A distributed battery equalization system with auxiliary power supply and two-step equalization control method

Abstract

A distributed battery equalization system with auxiliary power supply and a two-step equalization control method.The battery equalization system is composed of a plurality of battery equalization devices connected to each other, and each battery equalization device is connected to a battery monomer. The system can select a corresponding number of battery equalization devices according to the number of batteries to be equalized, so as to realize simultaneous equalization operation of all batteries to be equalized. The system is a distributed centerless system with flexible and expandable characteristics. The two-step battery equalization control method based on the above battery equalization system requires only local information in calculation compared with the traditional equalization strategy, and therefore has a significant advantage in communication and calculation complexity.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of battery equalization maintenance, in particular to a distributed battery equalization system with auxiliary power supply and a two-step equalization control method. BACKGROUND

[0002] At present, the development scale of new energy vehicles and energy storage technology is increasing day by day. Lithium batteries are widely used due to their excellent energy density characteristics. In engineering practice, multiple battery monomers of the same model are often connected in series and parallel to form a battery pack to meet the use requirements. Due to the differences in working conditions and parameters during the operation of the battery, inconsistencies exist between the battery monomers, which can cause overcharging, overdischarging and life attenuation of the battery monomers. Therefore, the consistency equalization maintenance of lithium batteries has become a hot research topic.

[0003] Consistency equalization can be divided into energy consumption type equalization and non-energy consumption type equalization. Energy consumption type equalization usually has a resistor and a switch connected in parallel at both ends of the battery monomer, and the battery pack state is made consistent by discharging through the resistor. The advantage of energy consumption type equalization is that the principle is simple and easy to implement. The disadvantages of energy consumption type equalization are energy waste, low equalization efficiency, and the generation of heat during the equalization process, which leads to insufficient equalization capacity for large battery packs. Therefore, energy consumption type equalization is often used for the equalization of small battery packs. Non-energy consumption type equalization uses capacitors and inductors as energy transfer carriers to transfer electrical energy between battery monomers and ultimately make the battery monomers reach equilibrium. Non-energy consumption type equalization has no energy consumption in the ideal state, but there is still a small amount of loss in actual application. Non-energy consumption type equalization requires higher cost and more complex control strategy.

[0004] The design of the current battery equalization device limits the number of battery monomers that can be equalized at the same time. The battery equalization device can only simultaneously equalize a limited number of battery units. When the number of battery monomers that need to be equalized is large, a single equalization device cannot complete the task in one operation. If multiple devices are used for simultaneous equalization or a single device is used for multiple operations, the result may be that the batteries in each batch operation reach different equalization states. This not only leads to a doubling of the time required for re-equalization of the batteries, but also increases the complexity of the operation. For example, taking 10 batteries as an example, if they are equalized in two batches, the first 5 batteries after the first equalization may reach an average of 5.5V, while the other 5 batteries after the second equalization may reach an average of 6V. This obviously fails to achieve the goal of making the 10 batteries as a whole reach equilibrium. This inconsistency not only affects the performance of the battery pack, but also shortens the service life of the battery, increases the maintenance cost, and reduces the overall system efficiency.

[0005] Moreover, the traditional consistency algorithm combined with the non-central topology has the problem of communication noise, that is, there is an error in the exchange of state information between distributed nodes, which will lead to a non-smooth convergence process and slow convergence speed of the algorithm, which is not conducive to the accurate control of the charging and discharging current of the battery monomer.

[0006] For example, Chinese invention patent CN114400387A discloses a battery equalization management method and system based on multi-agent game, which includes the following steps: first, according to the attenuation data and current power data of each monomer battery in the battery pack, the state of charge (SOC) data of each monomer battery is determined; second, based on the difference between the SOC data of each monomer battery and the SOC data of other monomer batteries, the Nash equilibrium method is applied to calculate the charging and discharging strategy of each monomer battery in the battery pack; finally, the battery equalization management is carried out according to the obtained charging and discharging strategy.

[0007] In addition, the portability of the battery equalization equipment becomes a problem when the energy storage system deployed in some remote areas is maintained. Specifically, when the environment cannot meet the power supply required by the equalization equipment (for example, the equalization equipment cannot be connected to the power supply, resulting in that the battery cannot be charged and discharged), it will bring great inconvenience to the equalization operation.

