the present invention. Figure 1 The present invention provides a method for controlling power supply current balancing, comprising:

[0036] S11, controlling the first DC / DC converter and the second DC / DC converter to operate in current mode, with the first DC / DC converter and the second DC / DC converter connected in parallel;

[0037] S12, obtaining a first feedback voltage U1 and a first feedback current I1 of the first DC / DC feedback circuit and a second feedback voltage U2 and a second feedback current I2 of the second DC / DC feedback circuit;

[0038] S13, making the first feedback current I1 equal to the second feedback current I2, and calculating the virtual impedance Z, Z = U1 / I1-U2 / I2;

[0039] S14. Calling the virtual impedance Z to compensate the feedback voltage and perform a PID control operation to obtain a PID control variable. Using the PID control variable, control a first PWM modulation module of the first DC / DC feedback circuit and a second PWM modulation module of the second DC / DC feedback circuit. The first PWM modulation module adjusts the actual voltage output of the first DC / DC feedback circuit, and the second PWM modulation module adjusts the actual voltage output of the second DC / DC feedback circuit.

[0040] The main reason for the imbalance between the first and second DC / DC converters is inconsistent line losses on the connecting lines. In this embodiment of the present invention, the line loss resistor connected to the first DC / DC feedback circuit is Z1, and the line loss resistor connected to the second DC / DC feedback circuit is Z2. Assuming that Z1>Z2, a virtual resistor Z is introduced to prevent the resistance of the connecting lines from affecting the balance.

[0041] Z=Z1-Z2, then Z1-Z / 2=Z2+Z / 2;

[0042] U*=U1-I1*(Z1-Z / 2)

[0043] U*=U2-I2*(Z2+Z / 2)

[0044] Since U* is the same point, U1 and U2 are the first feedback voltage and the second feedback voltage, which are equal to the reference voltage, Z2+Z / 2=Z1-Z / 2

[0045] Therefore, U1=U2, I1=I2 to achieve current sharing.

[0046] Also available:

[0047] U*=(U1+I1*Z / 2)-I1*Z1

[0048] U*=(U2–I2*Z / 2)-I2*Z1

[0049] So we hope that the reference voltage

[0050] Uref 1=U1+I1*Z / 2

[0051] Uref 2=U2-I2*Z / 2

[0052] Keep the reference voltage unchanged and let the feedback voltage change

[0053] U1_Fed=U1-I1*Z / 2

[0054] U2_Fed=U2+I2*Z / 2

[0055] According to the above analysis, we can get

[0056] Z=(Z1–Z2)=(U* / I2–U* / I1)+(U1 / I1–U2 / I2)

[0057] Make the power supply work in current control mode, and make the current reference values ​​of the two power supplies equal, and obtain Z = U1 / I1–U2 / I2.

[0058] The calculated virtual resistance Z is stored in an EEPROM (Electrically Erasable Programmable read only memory) so that the virtual resistance Z can be called to perform PID control calculation.

[0059] In an embodiment of the present invention, a first virtual impedance Z / 2 is connected to the first DC / DC feedback circuit, and a second virtual impedance Z / 2 is connected to the second DC / DC feedback circuit. The impedance values ​​of the first virtual impedance Z / 2 and the second virtual impedance Z / 2 are both half of the virtual impedance Z.

[0060] The PID (Proportional Integral Differential) performs control calculation to obtain a PID control variable, and the PID control variable is used to adjust the PWM duty cycle of the first DC / DC feedback circuit and the PWM (Pulse Width Modulation) duty cycle of the second DC / DC feedback circuit. The voltage outputs of the first and second DC / DC converters are controlled according to the PWM duty cycle, thereby achieving current sharing control for the entire parallel power supply. That is, if the load capacity of the first DC / DC feedback circuit is smaller than that of the second DC / DC feedback circuit, the voltage output of the first DC / DC feedback circuit is less than the voltage output of the second DC / DC feedback circuit. In order to make the voltage outputs of the two circuits converge and achieve current sharing control for the parallel power supplies, the feedback voltage of the first DC / DC feedback circuit is reduced. Since the reference voltages of the first and second DC / DC feedback circuits are the same, the duty cycle of the first DC / DC feedback circuit is increased through PID regulation. Furthermore, as the duty cycle of the first DC / DC feedback circuit increases, the voltage output of the first DC / DC feedback circuit increases, ultimately making the voltage output of the first DC / DC feedback circuit equal to the voltage output of the second DC / DC feedback circuit. Therefore, the current of the first DC / DC feedback circuit is equal to the current of the second DC / DC feedback circuit, thereby achieving current sharing control for the entire parallel power supply.

