Battery equalization device

Abstract

The application relates to a battery equalization device. The battery equalization device is connected with at least two storage batteries, and the battery equalization device comprises an equalization bus, at least one detection module, a first end of the detection module being connected with each storage battery respectively, and a second end of the detection module being connected with the equalization bus; the detection module is used for detecting current battery performances of each storage battery, and transferring battery energy of each storage battery according to the battery performances of each storage battery through the equalization bus. The battery equalization device can improve battery equalization efficiency.

Description

Technical Field

[0001] This application relates to the field of battery balancing technology, and in particular to a battery balancing device. Background Technology

[0002] During the use of battery packs, battery balancing is a key maintenance and control measure. Its core purpose is to solve the inconsistency problem between individual cells in the battery pack, thereby ensuring the performance, lifespan and safety of the battery pack.

[0003] Current battery balancing methods can be divided into active balancing and passive balancing. However, existing balancing methods suffer from relatively low balancing efficiency. Utility Model Content

[0004] Therefore, it is necessary to provide a battery balancing device that can improve battery balancing efficiency in response to the above-mentioned technical problems.

[0005] In a first aspect, this application provides a battery balancing device. The battery balancing device is connected to at least two batteries, and the battery balancing device includes:

[0006] Equalization bus;

[0007] At least one detection module, wherein the first end of the detection module is connected to each of the batteries respectively, and the second end of the detection module is connected to the equalization bus;

[0008] The detection module is used to detect the current battery performance of each battery and transfer battery energy of each battery according to the battery performance through the equalization bus.

[0009] In one embodiment, the detection module includes:

[0010] At least one main control board, which is connected to each of the batteries respectively, for obtaining the battery performance of each battery;

[0011] At least two switches, each of which corresponds to one of the at least two batteries, each switch is connected to its corresponding battery, and each switch is also connected to the main control board.

[0012] At least two DC-DC bidirectional converters are provided, and each of the at least two DC-DC bidirectional converters corresponds to one of the at least two switches. Each DC-DC bidirectional converter is connected to its corresponding switch, and each DC-DC bidirectional converter is also connected to the equalization bus.

[0013] The main control board is used to control the closing or opening of each switch according to the performance of each battery, so as to transfer the battery energy of each battery.

[0014] In one embodiment, each of the batteries includes a positive terminal and a negative terminal, and the main control board is connected to the negative terminal of each of the batteries respectively;

[0015] Each of the switches includes a first switch terminal and a second switch terminal. The first switch terminal of each of the switches is connected to the positive terminal of the corresponding battery, and the second switch terminal of each of the switches is connected to the negative terminal of the corresponding battery.

[0016] Each DC-DC bidirectional converter includes a first port and a second port. The first port includes a first conversion terminal and a second conversion terminal. The second port includes a third conversion terminal and a fourth conversion terminal. The first conversion terminal of each DC-DC bidirectional converter is connected to the first switch terminal of the corresponding switch. The second conversion terminal of each DC-DC bidirectional converter is connected to the second switch terminal of the corresponding switch. The third conversion terminal and the fourth conversion terminal of each DC-DC bidirectional converter are respectively connected to the equalization bus.

[0017] In one embodiment, the main control board is specifically used to control the closing of the switch corresponding to the battery with the best performance and the switch corresponding to the battery with the worst performance when the battery performances of the batteries are not equal, so as to transfer the battery performance of the battery with the best performance to the battery with the worst performance.

[0018] In one embodiment, the at least two batteries include a plurality of batteries, the at least two switches include a plurality of switches, and the at least two DC-DC bidirectional converters include a plurality of DC-DC bidirectional converters;

[0019] Each of the aforementioned batteries corresponds one-to-one with each of the aforementioned switches and each of the aforementioned DC-DC bidirectional converters.

[0020] In one embodiment, the at least two batteries include a first battery and a second battery, the at least two switches include a first switch and a second switch, and the at least two bidirectional converters include a first bidirectional converter and a second bidirectional converter.

[0021] The main control board is specifically used to control the first switch corresponding to the first battery and the second switch corresponding to the second battery to close when the battery performance of the first battery is better than that of the second battery, and to control the first bidirectional converter corresponding to the first battery to operate in a first working mode and the second bidirectional converter corresponding to the second battery to operate in a second working mode, so as to transfer the battery performance of the first battery to the second battery.

