Energy storage battery equalization device and equalization method

Abstract

The application relates to the technical field of lithium batteries, in particular to a storage battery equalization device and an equalization method. The storage battery equalization device comprises a main control chip, a storage battery pack, a plurality of bidirectional converters and a low-voltage bus; a plurality of single batteries of the storage battery pack are arranged in correspondence with the plurality of bidirectional converters; the main control chip can calculate the electric quantity value of each single battery and screen out the single batteries with the highest and lowest electric quantity values; when the difference between the highest and lowest electric quantity values reaches a predetermined electric quantity value, the main control chip controls the bidirectional converter corresponding to the single battery with the highest electric quantity value to step up to the low-voltage bus, and controls the bidirectional converter corresponding to the single battery with the lowest electric quantity value to step down to the single battery. The storage battery equalization device and the equalization method solve the problems that the existing active equalization circuit is complex, the cost is high, the high-voltage side of the unidirectional converter is prone to damage, and the unidirectional converter occupies a large volume.

Description

Technical Field

[0001] This application relates to the field of lithium battery technology, and in particular to an energy storage battery balancing device and balancing method. Background Technology

[0002] With the development of new energy electric vehicles and new power systems, lithium-ion batteries are widely used due to their advantages such as small size and high energy density. However, the voltage of a single lithium-ion battery cell is too low, and in practical applications, dozens or hundreds of cells are often connected in series or parallel, which places higher demands on the performance consistency of individual cells. However, due to manufacturing processes, the voltage of each individual cell will more or less deviate after a period of use. Therefore, the task of regulating this voltage falls on the equalization function module of the BMS (Battery Management System).

[0003] Currently, the balancing function of BMS systems on the market is divided into two types: active balancing and passive balancing. Passive balancing discharges relatively high-voltage individual cells during charging, converting energy into heat, which is then dissipated in the balancing resistor. However, while passive balancing has the advantage of low cost, it also has significant drawbacks: excessive heat generation and insufficient balancing current, which is insufficient for large-capacity individual cells, resulting in poor balancing performance.

[0004] Another method is active balancing. Active balancing uses a gating circuit to couple multiple relatively high-voltage individual cells to the DC bus through a DC / DC unidirectional converter to achieve energy recovery. However, active balancing circuits are complex and costly, and the high-voltage side of the DC / DC unidirectional converter is prone to damage, which can lead to the failure of the entire active balancing function. In addition, the DC / DC unidirectional converter occupies a large volume, affecting the overall layout of the equipment. Summary of the Invention

[0005] The purpose of this application is to provide an energy storage battery balancing device and balancing method, thereby solving the problems of existing active balancing circuits being complex and costly, the high voltage side of DC / DC unidirectional converters being easily damaged, and the large volume occupied by DC / DC unidirectional converters.

[0006] According to a first aspect of this application, an energy storage battery balancing device is provided. The energy storage battery balancing device includes a main control chip, an energy storage battery pack, multiple bidirectional converters, and a low-voltage bus. The energy storage battery pack includes multiple individual battery cells, and the multiple bidirectional converters are correspondingly arranged with the multiple individual battery cells. The main control chip can calculate the charge value of each individual battery cell and filter out the individual battery cell with the highest charge value and the individual battery cell with the lowest charge value. The main control chip pre-stores a predetermined charge value. When the difference between the highest charge value and the lowest charge value reaches the predetermined charge value, the main control chip controls the bidirectional converter corresponding to the individual battery cell with the highest charge value to boost the voltage to the low-voltage bus to discharge the current individual battery cell. The main control chip also controls the bidirectional converter corresponding to the individual battery cell with the lowest charge value to step down the voltage to charge the current individual battery cell. When the difference between the highest charge value and the lowest charge value is lower than the predetermined charge value, the corresponding bidirectional converter is turned off.

[0007] In any of the above technical solutions, the energy storage battery balancing device further includes a data acquisition chip; the data acquisition chip cyclically acquires the current value, voltage value, and temperature value of each individual battery cell, and sends the acquired current value, voltage value, and temperature value to the main control chip, so that the main control chip cyclically calculates the charge value of each individual battery cell; in each cycle, when the difference between the highest charge value and the lowest charge value reaches the predetermined charge value, the main control chip controls the bidirectional converter corresponding to the individual battery cell with the highest charge value to boost the voltage to the low-voltage bus, and controls the bidirectional converter corresponding to the individual battery cell with the lowest charge value to step down the voltage to the individual battery cell; in each cycle, when the difference between the highest charge value and the lowest charge value is lower than the predetermined charge value, the corresponding bidirectional converter is turned off.