[0061] Figure 2 This is a schematic diagram of the structure of the power supply current balancing device provided by an embodiment of the present invention. Figure 2 The present invention provides a power supply current balancing device, comprising:

[0062] A control module controls the first DC / DC converter 21 and the second DC / DC converter 22 to operate in a current mode, wherein the first DC / DC converter 21 and the second DC / DC converter 22 are connected in parallel;

[0063] An acquisition module, which acquires a first feedback voltage U1 and a first feedback current I1 of the first DC / DC feedback circuit 23 and a second feedback voltage U2 and a second feedback current I2 of the second DC / DC feedback circuit 24;

[0064] a calculation module, calculating a virtual impedance Z according to the first feedback voltage U1, the first feedback current I1, the second feedback voltage U2, and the second feedback current I2, where Z=U1 / I1-U2 / I2;

[0065] The calling and control module calls the virtual impedance Z, compensates the feedback voltage, performs a PID control operation, obtains a PID control variable, and uses the PID control variable to control a first PWM modulation module of the first DC / DC feedback circuit and a second PWM modulation module of the second DC / DC feedback circuit, wherein the first PWM modulation module adjusts the actual voltage output of the first DC / DC feedback circuit, and the second PWM modulation module adjusts the actual voltage output of the second DC / DC feedback circuit.

[0066] In an embodiment of the present invention, the virtual impedance Z is connected to the first DC / DC feedback circuit and the second DC / DC feedback circuit in a half ratio, that is, the first virtual impedance Z / 2 is connected to the first DC / DC feedback circuit, and the second virtual impedance Z / 2 is connected to the second DC / DC feedback circuit. The impedance values ​​of the first virtual impedance Z / 2 and the second virtual impedance Z / 2 are both half of the virtual impedance Z.

[0067] The input end of the power supply is a 48V battery pack, which provides power to the system. It is converted to 12V through a DC / DC converter, and the 12V end provides power to the load.

[0068] V_Comp is the voltage compensator, the purpose of which is to make the reference voltage equal to the given voltage, that is, Uref = U_Fed;

[0069] I_Comp is a current compensator, the purpose of which is to make the reference current equal to the feedback current, that is, I*=I1 or I*=I2.

[0070] In the embodiment of the present invention, one end of the first virtual impedance Z / 2 is connected to the first current transformer 25, and the other end is connected to the signal input end of the first DC / DC feedback circuit 23; one end of the second virtual impedance Z / 2 is connected to the second current transformer 26, and the other end is connected to the signal input end of the second DC / DC feedback circuit 24.

[0071] The power supply current balancing device also includes a first adding module, which inputs a first virtual impedance Z / 2 and a first feedback voltage U1. The output first net feedback voltage U1_Fed and a first reference voltage Uref1 are then calculated and used as inputs to a compensator. The compensator includes a voltage compensator and a current compensator. The first net feedback voltage U1_Fed and the first reference voltage Uref1 are calculated and passed through the voltage compensator and the current compensator, respectively, before the output signals are transmitted to the first PWM modulation module.

[0072] The power supply current balancing device further includes a second addition operation module, which is used to input the second virtual impedance Z / 2 and the second feedback voltage U2, and the output second net feedback voltage U2_Fed and the second reference voltage Uref2 are used as the input of the compensator after calculation. The compensator includes a voltage compensator and a current compensator. The second net feedback voltage U2_Fed and the second reference voltage Uref2 are calculated and then pass through the voltage compensator and the current compensator in sequence, and the output signal is transmitted to the second PWM modulation module.