[0022] In one embodiment, the main control board is specifically used to control the closing of the first switch and the second switch when the battery performance of the second battery is better than that of the first battery, and to control the first bidirectional converter corresponding to the first battery to operate in the second working mode, and the second bidirectional converter corresponding to the second battery to operate in the first working mode, so as to transfer the battery performance of the second battery to the first battery.

[0023] In one embodiment, the at least two batteries include a first battery and a second battery, and the at least one main control board includes a first main control board and a second main control board;

[0024] The first main control board is connected to the negative terminal of the first battery and is used to obtain the battery performance of the first battery.

[0025] The second main control board is connected to the negative terminal of the second battery to obtain the battery performance of the second battery.

[0026] In one embodiment, the battery balancing device further includes a controller, which is connected to the first main control board and the second main control board respectively;

[0027] The controller is configured to obtain the battery performance of the first battery from the first main control board and the battery performance of the second battery from the second main control board, and generate a control signal based on the battery performance of the first battery and the battery performance of the second battery, and send the control signal to the first main control board and the second main control board.

[0028] In one embodiment, the controller is specifically configured to generate a first control signal and send the first control signal to the first main control board when the battery performance of the first battery is better than that of the second battery, and to generate a second control signal and send the second control signal to the second main control board when the battery performance of the second battery is better than that of the first battery.

[0029] Wherein, the first control signal represents the transfer of battery performance from the first battery to the second battery, and the second control signal represents the transfer of battery performance from the second battery to the first battery.

[0030] The aforementioned battery balancing device includes a balancing bus, at least two batteries, and at least one detection module. The batteries are connected sequentially. The first end of the detection module is connected to each battery, and the second end is connected to the balancing bus. The detection module can detect the current battery performance of each battery and transfer battery energy according to their performance via the balancing bus. For example, it can transfer the battery energy from the best-performing battery to the worst-performing battery. During this energy transfer process, excess battery energy does not need to be released, and the battery energy of the poor-performing battery can be replenished. This allows for high-efficiency, high-power energy transfer while balancing the battery energy, thereby improving the battery balancing efficiency. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of a battery balancing device in one embodiment;

[0032] Figure 2 This is a schematic diagram of a battery balancing device in another embodiment;

[0033] Figure 3 This is a schematic diagram of a battery balancing device in another embodiment;

[0034] Explanation of reference numerals in the attached figures:

[0035] Equalization bus: 10; Detection module: 20; Controller: 30; Main control board: 201;

[0036] Switch: 202; DC-DC bidirectional converter: 203; First switch: 2021;

[0037] Second switch: 2022; First bidirectional converter: 2031; Second bidirectional converter: 2032;

[0038] First main control board: 2011; Second main control board: 2012. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0041] It should be noted that the terms "first" and "second" in the embodiments of this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of those features. It is understood that the terms "first," "second," etc., used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0042] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0043] When used herein, the singular forms of “a,” “an,” and “ / the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0044] Battery packs are typically composed of multiple individual cells connected in series or parallel. Even if the parameters (capacity, voltage, internal resistance, self-discharge rate, etc.) of the individual cells are as consistent as possible at the factory, the differences between the individual cells will gradually increase over long-term use. If battery balancing is not performed, it may lead to problems such as reduced battery pack capacity, shortened lifespan, and degraded performance. Therefore, battery balancing is necessary to adjust the charge and discharge states of the individual cells and reduce or eliminate parameter differences between them.

[0045] Battery balancing methods typically include passive balancing and active balancing. Passive balancing: This method uses resistors to dissipate excess charge from overvoltage cells as heat. It is simple and low-cost, but it is a lossy balancing process, wasting energy and having low efficiency. It is suitable for small-capacity battery packs. Active balancing: This method uses energy transfer circuits (such as inductors, capacitors, and DC-DC converters) to transfer energy from overvoltage cells to undervoltage cells. It is highly efficient (energy recovery) and suitable for large-capacity battery packs (such as electric vehicles and energy storage systems). However, inductive balancing uses a series connection, and the energy path is greatly affected by the state of the battery pack, resulting in a long energy transfer path and low efficiency. Although capacitor balancing uses a parallel connection, the energy transferred per cell is small, resulting in low efficiency.