[0008] Therefore, developing a solution that can simultaneously and efficiently equalize a large number of battery units is crucial for maintaining the performance and extending the service life of a battery pack composed of numerous battery monomers. In addition, since the present application is based on the idea of non-central distributed topology and consistency algorithm, the traditional consistency algorithm combined with the non-central topology has the problem of communication noise, that is, there is an error in the exchange of state information between distributed nodes, which will lead to a non-smooth convergence process and slow convergence speed of the algorithm, which is not conducive to the accurate control of the charging and discharging current of the battery monomer. SUMMARY

[0009] In view of the defects in the prior art, the purpose of the present application is to provide a distributed battery equalization system with an auxiliary power supply. The system is composed of a plurality of battery equalization devices, each of which is connected to a battery monomer, and its scale can be expanded by adding modules, thereby realizing the simultaneous equalization of different number of battery monomers and solving the problem of large-scale battery monomer equalization.

[0010] To achieve the above purpose, the technical solution adopted by the present application is as follows:

[0011] A distributed battery equalization system, characterized in that the distributed battery equalization system is composed of a plurality of battery equalization devices, each of which is composed of a module M1 and a module M2; each battery equalization device is used to equalize a battery monomer;

[0012] The module M1 includes a battery state detection unit and a communication unit;

[0013] The detection unit is configured to measure the voltage state information of the battery monomer according to the set equalization target;

[0014] The communication unit is configured to communicate with adjacent battery equalization devices, specifically, sending the battery monomer information detected by the detection unit to the adjacent battery equalization devices, and receiving the battery monomer state information sent by the adjacent battery equalization devices;

[0015] The module M2 includes a calculation unit, a charge-discharge control unit and an auxiliary power supply unit;

[0016] The calculation unit is configured to calculate the equalization strategy of each battery monomer according to the detected and received battery monomer information, the equalization strategy being the charge / discharge current value of the corresponding battery monomer in the next period;

[0017] The charge-discharge control unit is configured to control the charge / discharge current of the battery monomer according to the charge / discharge current value of the battery monomer in the next period provided by the calculation unit, to ensure the effectiveness and safety of the equalization process

[0018] The auxiliary power supply unit is configured to provide charging service for the battery monomers equalized by the battery equalization device, or absorb the excess power in the above battery monomers.

[0019] Another object of the present application is to provide a battery two-step equalization control method.

[0020] To achieve the above object, the technical solution adopted by the present application is:

[0021] A battery two-step equalization control method applied to the distributed battery equalization system, characterized in that it comprises the following steps:

[0022] Step 1: each battery equalization device detects the voltage state information of the battery monomer to be equalized connected thereto, and sends the voltage state information to each adjacent battery equalization device through the communication unit;

[0023] Step 2: each battery equalization device receives the state information of the adjacent other battery equalization devices; and calculates the equalization strategy of each battery monomer to be equalized according to a two-stage random planning algorithm based on a consensus algorithm;

[0024] Step 3: controlling the charge / discharge current of the battery monomer to be equalized according to the equalization strategy;

[0025] Step 4: repeating steps 1 to 3 until the voltages of all battery monomers to be equalized connected by the battery equalization devices reach the same level;

[0026] Step 5, after the battery cell balancing is completed, the auxiliary power supply in the battery balancing device is self-balanced.

[0027] On the basis of the above scheme, the two-stage stochastic programming algorithm in step 2 is specifically as follows:

[0028] When the communication between the connected battery balancing devices is due to noise, the error will occur, and the mutual reference value considering the error is shown in the following formula (1):

[0029] ;

[0030] In the above formula (1), is the actual voltage value of the battery cell connected to the i-th battery balancing device at time t; n is the reference value sent by the module i to the module j at time t, and the module j regards it as the actual voltage value of the battery cell connected to the i-th battery balancing device at time t; j is the deviation between the reference voltage value and the actual voltage value at time t in the actual process; n j i i j n n

[0031] The two-stage calculation formula for planning the balancing strategy of each battery cell to be balanced is shown in the following formulas (2) and (3):

[0032] ;

[0033] ;

[0034] When i = 1, n ; ;

[0035] In the above two formulas, is the adjacent value of the target voltage, which will be optimized again in the second stage described in formula (3); is the voltage detected by the i-th battery balancing device at time t; i is the global time-varying proportion coefficient at time t; n represents the set of other battery balancing devices that establish communication connection with the i-th battery balancing device; n i j i ​​​​​​​​​​​​​​​​​The battery equalization device in n The target voltage obtained according to the strategy at the first moment; The target voltage of the first i The target voltage of the battery equalization device in n The target voltage of the first The iteration coefficient is time-varying; The target voltage of the first i The target voltage of the first The voltage of the first i The voltage of the first