[0073] The duty cycles of the first PWM modulation module and the second PWM modulation module are controlled by using the PID algorithm. The PWM duty cycle controls the voltage output of the first DC / DC converter and the second DC / DC converter, so as to achieve the current sharing control of the entire parallel power supply.

[0074] Assuming that the value of Z is positive, according to the circuit characteristics, the feedback circuit with the larger output voltage has more load.

[0075] When I1 > I2, then U1 > U2.

[0076] Then there will be 1: (U1 - I1*Z / 2) > (U2 + I2*Z / 2)

[0077] Since the reference values are the same, but the feedback value of U1 is greater than that of U2, the output of U1 decreases with the adjustment of the voltage compensator. Similarly, the output of U2 will gradually increase with the adjustment until the current dynamic balance is achieved, that is

[0078] (U1 - I1*Z / 2) = (U2 + I2*Z / 2)

[0079] Then there will be 2: (U1 - I1*Z / 2) < (U2 + I2*Z / 2)

[0080] Then (U1 - U2) < (I2 - I1)*Z / 2

[0081] Since Z is positive, this situation does not hold.

[0082] When I1 < I2, then U1 < U2.

[0083] Then (U1 - I1*Z / ) / 2 < (U2 + I2*Z / 2)

[0084] Since the reference values are the same, but the feedback value of U1 is less than that of U2, the output of U1 increases with the adjustment of the voltage compensator. Similarly, the output of U2 will gradually decrease with the adjustment until the current dynamic balance is achieved, that is

[0085] (U1-I *Z / 2)=(U2 + I2*Z / 2)

[0086] According to the above analysis, the voltage eventually reaches a dynamic balance, that is, (U1-I1*Z / 2)=(U2+I2*Z / 2)

[0087] Then U1–U*-I1*Z / 2=U2–U*+I2*Z / 2

[0088] Then I1*Z1–I1*Z / 2=I2*Z2+I2*Z / 2

[0089] Then I1*(Z1–Z / 2)=I2*(Z2+Z / 2)

[0090] So at this time I1=I2.

[0091] In order to solve the above technical problems, the present invention also provides an electric vehicle, comprising any one of the power supply current balancing devices described above.

[0092] For an introduction to the electric vehicle provided by the present invention, please refer to the above embodiments, and the present invention will not be described in detail here.

[0093] In addition, the present invention also provides a computer device, which includes a memory and a processor. The memory can be used to store a computer program, and the processor runs the computer program to enable the computer device to execute the above method or the functions of each module in the power parallel connection device.

[0094] The memory may include a program storage area and a data storage area. The program storage area may store an operating system, at least one application required for a function (such as a sound playback function, an image playback function, etc.), etc. The data storage area may store data created based on the use of the mobile terminal (such as audio data, a phone book, etc.), etc. In addition, the memory may include a high-speed random access memory and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other volatile solid-state storage device.

[0095] This embodiment also provides a computer storage medium for storing a computer program used in the above-mentioned computer device.

[0096] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architectures, functions, and operations of the devices, methods, and computer program products according to the multiple embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment, or a portion of code, and the module, program segment, or a portion of code contains one or more executable instructions for implementing the specified logical functions. It should also be noted that in some alternative implementations, the functions marked in the boxes can also occur in an order different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, as well as the combination of boxes in the block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified functions or actions, or can be implemented using a combination of dedicated hardware and computer instructions.

[0097] In addition, the various functional modules in the various embodiments of the present application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0098] If the function is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a number of instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the various embodiments of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, and other media that can store program codes.

[0099] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of this application.

Claims

1. A method for controlling power supply current balancing, characterized in that: include: Controlling the first DC / DC converter and the second DC / DC converter to operate in current mode, wherein the first DC / DC converter and the second DC / DC converter are connected in parallel; Obtaining a first feedback voltage U1 and a first feedback current I1 of a first DC / DC feedback circuit and a second feedback voltage U2 and a second feedback current I2 of a second DC / DC feedback circuit; Make the first feedback current I1 equal to the second feedback current I2, and calculate the virtual impedance Z, Z = U1 / I1-U2 / I2; The virtual impedance Z is called, the feedback voltage is compensated, a PID control operation is performed, and a PID control variable is obtained. The PID control variable is used to control a first PWM modulation module of the first DC / DC feedback circuit and a second PWM modulation module of the second DC / DC feedback circuit. The first PWM modulation module adjusts the actual voltage output of the first DC / DC feedback circuit, and the second PWM modulation module adjusts the actual voltage output of the second DC / DC feedback circuit.