[0008] In any of the above technical solutions, the low-voltage bus is further described as a 5V low-voltage bus.

[0009] In any of the above technical solutions, the main control chip is further capable of sending the power value of each individual battery cell to an external terminal.

[0010] In any of the above technical solutions, the energy storage battery balancing device further includes an external charging and discharging interface and an external charger; the external charging and discharging interface is connected to the low-voltage bus; when the external charging and discharging interface is connected to the external charger, the external terminal can send a charging command to the main control chip, and the main control chip controls the bidirectional converter corresponding to the single cell to be charged to step down the voltage, so as to realize the charging of the current single cell.

[0011] In any of the above technical solutions, the energy storage battery balancing device further includes an external discharge device; when the external charging and discharging interface is connected to the external discharge device, the external terminal can send a discharge command to the main control chip, and the main control chip controls the bidirectional converter corresponding to the single cell to be discharged to boost the voltage to the low-voltage bus, so as to realize the discharge of the current single cell.

[0012] In any of the above technical solutions, the external discharge device is further defined as a resistor or an electronic load.

[0013] In any of the above technical solutions, the external terminal is further defined as the vehicle's control system.

[0014] In any of the above technical solutions, the main control chip is a microcontroller, and the acquisition chip is an analog front-end chip.

[0015] According to a second aspect of this application, an equalization method is provided, which is applied to the energy storage battery equalization device described above.

[0016] In any of the above technical solutions, the equalization method further includes:

[0017] The main control chip calculates the power value of each individual battery cell in a loop, and in each loop, selects the individual battery cell with the highest power value and the individual battery cell with the lowest power value.

[0018] The main control chip calculates the difference between the highest and lowest battery levels, wherein the main control chip has a predetermined battery level stored in advance;

[0019] When the difference between the highest and lowest battery levels exceeds the predetermined battery level, the main control chip controls the bidirectional converter corresponding to the single cell with the highest battery level to boost the voltage to the low-voltage bus to discharge the current single cell. The main control chip also controls the bidirectional converter corresponding to the single cell with the lowest battery level to step down the voltage to charge the current single cell.

[0020] When the difference between the highest and lowest power values ​​is lower than the predetermined power value, the corresponding bidirectional converter is turned off.

[0021] The energy storage battery balancing device according to this application includes a main control chip, an energy storage battery pack, multiple bidirectional converters, and a low-voltage bus. The energy storage battery pack includes multiple individual battery cells, and the multiple bidirectional converters are correspondingly configured with the multiple individual battery cells. The main control chip can calculate the charge value of each individual battery cell and filter out the individual battery cells with the highest and lowest charge values. The main control chip pre-stores predetermined charge values. When the difference between the highest and lowest charge values ​​reaches the predetermined charge value, the main control chip controls the bidirectional converter corresponding to the individual battery cell with the highest charge value to boost the voltage to the low-voltage bus to discharge the current individual battery cell. The main control chip also controls the bidirectional converter corresponding to the individual battery cell with the lowest charge value to step down the voltage to charge the current individual battery cell.

[0022] Based on the above technical features, the beneficial effects of this application are as follows:

[0023] During the charging process of the energy storage battery pack, the main control chip will adjust and balance the voltage of multiple individual cells based on the difference between the highest and lowest charge values ​​obtained.

[0024] Specifically, when the difference between the highest and lowest battery levels reaches a predetermined value, the control chip controls the bidirectional converter corresponding to the cell with the highest battery level to boost the voltage to the low-voltage bus, thereby discharging the current cell (the voltage gradually decreases during the discharge process); at the same time, it controls the bidirectional converter corresponding to the cell with the lowest battery level to step down the voltage to the cell, thereby charging the current cell (the voltage gradually increases during the charging process).

[0025] In other words, the low-voltage bus of this application can store the electrical energy released by the high-capacity single cell and use the stored electrical energy to charge the low-capacity single cell, thereby realizing the energy transfer between the two single cells and ultimately making the voltage of the two single cells with high and low capacities tend to be balanced.