[0036] The target voltage of the first i The control strategy of the first n The control strategy of the first The calculation formula of the control strategy of the first

[0037]

[0038] On the basis of the above scheme, the control formula of the charge / discharge current of the battery to be balanced in step 3 is shown as formula (5):

[0039]

[0040] In the above formula (5), The equalization current of the first i The equalization current of the first n The equalization current of the first The equalization current of the first

[0041] On the basis of the above scheme, the specific operation of step 5 is:

[0042] The auxiliary power supply in each battery equalization device is taken out, and is connected in series with a protection resistor to form an auxiliary power supply self-balancing unit, and each auxiliary power supply self-balancing unit is connected in parallel to form a self-balancing circuit; the self-balancing circuit restores the auxiliary power supply to the original power;

[0043] When the auxiliary power supply is insufficient, the external power supply is connected in parallel with the self-balancing circuit to charge the auxiliary power supply with insufficient power for next time.

[0044] The distributed battery equalization system with auxiliary power supply and two-step equalization control method have the following beneficial effects:

[0045] ​​(1) The battery equalization system comprises a plurality of battery equalization devices, each of which is connected to one battery monomer, and the modules are connected to each other to form a multi-agent system, wherein each battery equalization device and the connected battery monomer correspond to a node, and the communication connection between the modules corresponds to an edge in the multi-agent system.

[0046] The system is a centerless distributed system, and each node is independent, so when part of the nodes fail, the entire system can still continue to operate, and will not collapse like a sequential system due to the failure of a node. The system has the characteristics of flexibility and scalability, specifically, the system size can be expanded by adding modules, thereby realizing the simultaneous equalization of different numbers of battery monomers, and solving the problem of large-scale battery monomer equalization.

[0047] The distributed battery equalization system provided by the application has a portable auxiliary power supply, and can complete the battery equalization operation in an environment without an external power supply.

[0048] (2) The battery two-step equalization control method is based on the improved idea of the consistency algorithm, and in the first stage of the algorithm, a large step is used to quickly obtain an approximate value of the consistency strategy. The battery equalization strategy based on the consistency algorithm is a high-efficiency way of managing the energy difference between each battery, which ensures that the released electric quantity in the discharging process and the received electric quantity in the charging process are balanced, so that the energy conservation is achieved at the whole battery pack level, and the battery equalization system does not consume external energy as a whole. The algorithm is suitable for a variety of distributed system models and can provide good consistency in different application scenarios.

[0049] In the second stage, the fluctuation value in the iteration process is smoothed through the averaging step, so that the variance of the obtained result is small, and the result is that the control process is smoother, which is beneficial to the accurate control of the charging and discharging current of the battery monomer. BRIEF DESCRIPTION OF DRAWINGS

[0050] The application has the following drawings:

[0051] Figure 1 The battery equalization device structure diagram of the application;

[0052] Figure 2 The battery equalization system structure diagram of the application;

[0053] Figure 3 The battery two-step equalization control method flow chart of the application;

[0054] Figure 4 The battery equalization system operation schematic diagram of the application;

[0055] Figure 5 The auxiliary power supply working schematic diagram of the application;

[0056] Figure 6 The auxiliary power supply self-balancing parallel circuit schematic diagram of the application;

[0057] Figure 7 The auxiliary power supply self-balancing parallel circuit schematic diagram of the application when the power is insufficient;

[0058] Figure 8 The calculation schematic diagram of the application;

[0059] Figure 9 The calculation network schematic diagram of the application;

[0060] Figure 10 Voltage balancing result diagram under large noise without application of the application;

[0061] Figure 11 Voltage balancing result diagram under large noise with application of the application; DETAILED DESCRIPTION

[0062] The application will be described in detail below with specific embodiments. The following embodiments will help those skilled in the art to further understand the application, but do not limit the application in any form. It should be noted that for those skilled in the art, without departing from the concept of the application, a number of changes and improvements can be made. These are within the scope of protection of the application

[0063] Example 1 Distributed battery balancing system

[0064] I. Battery balancing device

[0065] Figure 1 The application provides a function schematic diagram of a battery balancing device in a distributed battery balancing system with an auxiliary power supply. The device is composed of module M1 (including battery state detection and communication unit) and module M2 (including calculation unit, charge and discharge control unit and auxiliary power supply unit). Each device is connected to a battery monomer to be balanced and exchanges information with the outside world.

