Bidirectional active equalization circuit of battery management system

Abstract

The invention discloses a bidirectional active equalization circuit of a battery management system, which comprises a plurality of battery cell clusters, a plurality of battery cells are connected in series to form a battery cell cluster, and a plurality of battery cell clusters are connected in series and in parallel to form a battery cluster; in each battery cell cluster, each battery cell is connected with a battery cell inversion module, the battery cell inversion module inverts direct current of the battery cell into alternating current, and the alternating current inverted by the battery cell inversion module is connected to a battery cell cluster alternating current bus of the battery cell cluster in parallel through the battery cell cluster inversion module; in each battery cell cluster, the alternating current bus of the battery cell cluster is converted into alternating current through the battery cell cluster inversion module, and then the alternating current is connected to the battery cluster alternating current bus of the battery cluster in parallel; the transmission direction and size of electric energy in the battery cell, the battery cell cluster and the battery cluster are adjusted by adjusting the phase difference between the battery cell cluster inversion module and the battery cell inversion module; and the battery cells or the battery cell clusters which need to be actively regulated and balanced are subjected to phase adjustment through the battery cell inversion modules or the battery cell cluster inversion modules which are connected with the battery cells or the battery cell clusters so as to be charged or discharged.

Description

Technical Field

[0001] The present application belongs to the technical field of battery management systems, and specifically refers to a bidirectional active balancing circuit for a battery management system. Background Art

[0002] In the current battery field, a battery pack is composed of many cells connected in series and in parallel. Multiple cells are first connected in series to form a basic cell cluster, and more cell clusters are connected in series and in parallel to form a battery system with higher voltage or larger capacity. Therefore, the difference in charge of the single cell greatly affects the operating efficiency of the battery pack, so adding a balancing circuit to the battery pack is an indispensable measure.

[0003] The active balancing methods currently used in battery management systems mainly include capacitor, inductor, and transformer. Using capacitors or inductors as energy storage elements, or through transformers, part of the energy of high-voltage cells or clusters is transferred to low-voltage cells or clusters to balance the charge status of each cell or cluster, avoid short boards, and thus improve the charging and discharging efficiency of the entire battery pack.

[0004] Although active balancing charging and discharging has high efficiency, the cost of implementation is still relatively high. Whether it is capacitive, inductive, or through a transformer DCDC bidirectional conversion method, the circuit is relatively complex, difficult to control, and has low reliability. Some also encounter problems such as slow balancing speed and low efficiency. Therefore, active balancing in battery management systems is rarely used. Summary of the invention

[0005] In order to overcome the deficiencies of the prior art, the present application provides a battery management system bidirectional active balancing circuit with a simple architecture and easy control.

[0006] The present invention provides a bidirectional active balancing circuit for a battery management system, wherein the bidirectional active balancing circuit comprises a plurality of battery cell clusters, wherein a plurality of battery cells are connected in series to form a battery cell cluster, and a plurality of battery cell clusters are connected in series and in parallel to form a battery cluster;

[0007] In each of the battery cell clusters, each of the battery cells is connected to a battery cell inverter module, the battery cell inverter module inverts the direct current of the battery cell into alternating current, and the alternating current inverted by the battery cell inverter module is connected in parallel to the battery cell cluster AC busbar of the battery cell cluster through the battery cell cluster inverter module;

[0008] In each of the battery cell clusters, the AC busbars of the battery cell clusters are connected in parallel to the battery cluster AC busbars of the battery clusters after being converted into AC power by the battery cell cluster inverter module;

[0009] The phase difference between the cell cluster inverter module and the cell inverter module is adjusted to adjust the direction and size of electric energy transmission in the cell, the cell cluster and the battery cluster; the cell or the cell cluster that needs to be actively regulated and balanced is charged or discharged by adjusting the phase of the cell inverter module or the cell cluster inverter module connected to itself.

[0010] According to the bidirectional active balancing circuit of the battery management system provided in the present application, each of the battery cell clusters also includes a microprocessor unit, the microprocessor unit is connected to each of the battery cell inverter modules, and the microprocessor unit is connected to the battery cell cluster inverter module.

[0011] According to the bidirectional active balancing circuit of the battery management system provided in the present application, the battery cell inverter modules are all half-bridge circuit inverters or full-bridge circuit inverters; the battery cell inverter modules are all controlled by the microprocessor unit for voltage phase control.