[0026] In summary, the balancing method of this application has a simple circuit, low cost, and low voltage on both sides of the bidirectional converter, making it less prone to damage (even if damaged, it will only affect the balancing function of one single cell). Moreover, the volume of multiple bidirectional converters is smaller (compared to the original single unidirectional converter), and the layout is flexible and convenient.

[0027] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 A schematic diagram of an energy storage battery equalization device according to an embodiment of this application is shown.

[0030] Icons: 100 - Main control chip; 200 - Acquisition chip; 300 - Energy storage battery pack; 400 - Bidirectional converter; 500 - Low voltage bus; 600 - External charging and discharging interface; 700 - External terminal. Detailed Implementation

[0031] The following detailed embodiments are provided to help the reader gain a comprehensive understanding of the methods, apparatus, and / or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatus, and / or systems described herein will be apparent after understanding the disclosure of this application. For example, the order of operations described herein is merely illustrative and is not limited to the order set forth herein; changes that will be apparent after understanding the disclosure of this application are possible, except for operations that must occur in a specific order. Furthermore, for clarity and brevity, descriptions of features known in the art may be omitted.

[0032] The features described herein may be implemented in different forms and should not be construed as being limited to the examples described herein. Rather, the examples described herein have been provided merely to illustrate some of the many feasible ways of implementing the methods, apparatus, and / or systems described herein that will be apparent upon understanding the disclosure of this application.

[0033] Throughout the specification, when an element (such as a layer, region, or substrate) is described as being "on" another element, "connected to" another element, "bonded to" another element, "on" another element, or "covering" another element, it may be directly "on" another element, "connected to" another element, "bonded to" another element, "on" another element, or "covering" another element, or there may be one or more other elements in between. In contrast, when an element is described as being "directly on" another element, "directly connected to" another element, "directly bonded to" another element, "directly on" another element, or "directly covering" another element, there may be no other elements in between.

[0034] As used herein, the term “and / or” includes any one of the relevant items listed and any combination of any two or more items.

[0035] Although terms such as “first,” “second,” and “third” may be used herein to describe individual components, assemblies, regions, layers, or parts, these components, assemblies, regions, layers, or parts are not limited by these terms. Rather, these terms are used only to distinguish one component, assembly, region, layer, or part from another. Therefore, without departing from the teachings of the examples described herein, the first component, assembly, region, layer, or part referred to as the second component, assembly, region, layer, or part may also be referred to as the second component, assembly, region, layer, or part.

[0036] For ease of description, spatial relation terms such as “above,” “upper,” “below,” and “lower” are used herein to describe the relationship between one element and another, as shown in the accompanying drawings. Such spatial relation terms are intended to include not only the orientation depicted in the drawings but also different orientations of the device during use or operation. For example, if the device in the drawings is flipped, an element described as being “above” or “upper” relative to another element will subsequently be “below” or “lower” relative to that other element. Therefore, the term “above” includes both “above” and “below” orientations depending on the spatial orientation of the device. The device may also be positioned in other ways (e.g., rotated 90 degrees or in other orientations), and the spatial relation terms used herein will be interpreted accordingly.

[0037] The terminology used herein is for the purpose of describing various examples only and is not intended to limit this disclosure. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms “comprising,” “including,” and “having” enumerate the stated features, quantities, operations, components, elements, and / or combinations thereof, but do not exclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof.

[0038] Variations in the shapes shown in the accompanying drawings may occur due to manufacturing techniques and / or tolerances. Therefore, the examples described herein are not limited to the specific shapes shown in the accompanying drawings, but include changes in shape that may occur during manufacturing.

[0039] The features of the examples described herein can be combined in various ways that will be apparent upon understanding the disclosure of this application. Furthermore, although the examples described herein have a wide variety of constructions, other constructions are possible, as will be apparent upon understanding the disclosure of this application.

[0040] The first aspect of this application provides an energy storage battery balancing device, thereby solving the problems of existing active balancing circuits being complex and costly, the DC / DC unidirectional converter being prone to damage on the high-voltage side, and the DC / DC unidirectional converter occupying a large volume.

[0041] The following reference Figure 1 This application provides a detailed description of an energy storage battery equalization device according to some embodiments.