[0066] The application provides a distributed portable battery balancing system with an auxiliary power supply. The system is composed of a plurality of battery balancing devices. The number of battery balancing devices is equal to the number of batteries to be balanced. Each battery balancing device includes the following component modules:

[0067] Module M1: including battery state detection and communication unit, responsible for detecting the state information of the battery monomer and communicating with the adjacent battery balancing device. The detected and received information is used as the input of the subsequent consistency control strategy algorithm calculation. The specific functions of each unit include:

[0068] Detection unit: measure the state information (SOC, voltage, capacity) of the battery cell according to the set balancing target;

[0069] Communication unit: communicate with adjacent battery balancing devices, send the battery cell state information detected by the detection unit, and receive the state information sent by the adjacent battery balancing device.

[0070] Module M2: including the calculation unit, the charge and discharge control unit and the auxiliary power supply unit, responsible for calculating the balancing strategy of the battery cell connected by the consistency control strategy according to the state data of the battery cell and the state data sent by the adjacent battery balancing device, and controlling the balancing charge or discharge current of the battery according to the balancing strategy. The specific functions of each unit include:

[0071] Calculation unit: calculate the balancing strategy of the battery cell according to the information detected and received according to the battery balancing maintenance method based on the consistency control strategy proposed in the application, that is, the charge / discharge current of the battery cell in the next period.

[0072] Control unit: control the charge and discharge current of the battery cell according to the charge and discharge strategy determined by the calculation unit.

[0073] Auxiliary power supply unit: the auxiliary power supply unit contains an energy storage power supply, which has a certain energy reserve. Its main function is to provide charging service for the battery cell connected by the balancing device, or to absorb the excess power in the battery cell when needed. In the process, the control unit is responsible for adjusting the size of the charge and discharge current to ensure the effectiveness and safety of the balancing process.

[0074] II. Distributed battery balancing system

[0075] Figure 2 The battery balancing system is composed of multiple battery balancing devices. The battery cells to be balanced are single battery C1, single battery C2, single battery C3…single battery Cn. There is a communication connection between different battery balancing devices. Each device can collect the state information of the battery cell connected to it, and obtain the state information of the battery cell collected by other battery balancing devices with which it establishes communication. According to the control method based on the two-stage stochastic programming algorithm proposed in the application, each battery balancing device controls the charge and discharge of the battery cell according to the obtained information, and finally all the battery cells in the whole system can reach the same state level. It should be noted that the battery balancing maintenance system proposed in the application can be described as a multi-agent system, and the structure of the corresponding multi-agent system is a centerless distributed system. In this system, each battery balancing device is equivalent to an agent node, and the communication between devices is regarded as the communication of the multi-agent system, which is represented by the edges between nodes.

[0076] Example 2 Battery two-step equalization control method

[0077] Figure 3 is a flow chart of a battery equalization maintenance method based on a two-stage stochastic programming algorithm, as Figure 4 The system operation schematic diagram when four devices are included in the system is shown, and the entire method includes the following steps:

[0078] Step one: each node detects its state information, specifically, the battery equalization device samples the voltage state information of each battery monomer at each sampling time, and sends the voltage information to other connected battery equalization devices according to the determined communication relationship;

[0079] Step two: each node receives the state information of other adjacent nodes, specifically, each battery equalization device receives the information of other battery equalization devices, and calculates the equalization strategy of each battery monomer according to the two-stage stochastic programming algorithm based on the consensus algorithm; it should be noted that "adjacent nodes" refer to adjacent nodes in topology, and the adjacent nodes actually represent that the two battery equalization devices exist communication, and the communication rule is determined by the field operator.

[0080] The specific steps of the two-stage stochastic programming algorithm in step two are as follows:

[0081] The voltage of the battery monomer is used to reflect the difference of the battery SOC in the present application, and the communication between the associated battery equalization devices will produce errors due to noise, and the specific formula is:

[0082] wherein, is the actual voltage value of the battery monomer connected to the i-th battery equalization device at time t; n is the reference value sent by the module at time t to the module at time t+1, and the module at time t+1 will regard it as the actual voltage value of the battery monomer connected to the i-th battery equalization device at time t+1; however, in the actual process, due to various reasons such as unstable communication, j there is a deviation between the reference value at time t and the actual value at time t+1 . n j i i j n The calculation formula for each equalization device to plan the equalization strategy of the battery monomer according to the collected voltage and the received voltage information of other modules through the two-stage stochastic programming algorithm is: n

[0083]

[0084] ;​​​​​​​​

[0085] ;

[0086] In particular, when n When =1, .