[0046] In view of this, this application proposes a battery balancing device to improve battery balancing efficiency.

[0047] In one embodiment, such as Figure 1 As shown, a battery balancing device is provided, comprising: a balancing bus 10, at least two batteries, and at least one detection module 20; the batteries are connected sequentially, and the first end of the detection module 20 is connected to each battery respectively, while the second end of the detection module 20 is connected to the balancing bus 10. The detection module 20 is used to detect the current battery performance of each battery and transfer battery energy of each battery according to the battery performance through the balancing bus 10.

[0048] The balancing bus 10 is a power bus used to connect various batteries, providing a unified channel for balanced energy transfer between different batteries. Cells with excessively high voltage or charge can discharge through the balancing bus 10, releasing energy into the bus, while cells with excessively low voltage or charge can obtain energy from the bus for charging, thereby achieving energy balance between cells, reducing the layout of power cables, improving the efficiency of charge balancing, and extending battery cycle life.

[0049] A storage battery is an energy storage device that converts chemical energy into electrical energy and can be repeatedly charged and discharged. Optionally, a storage battery can be a battery pack or a single battery cell. It is understood that during use, batteries should be protected from excessive charging and discharging, and ambient temperature should be controlled, requiring regular maintenance. Optionally, the battery performance can include voltage, temperature, internal resistance, etc. In this embodiment, the positive and negative terminals of multiple storage batteries can be connected sequentially.

[0050] The detection module 20 is a functional unit used to detect the battery performance of the batteries at the current moment and to transfer the battery energy of each battery. It can be understood that, in order to ensure the overall balance of the battery system, the energy of batteries with better performance can be transferred to batteries with poorer performance.

[0051] In this embodiment, the detection module 20 can acquire the current battery performance of each battery in real time, and then determine the battery with the best performance and the battery with the worst performance based on the performance of each battery. Then, the battery energy of the battery with the best performance is released to the equalization bus 10, and then the battery with the worst performance can obtain battery energy from the equalization bus 10, thereby transferring the battery energy of each battery.

[0052] The aforementioned battery balancing device includes a balancing bus, at least two batteries, and at least one detection module. The batteries are connected sequentially. The first end of the detection module is connected to each battery, and the second end is connected to the balancing bus. The detection module can detect the current battery performance of each battery and transfer battery energy based on their performance via the balancing bus. For example, it can transfer the battery energy from the best-performing battery to the worst-performing battery. During this energy transfer process, excess battery energy does not need to be released, and the battery energy of the poor-performing battery can be replenished. This allows for high-efficiency, high-power energy transfer while balancing the battery energy, thereby improving the battery balancing efficiency.

[0053] In one embodiment, such as Figure 2 As shown, the detection module 20 includes: at least one main control board 201, at least two switches 202, and at least two DC-DC bidirectional converters 203. The main control board 201 is connected to each battery to obtain the battery performance of each battery. Each of the at least two switches 202 corresponds to one of the at least two batteries, and each switch 202 is also connected to the main control board 201. Each of the at least two DC-DC bidirectional converters 203 corresponds to one of the at least two switches 202, and each DC-DC bidirectional converter is also connected to the equalization bus 10. The main control board 201 controls the closing or opening of each switch 202 according to the performance of each battery to transfer battery energy.

[0054] The main control board 201 is the control unit in the detection module 20 used to acquire battery performance and implement the battery energy transfer process based on battery performance. Optionally, the main control board 201 can be a microprocessor (microcontroller unit, MCU) or a digital signal processor (DSP). Optionally, the number of main control boards 201 can be one, two, or three; this embodiment does not limit this. Taking one main control board 201 as an example, the main control board 201 in the detection module 20 will be described below.

[0055] The switch 202 is a device used to connect or disconnect the transmission path between the battery and the detection module 20 and the equalization bus 10. For example, if the switch 202 is closed, the transmission path between the battery and the detection module 20 and the equalization bus 10 can be connected; if the switch 202 is open, the transmission path between the battery and the detection module 20 and the equalization bus 10 cannot be connected. Optionally, the switch 202 can be a mechanical switch or an electronic switch. The mechanical switch can include a single-pole switch or a double-pole switch, and this embodiment does not limit this.

