Battery system active SOC equalization method and battery system

Abstract

The invention provides an active SOC equalization method for a battery system and the battery system. The method comprises the following steps: judging whether a target battery system has an SOC equalization demand or not according to a maximum SOC value, a minimum SOC value and an SOC mean value in the target battery system; if it is judged that the target battery system has the SOC equalization requirement, determining the equalization level to which each battery cell belongs according to the maximum SOC value or the minimum SOC value and the SOC value of each battery cell in the target battery system; and charging or discharging the battery cells in each equalization level according to a level priority sequence, so that the SOC values of the battery cells in the target battery system are equalized. According to the invention, equalization demand judgment and battery cell grade division are carried out based on the SOC values of the battery cells, and the battery cells are equalized according to the grade priority. The whole calculation process is simple, the SOC value balancing strategy is simplified, and implementation is easy. And meanwhile, the battery cells are balanced according to the level priority, so that the balancing efficiency can be improved.

Description

Technical Field

[0001] The present application relates to the field of energy storage, and more specifically, to a battery system active SOC balancing method and a battery system. Background Art

[0002] Battery systems are widely used in new energy vehicles and energy storage. A battery system is usually composed of multiple cells. The difference in cell SOC consistency largely determines the performance of the battery system. In addition, the SOC consistency level of all cells in the battery system is also closely related to the safety of the entire battery system. The cell SOC balancing technology in the battery system plays a vital role in battery system management. However, the existing SOC balancing strategy is very complex and difficult to implement. Summary of the invention

[0003] In view of this, an object of the embodiments of the present application is to provide a battery system active SOC balancing method and a battery system, which can simplify the battery system SOC value balancing strategy.

[0004] In a first aspect, an embodiment of the present application provides a method for active SOC balancing of a battery system, comprising: judging whether there is a SOC balancing requirement for the target battery system according to a maximum SOC value, a minimum SOC value and a mean SOC value in the target battery system; if it is determined that there is a SOC balancing requirement for the target battery system, determining the balancing level to which each battery cell belongs according to the maximum SOC value or the minimum SOC value and the SOC value of each battery cell in the target battery system; and charging or discharging the battery cells in each balancing level respectively in order of level priority so as to balance the SOC values ​​of each battery cell in the target battery system.

[0005] In the above implementation process, the target battery system balancing demand is directly determined based on the SOC value of the battery cell in the target battery system, and the battery cell level is divided, and then the battery cells in the balancing level are charged or discharged according to the level priority. During the whole process, it is only necessary to obtain the SOC value of the battery cell in the target battery system and perform simple calculations, which simplifies the battery system SOC value balancing strategy and is easy to implement. At the same time, by charging or discharging the battery cells in the balancing level according to the level priority, the balancing efficiency can be improved.

[0006] In one embodiment, judging whether the target battery system has a SOC balancing requirement based on the maximum SOC value, the minimum SOC value and the SOC mean value in the target battery system includes: calculating the SOC mean value of the target battery system based on the SOC values ​​of each battery cell in the target battery system; determining that the absolute value of the difference between the maximum SOC value and the SOC mean value is a first difference; determining that the absolute value of the difference between the minimum SOC value and the SOC mean value is a second difference; and judging whether the target battery system has a SOC balancing requirement based on the relationship between the first difference and the second difference and a difference threshold value, respectively.

[0007] In the above implementation process, the absolute value of the difference between the maximum SOC value and the minimum SOC value of the cells in the target battery system and the SOC mean is used to determine whether the target battery system has a SOC balancing requirement. The entire judgment strategy only includes simple addition and subtraction calculations and size judgments, and the implementation method is simple, which greatly simplifies the judgment strategy.

[0008] In one embodiment, the SOC balancing requirement includes: discharge balancing; if it is determined that the target battery system has an SOC balancing requirement, determining the balancing level of each battery cell according to the minimum SOC value and the SOC value of each battery cell in the target battery system, including: respectively calculating the discharge difference between the SOC value of each battery cell in the target battery system and the minimum SOC value; determining the balancing level of each battery cell according to the relationship between the discharge difference of each battery cell and a discharge difference threshold; wherein the discharge difference threshold includes one or more thresholds.