[0087] in The value is a neighboring value to the target voltage, and will be optimized again in the second stage described in equation (3); For the first i The battery equalization device detected its own first... n Voltage at any given moment; for n The time-varying scaling factor for the entire world at any given moment; Indicates the relationship with the first i Other battery equalization devices that establish communication connections with each other. j A set; It is a time constant; For the first i Battery equalization device n The target voltage obtained according to the strategy at time +1; For the first i Battery equalization device n The target voltage at that moment; For time-varying iteration coefficients; For the first i The target voltage of the battery equalization device at time 1; For the first i Each battery equalizer detects its own voltage at time 1.

[0088] Based on the detected voltage of the individual battery cells connected to the battery equalization device at the current moment and the target voltage, it can be concluded that... n The timing control strategy is formulated as follows:

[0089] ;

[0090] in For the first i Battery equalization device n Timing control strategy. It should be noted that, according to the method proposed in this invention, the calculation process in step two is performed independently by each agent in the system.

[0091] Step 3: Control the charging and discharging current of each battery cell according to the balancing strategy. The formula for calculating the charging and discharging current of a battery cell is:

[0092] ;

[0093] in For the firsti The battery equalization device is in the first n equalization current at the moment; is a certain proportion coefficient.

[0094] It should be noted that the battery equalization device of the present application has an auxiliary power module, and when the method of the present application controls the charging and discharging of the battery monomer to be equalized, the auxiliary power module charges the battery monomer to be equalized or receives the discharged power of the battery monomer to be equalized, as shown in Figure 5 .

[0095] It should be noted that according to the method proposed in the present application, the control process of step three is independently carried out by each agent in the system.

[0096] Step four: repeat steps one to three until the voltages of all battery monomers of the battery equalization device reach the same level.

[0097] Step five: after the equalization of the battery monomers to be equalized is completed, the auxiliary power in the battery equalization device is self-equalized.

[0098] The specific operation is to disassemble the auxiliary power in the battery equalization device and assemble it with a protection resistor to form a self-equalization circuit, so that the auxiliary power is restored to the original power, and if necessary, an external power source is used to charge the auxiliary power for the next equalization.

[0099] The above self-equalization is specifically:

[0100] After the equalization work is completed, the auxiliary power modules of different battery equalization devices will also appear unbalanced, and the auxiliary power modules need to be self-equalized. The present application adopts a simple auxiliary power self-equalization method, which utilizes the characteristics of parallel circuits, and the topology of the self-equalization circuit of the auxiliary power is as shown in Figure 6 The energy storage power of the auxiliary power is connected in parallel through a protection resistor.

[0101] According to the characteristics of the consistency control strategy algorithm, the total output current of all battery monomers in the equalization process satisfies:

[0102] ;

[0103] In the formula, NFor the total number of battery equalization device, according to the above formula, in the ideal case, the application of battery equalization method will not produce actual power consumption, so the self-balancing circuit formed by the auxiliary power supply can make the auxiliary power supply of all battery equalization devices return to the initial state. However, due to the loss of switching devices in the equalization process, a small amount of power consumption will be generated in the actual case. When the power consumption accumulates to a certain extent, the self-balancing circuit formed by the auxiliary power supply needs to be charged. The schematic diagram of charging the auxiliary power supply is shown in Figure 7 It should be noted that the power of the auxiliary power supply module is generally charged to 50% SOC.

[0104] Example 3 calculation example

[0105] In order to facilitate understanding, a battery equalization system calculation example of 6 battery monomers to be equalized is given.

[0106] Figure 8 The battery equalization system calculation example including 6 battery monomers is shown in the schematic diagram.

[0107] Figure 9 The network system schematic diagram of this calculation example is shown in the schematic diagram.

[0108] Figure 10 The voltage equalization result diagram under the condition of large noise without applying the application is shown in the schematic diagram. The convergence speed of the equalization process is slow, the fluctuation is large, it is difficult to control, and the equalization result is not accurate.

[0109] Figure 11 The voltage equalization result diagram under the condition of large noise applying the application is shown in the schematic diagram. After adopting the two-stage stochastic programming algorithm, the convergence speed of the equalization process is accelerated, the fluctuation is small, and the equalization result is more accurate.