2. The power supply current balancing control method according to claim 1, wherein: The first virtual impedance Z / 2 is connected to the first DC / DC feedback circuit, and the second virtual impedance Z / 2 is connected to the second DC / DC feedback circuit. The impedance values ​​of the first virtual impedance Z / 2 and the second virtual impedance Z / 2 are both half of the virtual impedance Z.

3. The power supply current balancing control method according to claim 1, wherein: The first PWM modulation module controls the PWM duty cycle of the first DC / DC feedback circuit, and the second PWM modulation module controls the PWM duty cycle of the second DC / DC feedback circuit.

4. A power supply current balancing device, characterized in that: include: a control module, controlling the first DC / DC converter and the second DC / DC converter to operate in a current mode, wherein the first DC / DC converter and the second DC / DC converter are connected in parallel; An acquisition module, configured to acquire a first feedback voltage U1 and a first feedback current I1 of a first DC / DC feedback circuit and a second feedback voltage U2 and a second feedback current I2 of a second DC / DC feedback circuit; a calculation module, calculating a virtual impedance Z according to the first feedback voltage U1, the first feedback current I1, the second feedback voltage U2, and the second feedback current I2, where Z=U1 / I1-U2 / I2; The calling and control module calls the virtual impedance Z, compensates the feedback voltage, performs a PID control operation, obtains a PID control variable, and uses the PID control variable to control a first PWM modulation module of the first DC / DC feedback circuit and a second PWM modulation module of the second DC / DC feedback circuit, wherein the first PWM modulation module adjusts the actual voltage output of the first DC / DC feedback circuit, and the second PWM modulation module adjusts the actual voltage output of the second DC / DC feedback circuit.

5. The power supply current balancing device according to claim 4, wherein: The first virtual impedance Z / 2 is connected to the first DC / DC feedback circuit, and the second virtual impedance Z / 2 is connected to the second DC / DC feedback circuit. The impedance values ​​of the first virtual impedance Z / 2 and the second virtual impedance Z / 2 are both half of the virtual impedance Z.

6. The power supply current balancing device according to claim 5, wherein: One end of the first virtual impedance Z / 2 is connected to the first current transformer, and the other end is connected to the signal input end of the first DC / DC feedback circuit; one end of the second virtual impedance Z / 2 is connected to the second current transformer, and the other end is connected to the signal input end of the second DC / DC feedback circuit.

7. The power supply current balancing device according to claim 6, wherein: It also includes a first adding operation module, which is used to input the first virtual impedance Z / 2 and the first feedback voltage U1, and output the first net feedback voltage U1_Fed and the first reference voltage Uref1 as the input of the compensator after operation.

8. The power supply current balancing device according to claim 7, wherein: The compensator includes a voltage compensator and a current compensator. The first net feedback voltage U1_Fed and the first reference voltage Uref1 are calculated and then pass through the voltage compensator and the current compensator respectively. The output signals are transmitted to the first PWM modulation module.

9. The power supply current balancing device according to claim 6, wherein: It also includes a second addition operation module, which is used to input the second virtual impedance Z / 2 and the second feedback voltage U2, and the output second net feedback voltage U2_Fed and the second reference voltage Uref2 are used as the input of the compensator after operation.

10. The power supply current balancing device according to claim 9, wherein: The compensator includes a voltage compensator and a current compensator. The second net feedback voltage U2_Fed and the second reference voltage Uref2 are calculated and successively pass through the voltage compensator and the current compensator, and the output signals are transmitted to the second PWM modulation module.

11. An electric vehicle, characterized in that: The invention comprises the power supply current balancing device according to any one of claims 4 to 10.

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