[0042] like Figure 1 As shown, the energy storage battery equalization device of this application includes a main control chip 100 (preferably a microcontroller), an energy storage battery pack 300 (including multiple individual cells connected in series), multiple bidirectional converters 400 (a DC boost or buck converter capable of controlling the direction of current through external commands), and a low-voltage bus 500 (capable of converging all voltages or currents to a bus below a safe voltage, preferably a 5V low-voltage bus 500).

[0043] The energy storage battery pack 300 includes multiple individual battery cells connected in series, and multiple bidirectional converters 400 are configured corresponding to multiple individual battery cells. That is, each bidirectional converter 400 is connected in parallel with its corresponding individual battery cell, and each bidirectional converter 400 is connected to the low-voltage bus 500.

[0044] The main control chip 100 can calculate the power value of each individual battery cell and filter out the individual battery cells with the highest power value and the lowest power value. The main control chip 100 has a predetermined power value stored in advance. When the difference between the highest power value and the lowest power value reaches the predetermined power value, the main control chip 100 controls the bidirectional inverter 400 corresponding to the individual battery cell with the highest power value to boost the voltage to the low-voltage bus 500 to discharge the current individual battery cell. The main control chip 100 controls the bidirectional inverter 400 corresponding to the individual battery cell with the lowest power value to step down the voltage to charge the current individual battery cell.

[0045] Based on the above technical features, the beneficial effects of this application are as follows:

[0046] During the charging process of the energy storage battery pack 300, since the voltage of each individual cell is inconsistent, the main control chip 100 will adjust and balance the voltage of multiple individual cells based on the difference between the highest and lowest charge values ​​obtained.

[0047] Specifically, when the difference between the highest and lowest battery levels reaches a predetermined value, the control chip controls the bidirectional converter 400 corresponding to the cell with the highest battery level to boost the voltage to the low-voltage bus 500, thereby discharging the current cell (the voltage gradually decreases during the discharge process); at the same time, it controls the bidirectional converter 400 corresponding to the cell with the lowest battery level to step down the voltage to charge the current cell (the voltage gradually increases during the charging process).

[0048] In other words, the low-voltage bus 500 of this application can store the electrical energy released by the high-capacity single cell and use the stored electrical energy to charge the low-capacity single cell, thereby realizing the energy transfer between the two single cells and ultimately making the voltage of the two single cells with high and low capacities tend to be balanced.

[0049] In summary, the balancing method of this application has a simple circuit, low cost, and low voltage on both sides of the bidirectional converter 400, making it less prone to damage (even if damaged, it will only affect the balancing function of one single cell). Moreover, the volume of multiple bidirectional converters 400 is smaller (compared to the original single unidirectional converter), and the layout is flexible and convenient.

[0050] Further, see also Figure 1 In the embodiments of this application, the energy storage battery equalization device further includes a data acquisition chip 200 (preferably an analog front-end chip).

[0051] The data acquisition chip 200 cyclically collects the current, voltage, and temperature values ​​of each individual battery cell and sends these values ​​to the main control chip 100 via SPI or IIC communication. The main control chip 100 then cyclically calculates the charge value of each individual battery cell. It should be noted that the main control chip 100 can calculate the charge value based on the current, voltage, and temperature values; the specific calculation method is existing technology and will not be elaborated upon here.

[0052] Within each cycle, when the difference between the highest and lowest battery levels reaches a predetermined value, the main control chip 100 controls the bidirectional converter 400 corresponding to the cell with the highest battery level to boost the voltage to the low-voltage bus 500, and controls the bidirectional converter 400 corresponding to the cell with the lowest battery level to step down the voltage to the cell. When the voltages of the two cells with high and low battery levels tend to balance, that is, when the difference between the highest and lowest battery levels falls below the predetermined value within this cycle, the two corresponding bidirectional converters 400 are turned off.

[0053] After completing the balancing adjustment in this cycle, the balancing adjustment of the other two individual cells with high and low charge levels continues in the next cycle.

[0054] Furthermore, it is worth mentioning that the energy storage battery balancing device of this application also includes an online maintenance function, that is, without disassembling individual cells for repair, the faulty individual cell part can be identified through a specific interface, and the faulty part can be repaired through relevant measures.

[0055] Specifically, such as Figure 1 As shown, the energy storage battery equalization device also includes an external interface, an external charging / discharging interface 600, and an external charger. The external charging / discharging interface 600 is connected to the low-voltage bus 500.