[0110] The contents not described in detail in the specification belong to the prior art known to those skilled in the art.

Claims

1. A two-step battery equalization control method, characterized in that, Includes the following steps: Step 1: Each battery equalization device detects the voltage status information of the battery cell to be equalized connected to it, and sends the voltage status information to each adjacent battery equalization device through the communication unit. Step 2: Each battery equalization device receives the status information of other adjacent battery equalization devices; and calculates the equalization strategy for each battery cell to be equalized according to a two-stage stochastic programming algorithm based on consensus algorithm. Step 3: Control the charging / discharging current of the individual battery cells to be balanced according to the balancing strategy; Step 4: Repeat steps 1 to 3 until the voltage of all the battery cells connected to the battery equalization device reaches the same level. Step 5: After the individual battery cells have been balanced, the auxiliary power supply in the battery balancing device is self-balanced. The auxiliary power supply is used to: provide charging services for the battery cells balanced by the battery balancing device, or absorb excess power from the battery cells. The two-stage stochastic programming algorithm described in step 2 is as follows: When communicating between connected battery equalization devices, noise will cause errors. The mutual reference values ​​considering the errors are shown in the following formula (1): ； In the above formula (1), for n At time 1, the first j The actual voltage value of each battery cell connected to the battery equalization device; for n Time Module j Send to module i Reference value, module i Will Considered the first j Each battery equalization device connects to a single battery cell. n The actual voltage value at time t; For in the actual process n The deviation between the reference voltage value and the actual voltage value at a given time; The calculation formulas for the balancing strategy of each battery cell to be balanced are shown in equations (2) and (3) below: ； ； when n When =1, ; In the above two equations, The values ​​near the target voltage will be optimized again in the second stage; For the first i The battery equalizer detected itself in the [number]th [year]. n Voltage at any given moment; for n The time-varying scaling factor of the entire system at any given moment; Indicates the relationship with the first i Other battery equalization devices that establish communication connections with each other. j A set; It is a time constant; For the first i A battery equalization device n The target voltage obtained according to the strategy at time +1; For the first i A battery equalization device n The target voltage at that moment; For time-varying iteration coefficients; For the first i The target voltage of the battery equalization device at time 1; For the first i Each battery equalization device detects its own voltage at time 1; No. i A battery equalization device n Time control strategy The calculation formula is shown in equation (4) below: 。 2. The battery two-step equalization control method as described in claim 1, characterized in that, The formula for calculating the charging / discharging current of the battery cell to be balanced in step 3 is shown in equation (5) below: ； In the above formula (5), For the first i The battery equalization device in the first n Equal current at any given moment; A defined proportionality coefficient.

3. The battery two-step equalization control method as described in claim 1, characterized in that, The specific steps in step 5 are as follows: The auxiliary power supply in each battery balancing device is removed and connected in series with a protection resistor to form an auxiliary power supply self-balancing unit. Each auxiliary power supply self-balancing unit is connected in parallel to form a self-balancing circuit. The self-balancing circuit restores the auxiliary power supply to its original power level. When the auxiliary power supply is low, the external power supply is connected in parallel with the self-balancing circuit to charge the low-power auxiliary power supply for the next balancing use.

4. A distributed battery balancing system applying the two-step battery balancing control method of claim 1, characterized in that, The distributed battery balancing system consists of multiple battery balancing devices, each of which consists of module M1 and module M2; each battery balancing device is used to balance one battery cell. The module M1 includes a battery status detection unit and a communication unit; The detection unit is used to measure the voltage state information of individual battery cells according to the set equalization target; The communication unit is used to communicate with adjacent battery equalization devices, specifically to send the battery cell information detected by the detection unit to the adjacent battery equalization device and to receive the battery cell status information sent by the adjacent battery equalization device. The module M2 includes a computing unit, a charging and discharging control unit, and an auxiliary power supply unit; The calculation unit is used to: calculate the balancing strategy for each battery cell based on the detected and received battery cell information, wherein the balancing strategy is the charging / discharging current value of the corresponding battery cell in the next time period; The charge / discharge control unit is used to: control the charge / discharge current of the battery cells according to the charge / discharge current value of the battery cells in the next period provided by the calculation unit, so as to ensure the effectiveness and safety of the equalization process; The auxiliary power unit is used to: provide charging services for the battery cells balanced by the battery balancing device, or absorb excess power from the aforementioned battery cells.

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