[0009] In the above implementation process, by setting the discharge difference threshold, and according to the relationship between the discharge difference between the SOC value of each cell and the minimum SOC value and the discharge difference threshold, the cells are divided into balance levels. The entire division process only requires simple addition and subtraction calculations and size judgments, and the implementation method is simple, which greatly simplifies the division strategy. In addition, by dividing the cells into balance levels according to the relationship between the discharge difference and the discharge difference threshold, when discharging the cells, they can be discharged in the order of the discharge difference of the cells, and the cells with larger discharge differences are discharged first, thereby improving the overall discharge efficiency of the target battery system.

[0010] In one embodiment, the discharge difference threshold includes: a first discharge difference threshold, a second discharge difference threshold and a third discharge difference threshold; the first discharge difference threshold is greater than the second discharge difference threshold and greater than the third discharge difference threshold; the determining the balance level to which each battery cell belongs according to the relationship between the discharge difference of each battery cell and the discharge difference threshold includes: determining that the battery cell whose discharge difference is greater than the first discharge difference threshold belongs to the first discharge balance level; determining that the battery cell whose discharge difference is less than or equal to the first discharge difference threshold and greater than the second discharge difference threshold belongs to the second discharge balance level; determining that the battery cell whose discharge difference is less than or equal to the second discharge difference threshold and greater than the third discharge difference threshold belongs to the third discharge balance level; wherein the discharge priority of the first discharge balance level is greater than the second discharge balance level, and the discharge priority of the second discharge balance level is greater than the third discharge balance level.

[0011] In the above implementation process, since the first discharge balancing level mainly includes a portion of cells with the largest discharge difference in the target battery system, the second discharge balancing level mainly includes a portion of cells with a medium discharge difference in the target battery system, and the third discharge balancing level mainly includes a portion of cells with a small discharge difference in the target battery system. By setting the discharge priority of the first discharge balancing level to be greater than the second discharge balancing level, and the discharge priority of the second discharge balancing level to be greater than the third discharge balancing level, the cells in the target battery system are discharged in the order of the discharge difference from large to small, and the cells that have a greater impact on the SOC value balance of the target battery system can be balanced first, thereby improving the overall balancing efficiency of the target battery system.

[0012] In one embodiment, the SOC balancing requirement includes: charging balancing; if it is determined that the target battery system has an SOC balancing requirement, determining the balancing level of each battery cell according to the maximum SOC value and the SOC value of each battery cell in the target battery system, including: calculating the charging difference between the SOC value of each battery cell in the target battery system and the maximum SOC value respectively; determining the balancing level of each battery cell according to the relationship between the charging difference of each battery cell and a charging difference threshold; wherein the charging difference threshold is one or more.

[0013] In the above implementation process, by setting the charge difference threshold, and according to the relationship between the charge difference between the SOC value of each cell and the maximum SOC value and the charge difference threshold, the cells are divided into balance levels. The entire division process only requires simple addition and subtraction calculations and size judgments, and the implementation method is simple, which greatly simplifies the division strategy. In addition, by dividing the cells into balance levels according to the relationship between the charge difference and the charge difference threshold, when charging the cells, the cells can be charged in the order of the charge difference size, and the cells with larger charge differences are charged first, thereby improving the overall charging efficiency of the target battery system.

[0014] In one embodiment, the charging difference threshold includes: a first charging difference threshold, a second charging difference threshold and a third charging difference threshold; the first charging difference threshold is greater than the second charging difference threshold and greater than the third charging difference threshold; the determining the equalization level to which the respective battery cells belong according to the relationship between the charging difference of the respective battery cells and the charging difference threshold includes: determining that the battery cells whose charging difference is greater than the first charging difference threshold belong to the first charging equalization level; determining that the battery cells whose charging difference is less than or equal to the first charging difference threshold and greater than the second charging difference threshold belong to the second charging equalization level; determining that the battery cells whose charging difference is less than or equal to the second charging difference threshold and greater than the third charging difference threshold belong to the third charging equalization level; wherein the charging priority of the first charging equalization level is greater than that of the second charging equalization level, and the charging priority of the second charging equalization level is greater than that of the third charging equalization level.