[0056] It should be noted that there is a one-to-one correspondence between at least two batteries and at least two switches 202, meaning one battery is connected to one switch. Each battery may include a positive terminal and a negative terminal. For one possible implementation, please refer to [the documentation / reference]. Figure 2 Taking the above-mentioned switch 202 as a double-pole double-throw mechanical switch as an example, each switch 202 may include a first switch element and a second switch terminal. In this way, the first switch terminal of each switch 202 is connected to the positive terminal of the corresponding battery, and the second switch terminal of each switch 202 is connected to the negative terminal of the corresponding battery.

[0057] Among them, the DC-DC bidirectional converter 203 is a power conversion device that enables bidirectional energy flow between two DC power sources. It can convert voltage from the input terminal (e.g., power source A) to the output terminal (e.g., power source B), and vice versa. In this embodiment, the DC-DC bidirectional converter 203 can be used to convert the battery energy of one battery to another.

[0058] It should be noted that at least two DC-DC bidirectional converters 203 correspond one-to-one with at least two switches 202, meaning one switch 202 is connected to one DC-DC bidirectional converter 203. For details, please refer to [link / reference]. Figure 2 Each DC-DC bidirectional converter 203 may include a first port and a second port. The first port may include a first conversion terminal and a second conversion terminal, and the second port may include a third conversion terminal and a fourth conversion terminal. Thus, the first conversion terminal of each DC-DC bidirectional converter can be connected to the first switching terminal of the corresponding switch 202, and the second conversion terminal of each DC-DC bidirectional converter can be connected to the second switching terminal of the corresponding switch 202. The third and fourth conversion terminals of each DC-DC bidirectional converter are respectively connected to the equalization bus 10.

[0059] In this embodiment, the main control board 201 can obtain the current battery performance from each battery and compare the performance of each battery. Then, when the battery performance of each battery is not equal, it controls the switch 202 corresponding to the battery with the best performance and the switch 202 corresponding to the battery with the worst performance to close. This enables the transmission path between the battery with the best performance and the detection module 20 and the equalization bus 10, as well as the transmission path between the battery with the worst performance and the detection module 20 and the equalization bus 10. Then, it can control the battery energy of the battery with the best performance to be released onto the equalization bus 10, and control the battery with the worst performance to obtain battery energy from the equalization bus 10.

[0060] In this embodiment, the detection module includes at least one main control board, at least two switches, and at least two DC-DC bidirectional converters. The main control board is connected to each battery to obtain the battery performance of each battery. The at least two switches correspond one-to-one with the at least two batteries, and each switch is connected to its corresponding battery and also to the main control board. The at least two DC-DC bidirectional converters correspond one-to-one with the at least two switches, and each DC-DC bidirectional converter is connected to its corresponding switch and also to the equalization bus. In this way, the main control board can obtain the battery performance from each battery and control the switches to close or open according to the battery performance to transfer the battery energy of each battery. Due to the integrated design of the detection module, the line connection between the transmission paths in the battery equalization process is simplified, thereby improving the speed of battery energy transfer and thus improving the battery equalization efficiency.

[0061] In one embodiment, at least two batteries include multiple batteries, at least two switches 202 include multiple switches 202, and at least two DC-DC bidirectional converters 203 include multiple DC-DC bidirectional converters 203; each battery corresponds one-to-one with each switch 202 and each DC-DC bidirectional converter 203.

[0062] It is understood that the battery balancing device provided in this application embodiment can simultaneously perform energy balancing on multiple batteries. When multiple batteries are included, the battery balancing device may include multiple switches 202 and multiple DC-DC bidirectional converters 203, and the number of switches 202 and multiple DC-DC bidirectional converters 203 is the same as the number of batteries.

[0063] As one possible implementation method, please continue to refer to Figure 2 At least two batteries, including a first battery and a second battery, at least two switches 202, including a first switch 2021 and a second switch 2022, and at least two DC-DC bidirectional converters 203, including a first bidirectional converter 2031 and a second bidirectional converter 2032.