[0056] The main control chip 100 can send the power value of each individual battery cell to the external terminal 700 through an external interface, so that staff can check the status of each individual battery cell. For example, the external interface can be a common serial communication method such as CAN, RS485, RS232, TCP / IP, or an interface that matches the vehicle's OBD (On-Board Diagnostics).

[0057] For example, during routine maintenance, the OBD interface of the car can be connected to the main control chip 100 to obtain the power value (voltage) of each individual battery cell. If it is desired to charge some of the individual battery cells with lower voltage, the external charging and discharging interface 600 can be connected to an external charger, and a charging command can be sent to the main control chip 100 through the car's OBD interface (the external terminal 700 implemented) (the charging command is the charging command for a specific individual battery cell). The main control chip 100 controls the bidirectional converter 400 corresponding to the individual battery cell to be charged to step down the voltage, so as to charge the current individual battery cell. When the voltage reaches the equilibrium voltage after charging, the bidirectional converter 400 is automatically turned off.

[0058] In this example, the external charging / discharging interface 600 is used to connect an external charger interface. The external charger interface can be a universal connector such as a USB interface, a TYPE-C interface, or a DC socket, and can be charged using a general mobile phone charger.

[0059] Meanwhile, if you want to discharge some of the higher voltage individual cells, you can connect the external charging / discharging interface 600 to an external discharge device and send a discharge command to the main control chip 100 (the charging command is the discharge command of the specific individual cell) through the car's OBD interface (the external terminal 700). The main control chip 100 controls the bidirectional converter 400 corresponding to the individual cell to be discharged to boost the voltage to the low-voltage bus 500 to discharge the current individual cell. When the voltage reaches the balance voltage after discharge, the bidirectional converter 400 is automatically turned off.

[0060] In this example, the external discharge device can be a high-power resistor or an electronic load.

[0061] Therefore, when staff perform routine maintenance, if the voltage difference is large and the BMS balancing function cannot meet the requirements, any single cell in the energy storage battery pack 300 can be manually charged or discharged to achieve maintenance without disassembly, while avoiding bottleneck effects in the energy storage battery pack 300 and extending its service life.

[0062] In summary, when the energy storage battery pack 300 is charging, the low-voltage bus 500 can store the electrical energy released by the high-capacity individual cells and use the stored electrical energy to charge the low-capacity individual cells, thereby realizing the energy transfer between the two individual cells and ultimately making the voltage of the two individual cells with high and low capacities tend to be balanced.

[0063] Compared with existing technologies, the equalization method of this application has a simpler circuit and lower cost.

[0064] In addition, each individual cell is designed with a small-power bidirectional converter 400. The voltage on both sides of the bidirectional converter 400 is small and it is not easy to be damaged. Even if it is damaged, it will only affect the balancing function of one individual cell.

[0065] Furthermore, each individual cell is designed with a small-power bidirectional converter 400, using a 5V low-voltage bus 500. The low-ratio isolation transformer enables the bidirectional converter 400 to be smaller, lower in cost, and more efficient in conversion. In addition, all electronic components operate below 5V, making the circuit more reliable.

[0066] Moreover, the volume of multiple bidirectional converters 400 is smaller (compared to the original single unidirectional converter), and the layout is flexible and convenient.

[0067] The second aspect of this application provides a balancing method applied to the energy storage battery balancing device described above;

[0068] The equilibrium method includes:

[0069] S1, the acquisition chip 200 cyclically acquires the current value, voltage value and temperature value of each individual cell, and sends the acquired current value, voltage value and temperature value to the main control chip 100.

[0070] S2, the main control chip 100 cyclically calculates the power value of each individual cell.

[0071] S3, in each cycle, selects the individual cells with the highest and lowest charge values.

[0072] S4, the main control chip 100 calculates the difference between the highest and lowest battery levels. When the difference exceeds the predetermined battery level, the main control chip 100 controls the bidirectional converter 400 corresponding to the single cell with the highest battery level to boost the voltage to the low-voltage bus 500 to discharge the current single cell. The main control chip 100 also controls the bidirectional converter 400 corresponding to the single cell with the lowest battery level to step down the voltage to charge the current single cell.

[0073] S5, when the difference between the highest and lowest power values ​​is lower than the predetermined power value, the corresponding two bidirectional converters 400 are shut down.

[0074] S6. After completing the balancing adjustment in this cycle, in the next cycle, continue to balance the other two individual cells with high and low charge levels.