[0015] In the above implementation process, since the first charge equalization level mainly includes a portion of cells with the largest charge difference in the target battery system, the second charge equalization level mainly includes a portion of cells with a medium charge difference in the target battery system, and the third charge equalization level mainly includes a portion of cells with a small charge difference in the target battery system, by setting the charging priority of the first charge equalization level to be greater than the second charge equalization level, and the charging priority of the second charge equalization level to be greater than the third charge equalization level, the cells in the target battery system are charged in descending order of the charge difference, and the cells that have a greater impact on the SOC value balance of the target battery system can be balanced first, thereby improving the overall balance efficiency of the target battery system.

[0016] In one embodiment, charging or discharging the battery cells in each balancing level in order of level priority includes: determining, for each balancing level, a charging difference between the SOC value of each battery cell in the balancing level and the maximum SOC value, or a discharging difference between the SOC value of each battery cell in the balancing level and the minimum SOC value; and charging or discharging each battery cell in the balancing level in order from large to small according to the charging difference or the discharging difference.

[0017] In the above implementation process, the battery cells in each balancing level are discharged in the order of discharge difference from large to small, or charged in the order of charge difference from large to small. The battery cells that have a greater impact on the SOC value balancing of the target battery system can be balanced first, thereby improving the overall balancing efficiency of the target battery system.

[0018] In a second aspect, an embodiment of the present application further provides a battery system, comprising: a battery cell module, a switch array, a DCDC module, a control module and a battery management system; each battery cell in the battery cell module is connected to the DCDC module through a switch in the corresponding switch array, and the DCDC module is also connected to an external power system and an external power supply; the DCDC module is configured to transmit the electric energy of the battery cell with discharge demand to the external power system for use by the external power system, or to transmit the electric energy of the external power supply to the battery cell with charging demand for charging the battery cell with charging demand; the control module is connected to the DCDC module block, the switches in the switch array and the battery management system, the control module is configured to obtain the electrical parameters of each battery cell in the battery cell module, and send the electrical parameters to the battery management system; wherein the battery management system is configured to execute the above-mentioned first aspect, or the battery system active SOC balancing method in any possible implementation of the first aspect to obtain the charge and discharge control instructions of each battery cell in the battery cell module, and send the same to the control module; the control module controls the opening or closing of each switch in the switch array according to the charge and discharge control instructions, and controls the DCDC module to perform SOC balancing.

[0019] In the above implementation process, by setting the first switch group and the second switch group, the first switch group is used to connect the two ends of the battery cell to achieve connection with all the battery cells. The second switch group connects the first switch group and the DCDC module. The second switch group is used to classify and combine multiple switches in the first switch group and connect them, and lead out fewer wiring harnesses to connect with the DCDC module, which can reduce the wiring harness between the switch array and the DCDC module, thereby reducing the wiring cost and wiring difficulty in the battery system.

[0020] In one embodiment, the switch array includes a first switch group and a second switch group; one end of each switch in the first switch group is connected to each battery cell in the battery cell module; the second switch group is connected to the DCDC module and the other end of each switch in the first switch group.

[0021] In the above implementation process, by setting the first switch group and the second switch group, the first switch group is used to connect the two ends of the battery cell to achieve connection with all the battery cells. The second switch group connects the first switch group and the DCDC module. The second switch group is used to classify and combine multiple switches in the first switch group and connect them, and lead out fewer wiring harnesses to connect with the DCDC module, which can reduce the wiring harness between the switch array and the DCDC module, thereby reducing the wiring cost and wiring difficulty in the battery system.