[0012] According to the bidirectional active balancing circuit of the battery management system provided in the present application, the output ends of the half-bridge circuit inverter or the output ends of the full-bridge circuit inverter in each of the battery cell inverter modules are connected in parallel to form the battery cell cluster AC bus.

[0013] According to the bidirectional active balancing circuit of the battery management system provided in the present application, the AC voltages of the half-bridge circuit inverter or the full-bridge circuit inverter located on the same AC bus of the battery cell cluster are of the same frequency.

[0014] According to the bidirectional active balancing circuit of the battery management system provided in the present application, the battery cell cluster inverter modules each include two half-bridge circuit inverters or two full-bridge circuit inverters, and the two half-bridge circuit inverters or the two full-bridge circuit inverters are interconnected; the battery cell cluster inverter modules each perform voltage phase control by the microprocessor unit.

[0015] According to the bidirectional active balancing circuit of the battery management system provided in the present application, the two half-bridge circuit inverters or the two full-bridge circuit inverters in the cell cluster inverter module respectively perform voltage inversion on the cell cluster AC bus and the battery cluster AC bus.

[0016] According to the bidirectional active balancing circuit of the battery management system provided in the present application, the input end of the cell cluster inverter module is connected to the cell cluster AC bus; the output end of the cell cluster inverter module constitutes the battery cluster AC bus.

[0017] According to the bidirectional active balancing circuit of the battery management system provided in the present application, the AC voltages of the half-bridge circuit inverter or the full-bridge circuit inverter located on the same AC bus of the battery cluster have the same frequency.

[0018] According to the bidirectional active balancing circuit of the battery management system provided by the present application, when the power of the battery cells in the same battery cell cluster is discharged to the battery cell cluster AC bus in the battery cell cluster, the AC voltage output by the battery cell inverter module is controlled to lead the AC bus output by the battery cell cluster inverter module by a phase angle θ;

[0019] When the cell cluster AC bus in the same cell cluster charges the cells in the cell cluster, the AC voltage output by the cell inverter module is controlled to lag behind the AC bus output by the cell cluster inverter module by a phase angle θ.

[0020] The beneficial effects of the present invention are as follows: the present application provides a bidirectional active balancing circuit for a battery management system, in each cell cluster, each cell inverts direct current into alternating current through a cell inverter module, and then the alternating current inverted by the cell inverter module is connected in parallel to the cell cluster AC busbar of the cell cluster through the cell cluster inverter module. The alternating current between cell clusters is also converted into alternating current through the cell cluster inverter module and then connected in parallel to the battery cluster AC busbar of the battery cluster. By adjusting the phase difference between the cell inverter module and the cell cluster inverter module, the direction and magnitude of energy transfer can be controlled: for single cells or cell clusters that need to be balanced, only their inverter modules need to be turned on and the appropriate phases need to be adjusted to achieve charging or discharging, and to achieve power balance between cells or cell clusters; and for single cells or cell clusters that do not need to be balanced, only the corresponding inverter modules need to be turned off. The present application provides a battery management system with a bidirectional active balancing circuit architecture that is simple and easy to control; each cell cluster unit can be independently balanced off-grid or synchronously balanced on-grid, which can speed up the balancing speed; the bidirectional active balancing circuit has strong scalability and is particularly suitable for applications where multiple cell clusters are connected in series or in parallel or where plugging and unplugging is required. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The technical solution and other beneficial effects of the present application will be made apparent by describing in detail the specific implementation methods of the present application in conjunction with the accompanying drawings.

[0022] Figure 1 This is a schematic diagram of the circuit structure of the bidirectional active balancing of the battery management system provided in this embodiment. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0024] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0025] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the various specific processes and material examples provided by the present application, but those of ordinary skill in the art can appreciate the application of other processes and / or the use of other materials.

[0026] The embodiments of the present application are now further described in conjunction with the accompanying drawings and specific implementation methods.

[0027] Figure 1 This is a schematic diagram of the circuit structure of the bidirectional active balancing of the battery management system provided in this embodiment.