[0075] In addition, in step S2, the main control chip 100 can also send the power value of each individual cell to the external terminal 700 through an external interface so that staff can check the status of each individual cell.

[0076] Afterwards, staff can manually recharge or discharge any individual cell in the energy storage battery pack 300 to achieve maintenance without disassembly.

[0077] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The protection scope of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the scope of the technology disclosed in this application, or make equivalent substitutions for some of the technical features. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the protection scope of this application.

Claims

1. An energy storage battery equalization device, characterized in that, The energy storage battery equalization device includes a main control chip, an energy storage battery pack, multiple bidirectional converters, and a low-voltage bus. The energy storage battery pack includes multiple individual battery cells, and multiple bidirectional converters are configured corresponding to the multiple individual battery cells; The main control chip can calculate the power value of each individual battery cell and filter out the individual battery cells with the highest power value and the individual battery cells with the lowest power value. The main control chip pre-stores a predetermined power value. When the difference between the highest power value and the lowest power value reaches the predetermined power value, the main control chip controls the bidirectional converter corresponding to the single cell with the highest power value to boost the voltage to the low-voltage bus to discharge the current single cell. The main control chip also controls the bidirectional converter corresponding to the single cell with the lowest power value to step down the voltage to charge the current single cell. When the difference between the highest and lowest power values ​​is lower than the predetermined power value, the corresponding bidirectional converter is turned off. The energy storage battery equalization device also includes a data acquisition chip; The acquisition chip cyclically acquires the current value, voltage value, and temperature value of each individual battery cell, and sends the acquired current value, voltage value, and temperature value to the main control chip, so that the main control chip can cyclically calculate the charge value of each individual battery cell; In each cycle, when the difference between the highest and lowest battery values ​​reaches the predetermined battery value, the main control chip controls the bidirectional converter corresponding to the single cell with the highest battery value to boost the voltage to the low-voltage bus, and controls the bidirectional converter corresponding to the single cell with the lowest battery value to step down the voltage to the single cell. In each cycle, when the difference between the highest and lowest power values ​​is lower than the predetermined power value, the corresponding bidirectional converter is turned off. The main control chip can send the power value of each individual battery cell to an external terminal; The energy storage battery equalization device also includes an external charging and discharging interface and an external charger; The external charging / discharging interface is connected to the low-voltage bus; When the external charging / discharging interface is connected to the external charger, the external terminal can send a charging command to the main control chip. The main control chip controls the bidirectional inverter corresponding to the single cell to be charged to step down the voltage, so as to realize the charging of the current single cell.

2. The energy storage battery equalization device according to claim 1, characterized in that, The low-voltage bus is a 5V low-voltage bus.

3. The energy storage battery equalization device according to claim 1, characterized in that, The energy storage battery equalization device also includes an external discharge device; When the external charging / discharging interface is connected to the external discharging device, the external terminal can send a discharge command to the main control chip. The main control chip controls the bidirectional converter corresponding to the single cell to be discharged to boost the voltage to the low-voltage bus, so as to realize the discharge of the current single cell.

4. The energy storage battery equalization device according to claim 3, characterized in that, The external discharge device is a resistor or an electronic load.

5. The energy storage battery equalization device according to claim 1, characterized in that, The external terminal is the vehicle's control system.

6. The energy storage battery equalization device according to claim 1, characterized in that, The main control chip is a microcontroller, and the acquisition chip is an analog front-end chip.

7. An equilibrium method, characterized in that, Applied to the energy storage battery equalization device as described in any one of claims 1-6; The equilibrium method includes: The main control chip calculates the power value of each individual battery cell in a loop, and in each loop, selects the individual battery cell with the highest power value and the individual battery cell with the lowest power value. The main control chip calculates the difference between the highest and lowest battery levels, wherein the main control chip has a predetermined battery level stored in advance; When the difference between the highest and lowest battery levels reaches the predetermined battery level, the main control chip controls the bidirectional converter corresponding to the single cell with the highest battery level to boost the voltage to the low-voltage bus to discharge the current single cell. The main control chip also controls the bidirectional converter corresponding to the single cell with the lowest battery level to step down the voltage to charge the current single cell. When the difference between the highest and lowest power values ​​is lower than the predetermined power value, the corresponding bidirectional converter is turned off.

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