[0022] In one embodiment, the second switch group includes a first switch, a second switch, a third switch and a fourth switch; the switches in the first switch group are numbered in a setting order, namely odd-numbered switches and even-numbered switches; one end of the first switch is connected to one end of the second switch, and the other end of the first switch is connected to one end of the fourth switch; one end of the third switch is connected to the other end of the second switch, and the other end of the third switch is connected to the other end of the fourth switch; the ends of the odd-numbered switches away from the battery cells are connected in parallel with each other and connected to the ends connected with the first switch and the second switch; the ends of the even-numbered switches away from the battery cells are connected in parallel with each other and connected to the ends connected with the third switch and the fourth switch; the end connected with the first switch and the fourth switch is connected to the first power interface of the DCDC module, and the end connected with the second switch and the third switch is connected to the second power interface of the DCDC module.

[0023] In the above implementation process, the first positions of each switch in the second switch group are connected in sequence to obtain four series connection lines, and the first power interface and the second power interface of the DCDC module are respectively connected to two opposite connection lines. At the same time, the switches in the first switch group are classified into odd and even numbers according to their numbers. After the ends of the switches with the same numbers away from the battery cells are short-circuited, two connection lines are formed, and the two connection lines are respectively connected to the other two opposite connection lines, so that the first switch group and the second switch group can be flexibly connected, thereby reducing the wiring harness layout and cost of the battery system and improving the flexibility of the switch array setting.

[0024] In a third aspect, an embodiment of the present application further provides a battery management system, comprising: a processor and a memory, wherein the memory stores machine-readable instructions executable by the processor, and when the battery management system is running, the machine-readable instructions are executed by the processor to perform the steps of the method in the above-mentioned first aspect, or any possible implementation of the first aspect.

[0025] In order to make the above-mentioned objects, features and advantages of the present application more obvious and understandable, embodiments are given below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A schematic diagram of a battery system circuit provided in an embodiment of the present application; Figure 2 A block diagram of a battery management system provided in an embodiment of the present application; Figure 3 A schematic diagram of a switch array provided in an embodiment of the present application; Figure 4 An example diagram of the connection between the first switch group and the second switch group provided in an embodiment of the present application; Figure 5 A flow chart of a method for active SOC balancing of a battery system provided in an embodiment of the present application.

[0028] Description of the drawings: 100 - battery management system, 111 - memory, 113 - processor, 200 - battery cell module, 210 - battery cell, 300 - switch array, 310 - first switch group, 320 - second switch group, 400 - DCDC module, 500 - control module, K1 - first switch, K2 - second switch, K3 - third switch, K4 - fourth switch, 20 - external power system, 30 - external power supply. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings in the embodiments of the present application.

[0030] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0031] During the charging and discharging process, the battery system will terminate with high charging and low discharging. The difference between cells affects the system's usage capacity. In order to fully utilize the battery system capacity, it is necessary to ensure the consistency between cells. Usually, the battery system needs to be SOC balanced.

[0032] Currently, common methods of SOC balancing for battery systems include passive balancing and active balancing. Among them, passive balancing is energy consumption type, that is, using balancing resistors to consume part of the energy. Active balancing is energy transfer type, that is, achieving balancing through energy transfer between cells.

[0033] The inventor of the present application has found through long-term research that in the passive balancing method, energy is directly consumed by the balancing resistor, resulting in reduced energy utilization. In the active balancing method, since energy conversion between cells needs to be achieved, the circuit is more complex, the stability is relatively low, and the cost is higher.

[0034] In view of this, the present application proposes an active SOC balancing method for a battery system. By connecting the battery cells to an external power supply and an external power consumer, the battery cells in the battery system can be charged and balanced by the external power supply, or the energy of the battery cells in the battery system can be consumed by the external power consumer to achieve discharge balancing of the battery system. While achieving energy balancing in the battery system, the redundant electric energy in the battery system can be fully utilized to improve energy utilization. In addition, when performing energy balancing, the target battery system balancing demand judgment and battery cell level division are directly performed based on the SOC value of the battery cells in the target battery system, and then the battery cells in the balancing level are charged or discharged according to the level priority. In the whole process, it is only necessary to obtain the SOC value of the battery cells in the target battery system and perform simple calculations, which simplifies the battery system SOC value balancing strategy and is easy to implement. At the same time, by charging or discharging the battery cells in the balancing level according to the level priority, the balancing efficiency can be improved.