[0028] like Figure 1 As shown, the bidirectional active balancing circuit includes a plurality of battery cell clusters, a plurality of battery cells are connected in series to form a battery cell cluster, and a plurality of battery cell clusters are connected in series and in parallel to form a battery cluster;

[0029] In each of the battery cell clusters, each of the battery cells is connected to a battery cell inverter module, the battery cell inverter module inverts the direct current of the battery cell into alternating current, and the alternating current inverted by the battery cell inverter module is connected in parallel to the battery cell cluster AC busbar of the battery cell cluster through the battery cell cluster inverter module;

[0030] In each of the battery cell clusters, the AC busbars of the battery cell clusters are connected in parallel to the battery cluster AC busbars of the battery clusters after being converted into AC power by the battery cell cluster inverter module;

[0031] The phase difference between the cell cluster inverter module and the cell inverter module is adjusted to adjust the direction and size of electric energy transmission in the cell, the cell cluster and the battery cluster; the cell or the cell cluster that needs to be actively regulated and balanced is charged or discharged by adjusting the phase of the cell inverter module or the cell cluster inverter module connected to itself.

[0032] Each of the battery cell clusters also includes a microprocessor unit, the microprocessor unit is connected to each of the battery cell inverter modules, and the microprocessor unit is connected to the battery cell cluster inverter module. The microprocessor unit drives each of the battery cell inverter modules and the battery cell cluster inverter module. The microprocessor unit also has a serial communication interface input TX, a serial communication interface output RX, and a synchronization signal input and output Sync.

[0033] In this embodiment, the cell inverter modules are all half-bridge circuit inverters or full-bridge circuit inverters; the cell inverter modules are all voltage phase controlled by the microprocessor unit. The output ends of the half-bridge circuit inverter or the full-bridge circuit inverter in each cell inverter module are connected in parallel to form the cell cluster AC bus. The AC voltages of the half-bridge circuit inverter or the full-bridge circuit inverter on the same cell cluster AC bus are of the same frequency.

[0034] The cell cluster inverter modules each include two half-bridge circuit inverters or two full-bridge circuit inverters, and the two half-bridge circuit inverters or the two full-bridge circuit inverters are interconnected; the cell cluster inverter modules each perform voltage phase control by the microprocessor unit. The two half-bridge circuit inverters or the two full-bridge circuit inverters in the cell cluster inverter module respectively perform voltage inversion on the cell cluster AC bus and the battery cluster AC bus. The input end of the cell cluster inverter module is connected to the cell cluster AC bus; the output end of the cell cluster inverter module constitutes the battery cluster AC bus. The AC voltages of the half-bridge circuit inverter or the full-bridge circuit inverter located on the same battery cluster AC bus are of the same frequency.

[0035] Specifically, Figure 1As shown, each battery cell cluster is composed of multiple battery cells (C0, C1, C2...Cn-1, Cn) connected in series, and each battery cell has a battery cell inverter module connected thereto. Each battery cell cluster has a battery cell cluster inverter module. The battery cell inverter module and the battery cell cluster inverter module can both adopt a half-bridge circuit inverter or a full-bridge circuit inverter. In order to reduce the number of components in the circuit, in this embodiment, the battery cell inverter module and the battery cell cluster inverter module are both described using a half-bridge circuit inverter.

[0036] In a cell cluster, the two ends (C0, C1) of the first cell are respectively connected to a cell half-bridge circuit inverter. Specifically, the cell half-bridge circuit inverter includes a cell transformer Tz1, a cell resonant inductor Lsz1, a cell high-level resonant capacitor Csz1-b, a cell low-level resonant capacitor Csz1-a, a cell high-level inverter switch tube QHz1, a cell low-level inverter switch tube QLz1, a cell high-level driver Drz1-b, and a cell low-level driver Drz1-a;

[0037] The battery cell high-level inverter switch tube QHz1 is controlled by the battery cell high-level driver Drz1-b to be turned on or off; the battery cell low-level inverter switch tube QLz1 is controlled by the battery cell low-level driver Drz1-a to be turned on or off; the battery cell high-level driver Drz1-b and the battery cell low-level driver Drz1-a are respectively connected to the H1-Drv drive output terminal and the L1-Drv drive output terminal of the microprocessor unit to receive the drive signal of the microprocessor unit; the primary coil of the battery cell transformer Tz1 is connected to the battery cell resonant inductor Lsz1, the battery cell high-level resonant capacitor Csz1-b, the battery cell low-level resonant capacitor Csz1-a, the battery cell high-level inverter switch tube QHz1 and the battery cell low-level inverter switch tube QLz1.