[0064] The main control board 201 is specifically used to control the first switch 2021 corresponding to the first battery and the second switch 2022 corresponding to the second battery to close when the battery performance of the first battery is better than that of the second battery, and to control the first bidirectional converter 2031 corresponding to the first battery to work in a first working mode and the second bidirectional converter 2032 corresponding to the second battery to work in a second working mode, so as to transfer the battery performance of the first battery to the second battery.

[0065] The main control board 201 is also specifically used to control the first switch 2021 and the second switch 2022 to close when the battery performance of the second battery is better than that of the first battery, and to control the first bidirectional converter 2031 corresponding to the first battery to work in the second working mode and the second bidirectional converter 2032 corresponding to the second battery to work in the first working mode, so as to transfer the battery performance of the second battery to the first battery.

[0066] In this embodiment, since there can be multiple batteries, the detection module can be equipped with multiple switches and multiple bidirectional converters, so that each battery corresponds to each switch and each DC-DC bidirectional converter, thereby enabling simultaneous battery energy balancing of multiple batteries and improving balancing efficiency.

[0067] In one embodiment, such as Figure 3 As shown, at least two batteries include a first battery and a second battery, and at least one main control board 201 includes a first main control board 2011 and a second main control board 2012; the first main control board 2011 is connected to the negative terminal of the first battery and is used to obtain the battery performance of the first battery; the second main control board 2012 is connected to the negative terminal of the second battery and is used to obtain the battery performance of the second battery.

[0068] Please continue to refer to Figure 3 The battery balancing device also includes a controller 30, which is connected to the first main control board 2011 and the second main control board 2012. The controller 30 can obtain the battery performance of the first battery from the first main control board 2011 and the battery performance of the second battery from the second main control board 2012. Then, based on the battery performance of the first battery and the second battery, it generates a control signal and sends the control signal to the first main control board 2011 and the second main control board 2012.

[0069] In this embodiment, the controller 30 can generate a first control signal when the battery performance of the first battery is better than that of the second battery. The first control signal can represent the transfer of battery performance from the first battery to the second battery. The controller 30 sends the first control signal to the first main control board 2011, so that the first main control board 2011 can close the switch 202 corresponding to the first battery according to the first control signal to release the battery energy of the first battery to the equalization bus 10. When the battery performance of the second battery is better than that of the first battery, the controller 30 generates a second control signal and sends the second control signal to the second main control board 2012, so that the second main control board 2012 can close the switch 202 corresponding to the second battery according to the second control signal to control the second battery to obtain battery energy from the equalization bus 10.

[0070] As one possible implementation, if the detection module 20 includes multiple main control boards 201, each main control board 201 can be connected to the controller 30 simultaneously. In this way, the controller 30 can simultaneously obtain multiple battery performance data from multiple main control boards 201, determine the optimal performance and the worst performance data from the multiple battery performance data, and then generate corresponding control signals. The control signals are then sent to the main control board 201 corresponding to the optimal performance and the main control board 201 corresponding to the worst performance, respectively, to control the two main control boards 201 to close the corresponding switches 202, and to control the battery energy of the battery corresponding to the optimal performance to be released to the equalization bus 10, and to control the battery corresponding to the worst performance to obtain battery energy from the equalization bus 10.

[0071] In this embodiment, when there are at least two batteries, including a first battery and a second battery, the detection module may include a first main control board and a second main control board. The first main control board is connected to the negative terminal of the first battery and can obtain the battery performance of the first battery. The second main control board is connected to the negative terminal of the second battery and can obtain the battery performance of the second battery. This allows the controller included in the battery balancing device to generate corresponding control signals based on the battery performance of the first battery and the second battery, thereby controlling the first and second main control boards to connect the transmission paths between the first and second batteries and the balancing bus, thus achieving battery balancing between the first and second batteries.

[0072] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0073] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A battery balancing device, characterized in that, The battery balancing device is connected to at least two batteries, and the battery balancing device includes: Equalization bus; At least one detection module, wherein the first end of the detection module is connected to each of the batteries respectively, and the second end of the detection module is connected to the equalization bus; The detection module is used to detect the current battery performance of each battery and transfer battery energy of each battery according to the battery performance through the equalization bus.