[0038] That is, the cell high-level resonant capacitor Csz1-b and the cell low-level resonant capacitor Csz1-a are connected in series to the C0 and C1 ends of the first cell; the gate of the cell high-level inverter switch tube QHz1 is connected to the cell high-level driver Drz1-b, and the cell high-level driver Drz1-b is connected to the first cell high-level H1-Drv drive output end of the microprocessor unit; the gate of the cell low-level inverter switch tube QLz1 is connected to the cell low-level driver Drz 1-a, the battery low level driver Drz1-a is connected to the first battery low level L1-Drv driving output end of the microprocessor unit; the battery high level resonant capacitor Csz1-b and the battery low level resonant capacitor Csz1-a form a bridge with the battery high level inverter switch tube QHz1 and the battery low level inverter switch tube QLz1, and the diagonal of the bridge is connected to the primary coil of the battery transformer Tz1, and the primary coil of the battery transformer Tz1 is also connected to the battery resonant inductor Lsz1. The secondary coil of the battery transformer Tz1 outputs AC power.

[0039] The secondary coils of the cell transformer Tz1 of each cell are connected in parallel to form the cell cluster AC bus.

[0040] like Figure 1 As shown, the cell cluster inverter module includes two cell cluster half-bridge circuit inverters, namely, the first cell cluster half-bridge circuit inverter and the second cell cluster half-bridge circuit inverter. The first cell cluster half-bridge circuit inverter includes the first cell cluster high-level inverter switch tube QHc1, the first cell cluster low-level inverter switch tube QLc1, the first cell cluster high-level resonant capacitor Csc1-b and the first cell cluster low-level resonant capacitor Csc1-a. The first cell cluster high-level inverter switch tube QHc1, the first cell cluster low-level inverter switch tube QLc1, the first cell cluster high-level resonant capacitor Csc1-b and the first cell cluster low-level resonant capacitor Csc1-a form a bridge, and the diagonal of the bridge connects the cell cluster AC bus.

[0041] The gate of the first battery cell cluster high-level inverter switch tube QHc1 is connected to the first battery cell cluster high-level driver Drc1-b, and the gate of the first battery cell cluster low-level inverter switch tube QLc1 is connected to the first battery cell cluster low-level driver Drc1-a. The first battery cell cluster high-level driver Drc1-b and the first battery cell cluster low-level driver Drc1-a are respectively connected to the Hc1-Drv drive output terminal and the Lc1-Drv drive output terminal of the microprocessor unit.

[0042] The half-bridge circuit inverter of the second cell cluster includes a second cell cluster high-level inverter switch tube QHc2, a second cell cluster low-level inverter switch tube QLc2, a second cell cluster high-level resonant capacitor Csc2-b and a second cell cluster low-level resonant capacitor Csc2-a. The second cell cluster high-level inverter switch tube QHc2, the second cell cluster low-level inverter switch tube QLc2, the second cell cluster high-level resonant capacitor Csc2-b and the second cell cluster low-level resonant capacitor Csc2-a form a bridge, and the diagonal of the bridge is connected to the primary coil of the cell cluster transformer Tc1. The primary coil of the cell cluster transformer Tc1 is also connected to the cell cluster resonant inductor Lsc1.

[0043] The secondary coils of the cell cluster transformer Tc1 of each cell cluster are connected in parallel to form the battery cluster AC bus. The battery cluster AC bus outputs current as a total output, and the battery cluster AC bus includes a positive terminal Cbus+ and a negative terminal Cbus-.

[0044] The gate of the second battery cell cluster high-level inverter switch tube QHc2 is connected to the second battery cell cluster high-level driver Drc2-b, and the gate of the second battery cell cluster low-level inverter switch tube QLc2 is connected to the second battery cell cluster low-level driver Drc2-a. The second battery cell cluster high-level driver Drc2-b and the second battery cell cluster low-level driver Drc2-a are respectively connected to the Hc2-Drv drive output terminal and Lc2-Drv drive output terminal of the microprocessor unit.

[0045] The working principle of the bidirectional active balancing circuit of the battery management system provided in this embodiment is as follows:

[0046] In this embodiment, in each of the battery cell clusters, the voltage in the AC bus of the battery cell cluster is inverted into AC power through the control of the half-bridge circuit inverter of the first battery cell cluster, and the voltage on the AC bus is isolated and stepped down through the battery cell cluster transformer Tc1 and added to the output end of the half-bridge circuit inverter of each battery cell. The transformation ratio of the battery cell cluster transformer Tc1 is the number of series-connected batteries in the battery cluster.

[0047] When the electric power of the electric cells in the same electric cell cluster is discharged to the electric cell cluster AC bus in the electric cell cluster, the AC voltage output by the electric cell inverter module is controlled to lead the AC bus output by the electric cell cluster inverter module by a phase angle θ;

[0048] When the cell cluster AC bus in the same cell cluster charges the cells in the cell cluster, the AC voltage output by the cell inverter module is controlled to lag behind the AC bus output by the cell cluster inverter module by a phase angle θ.

[0049] Specifically, the half-bridge circuit inverter of each cell also inverts the cell voltage into an AC voltage. Since the voltage difference between the cells is small, generally only a few tenths of a volt, the amplitude of the AC bus voltage after being stepped down by the cell cluster transformer is similar to the output amplitude of the half-bridge circuit inverter of each cell, and is temporarily considered to be equal to VB / 2. If a full-bridge architecture is used, the amplitude is VB. Here, VB is the voltage of the single cell.

[0050] When the power of a single battery cell is high and the energy needs to be transferred to the AC bus, the AC power output by the half-bridge circuit inverter of the battery cell can lead the half-bridge circuit inverter of the first battery cell cluster by a phase angle θ. The phase causes a voltage difference V=VB*SQRT(1-COS(θ)), and this voltage difference is added to the series network of the battery cell's resonant inductor Lszn and the battery cell's resonant capacitor Cszn.

[0051] The resonant frequency of the series network of the resonant inductor Lszn and the resonant capacitor Cszn of the battery cell is lower than the inverter frequency, so the current on the resonant inductor Lszn of the battery cell will lag 90 degrees, and the phase difference between it and the output of the half-bridge circuit inverter of the battery cell is equal to θ / 2. When the phase difference is less than 90 degrees, the output power P=V*I*Cos(θ / 2) of the half-bridge circuit inverter of the battery cell is positive, and the battery cell discharges and transmits energy to the AC bus. Generally, in order to avoid too much reactive current to reduce efficiency, the lead angle θ is generally controlled within 45 degrees.

[0052] On the contrary, when the capacity of a battery cell is low and needs to be charged, the phase of the half-bridge circuit inverter of the battery cell will lag behind the half-bridge circuit inverter of the first battery cell cluster by a phase angle θ. At this time, the output power P of the half-bridge circuit inverter of the battery cell is negative, and the battery cell absorbs energy from the AC bus to charge.

[0053] For a battery cell that does not require power balancing in the circuit, the half-bridge circuit inverter of the battery cell and the half-bridge circuit inverter of the first battery cell cluster in the battery cell cluster are set to be in phase, or the drivers of the half-bridge circuit inverter of the battery cell and the half-bridge circuit inverter of the first battery cell cluster in the battery cell cluster are directly turned off.

[0054] If several half-bridge circuit inverters of battery cells are working at the same time, some are configured to lead and some are configured to lag, energy can be transferred directly between the half-bridge circuit inverters of several battery cells, and the switch tube QHc1 / QLc1 in the half-bridge circuit inverter of the first battery cell cluster in the battery cell cluster can be turned off.

[0055] The circuit and principle of balancing between cell clusters are the same as those of balancing between cells, except that at least two cell clusters are required for balancing. For cell clusters that do not need to be balanced, it is only necessary to turn off the switch tube QHc2 / QLc2 in the half-bridge circuit inverter of the second cell cluster in the cell cluster.

[0056] The present application provides a bidirectional active balancing circuit for a battery management system. In each cell cluster, each cell inverts direct current into alternating current through a cell inverter module, and then connects the alternating current inverted by the cell inverter module to the cell cluster AC busbar of the cell cluster in parallel through the cell cluster inverter module. The alternating current between cell clusters is also converted into alternating current through the cell cluster inverter module and then connected in parallel to the battery cluster AC busbar of the battery cluster. By adjusting the phase difference between the cell inverter module and the cell cluster inverter module, the direction and magnitude of energy transfer can be controlled: for single cells or cell clusters that need to be balanced, only need to turn on their inverter modules and adjust the appropriate phase to achieve charging or discharging, and achieve power balance between cells or cell clusters; and for single cells or cell clusters that do not need to be balanced, only need to turn off the corresponding inverter modules. The present application provides a battery management system with a bidirectional active balancing circuit architecture that is simple and easy to control; each cell cluster unit can be independently balanced off-grid or synchronously balanced on-grid, which can speed up the balancing speed; the bidirectional active balancing circuit has strong scalability and is particularly suitable for applications where multiple cell clusters are connected in series or in parallel or where plugging and unplugging is required.