2. The battery balancing device according to claim 1, characterized in that, The detection module includes: At least one main control board, which is connected to each of the batteries respectively, for obtaining the battery performance of each battery; At least two switches, each of which corresponds to one of the at least two batteries, each switch is connected to its corresponding battery, and each switch is also connected to the main control board. At least two DC-DC bidirectional converters are provided, and each of the at least two DC-DC bidirectional converters corresponds to one of the at least two switches. Each DC-DC bidirectional converter is connected to its corresponding switch, and each DC-DC bidirectional converter is also connected to the equalization bus. The main control board is used to control the closing or opening of each switch according to the performance of each battery, so as to transfer the battery energy of each battery.

3. The battery balancing device according to claim 2, characterized in that, Each of the aforementioned batteries includes a positive terminal and a negative terminal, and the main control board is connected to the negative terminal of each of the aforementioned batteries respectively; Each of the switches includes a first switch terminal and a second switch terminal. The first switch terminal of each of the switches is connected to the positive terminal of the corresponding battery, and the second switch terminal of each of the switches is connected to the negative terminal of the corresponding battery. Each DC-DC bidirectional converter includes a first port and a second port. The first port includes a first conversion terminal and a second conversion terminal. The second port includes a third conversion terminal and a fourth conversion terminal. The first conversion terminal of each DC-DC bidirectional converter is connected to the first switch terminal of the corresponding switch. The second conversion terminal of each DC-DC bidirectional converter is connected to the second switch terminal of the corresponding switch. The third conversion terminal and the fourth conversion terminal of each DC-DC bidirectional converter are respectively connected to the equalization bus.

4. The battery balancing device according to claim 2, characterized in that, The main control board is specifically used to control the closing of the switch corresponding to the battery with the best performance and the switch corresponding to the battery with the worst performance when the battery performance of each battery is not equal, so as to transfer the battery performance of the battery with the best performance to the battery with the worst performance.

5. The battery balancing device according to claim 2, characterized in that, The at least two batteries include multiple batteries, the at least two switches include multiple switches, and the at least two DC-DC bidirectional converters include multiple DC-DC bidirectional converters; Each of the aforementioned batteries corresponds one-to-one with each of the aforementioned switches and each of the aforementioned bidirectional converters.

6. The battery balancing device according to claim 2, characterized in that, The at least two batteries include a first battery and a second battery, the at least two switches include a first switch and a second switch, and the at least two DC-DC bidirectional converters include a first bidirectional converter and a second bidirectional converter. The main control board is specifically used to control the first switch corresponding to the first battery and the second switch corresponding to the second battery to close when the battery performance of the first battery is better than that of the second battery, and to control the first bidirectional converter corresponding to the first battery to operate in a first working mode and the second bidirectional converter corresponding to the second battery to operate in a second working mode, so as to transfer the battery performance of the first battery to the second battery.

7. The battery balancing device according to claim 6, characterized in that, The main control board is specifically used to control the closing of the first switch and the second switch when the battery performance of the second battery is better than that of the first battery, and to control the first bidirectional converter corresponding to the first battery to operate in the second working mode, and the second bidirectional converter corresponding to the second battery to operate in the first working mode, so as to transfer the battery performance of the second battery to the first battery.

8. The battery balancing device according to claim 2, characterized in that, The at least two batteries include a first battery and a second battery, and the at least one main control board includes a first main control board and a second main control board; The first main control board is connected to the negative terminal of the first battery and is used to obtain the battery performance of the first battery. The second main control board is connected to the negative terminal of the second battery to obtain the battery performance of the second battery.

9. The battery balancing device according to claim 8, characterized in that, The battery balancing device further includes a controller, which is connected to the first main control board and the second main control board respectively; The controller is configured to obtain the battery performance of the first battery from the first main control board and the battery performance of the second battery from the second main control board, and generate a control signal based on the battery performance of the first battery and the battery performance of the second battery, and send the control signal to the first main control board and the second main control board.

10. The battery balancing device according to claim 9, characterized in that, The controller is specifically configured to generate a first control signal and send the first control signal to the first main control board when the battery performance of the first battery is better than that of the second battery, and to generate a second control signal and send the second control signal to the second main control board when the battery performance of the second battery is better than that of the first battery. Wherein, the first control signal represents the transfer of battery performance from the first battery to the second battery, and the second control signal represents the transfer of battery performance from the second battery to the first battery.

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