[0057] Although the preferred embodiments of the embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concepts. Therefore, the attached claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention. Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or terminal device including a series of elements includes not only those elements, but also other elements that are not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0058] The above is a detailed introduction to a bidirectional active balancing circuit of a battery management system provided in an embodiment of the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solution and core idea of ​​the present application. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the present application.

Claims

1. A bidirectional active balancing circuit for a battery management system, characterized in that: The bidirectional active balancing circuit includes a plurality of battery cell clusters, wherein a plurality of battery cells are connected in series to form a battery cell cluster, and a plurality of battery cell clusters are connected in series and in parallel to form a battery cluster; In each of the battery cell clusters, each of the battery cells is connected to a battery cell inverter module, the battery cell inverter module inverts the direct current of the battery cell into alternating current, and the alternating current inverted by the battery cell inverter module is connected in parallel to the battery cell cluster AC busbar of the battery cell cluster through the battery cell cluster inverter module; In each of the battery cell clusters, the AC busbars of the battery cell clusters are connected in parallel to the battery cluster AC busbars of the battery clusters after being converted into AC power by the battery cell cluster inverter module; The phase difference between the cell cluster inverter module and the cell inverter module is adjusted to adjust the direction and size of electric energy transmission in the cell, the cell cluster and the battery cluster; the cell or the cell cluster that needs to be actively regulated and balanced is charged or discharged by adjusting the phase of the cell inverter module or the cell cluster inverter module connected to itself.

2. The bidirectional active balancing circuit of the battery management system according to claim 1, characterized in that: Each of the battery cell clusters also includes a microprocessor unit, which is connected to each of the battery cell inverter modules and the battery cell cluster inverter module.

3. The bidirectional active balancing circuit of the battery management system according to claim 2, characterized in that: The cell inverter modules are all half-bridge circuit inverters or full-bridge circuit inverters; the cell inverter modules are all voltage phase controlled by the microprocessor unit.

4. The bidirectional active balancing circuit of the battery management system according to claim 3, characterized in that: The output ends of the half-bridge circuit inverter or the output ends of the full-bridge circuit inverter in each of the battery cell inverter modules are connected in parallel to form the battery cell cluster AC bus.

5. The bidirectional active balancing circuit of the battery management system according to claim 4, characterized in that: The AC voltages of the half-bridge circuit inverter or the full-bridge circuit inverter located on the same AC busbar of the battery cell cluster are of the same frequency.

6. The bidirectional active balancing circuit of the battery management system according to claim 3, characterized in that: The cell cluster inverter modules each include two half-bridge circuit inverters or two full-bridge circuit inverters, and the two half-bridge circuit inverters or the two full-bridge circuit inverters are interconnected; the cell cluster inverter modules each perform voltage phase control by the microprocessor unit.

7. The bidirectional active balancing circuit of the battery management system according to claim 6, characterized in that: The two half-bridge circuit inverters or the two full-bridge circuit inverters in the cell cluster inverter module respectively perform voltage inversion on the cell cluster AC bus and the battery cluster AC bus.

8. The bidirectional active balancing circuit of the battery management system according to claim 6, characterized in that: The input end of the battery cell cluster inverter module is connected to the battery cell cluster AC bus; the output end of the battery cell cluster inverter module constitutes the battery cluster AC bus.

9. The bidirectional active balancing circuit of the battery management system according to claim 8, characterized in that: The AC voltages of the half-bridge circuit inverter or the full-bridge circuit inverter located on the same AC bus of the battery cluster have the same frequency.

10. The bidirectional active balancing circuit of the battery management system according to claim 8, characterized in that: When the electric power of the electric cells in the same electric cell cluster is discharged to the electric cell cluster AC bus in the electric cell cluster, the AC voltage output by the electric cell inverter module is controlled to lead the AC bus output by the electric cell cluster inverter module by a phase angle θ; When the cell cluster AC bus in the same cell cluster charges the cells in the cell cluster, the AC voltage output by the cell inverter module is controlled to lag behind the AC bus output by the cell cluster inverter module by a phase angle θ.

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