[0035] To facilitate understanding of this embodiment, a battery system disclosed in an embodiment of the present application is first introduced in detail.

[0036] like Figure 1 , which is a schematic diagram of a battery system circuit. The battery system includes: a battery cell module 200 , a switch array 300 , a DCDC module 400 , a control module 500 and a battery management system 100 .

[0037] Among them, each battery cell 210 in each battery cell module 200 is connected to the DCDC module 400 through the switch in the corresponding switch array 300, and the DCDC module 400 is also connected to the external power system 20 and the external power supply 30; the control module 500 is connected to the DCDC module 400, the switch in the switch array 300 and the battery management system 100.

[0038] The battery system here includes one or more battery modules 200, and each battery module 200 includes one or more battery cells 210. The two ends of each battery cell 210 are respectively connected to a switch in the switch array 300.

[0039] It should be understood that there is usually a certain difference in the SOC value of each single cell 210 in the battery system. In order to improve the consistency of each single cell 210 in the battery system, it is usually necessary to perform energy balancing on each single cell 210 in the battery system. The energy balancing of the cell 210 can be achieved by charging or discharging.

[0040] The control module 500 is configured to control the DCDC module 400 to perform SOC balancing. The DCDC module 400 is configured to transmit the electric energy of the battery cell 210 with discharge demand to the external power system 20 for use by the external power system 20. Or transmit the electric energy of the external power source 30 to the battery cell 210 with charging demand for charging the battery cell 210 with charging demand.

[0041] In one embodiment, the external power system 20 may be a power device in a low voltage system (e.g., a 12V system, a 24V system) in the vehicle. For example, a domain controller, an electronic control unit, an onboard computer, a navigator, etc. The external power device may be selected according to actual conditions. The external power source 30 may be a power supply unit, a backup power supply, etc. in a low voltage system, and the external power source 30 may be selected according to actual conditions.

[0042] The control module 500 here is configured to obtain the electrical parameters of each battery cell 210 in the battery cell module 200 and send the electrical parameters to the battery management system 100. The electrical parameters may include the voltage, remaining capacity, rated capacity, etc. of the battery cell 210. The electrical parameters may be selected according to actual conditions.

[0043] Among them, the battery management system 100 is configured to execute the battery system active SOC balancing method to obtain the charge and discharge control instructions of each battery cell 210 in the battery cell module 200, and send them to the control module 500; the control module 500 controls each switch in the switch array 300 to open or close according to the charge and discharge control instructions.

[0044] The battery management system 100 can be used to determine whether the battery system has a SOC balancing requirement based on the electrical parameters of each battery cell 210 sent by the control module 500, and when the battery system has a SOC balancing requirement, calculate the balancing level of each battery cell 210. Then, control instructions for each corresponding switch are generated based on the balancing level of each battery cell 210, and the control instructions are sent to the control module 500.

[0045] In one embodiment, if Figure 2 , which is a block diagram of a battery management system 100. The battery management system 100 may include a memory 111 and a processor 113. A person skilled in the art may understand that Figure 2The structure shown is only for illustration and does not limit the structure of the battery management system 100. For example, the battery management system 100 may also include Figure 2 More or fewer components as shown, or with Figure 2 Different configurations are shown.

[0046] The memory 111 and the processor 113 are directly or indirectly electrically connected to each other to achieve data transmission or interaction. For example, these elements can be electrically connected to each other via one or more communication buses or signal lines. The processor 113 is used to execute the executable module stored in the memory.

[0047] The memory 111 may be, but is not limited to, a random access memory (RAM), a read only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable read-only memory (EEPROM), etc. The memory 111 is used to store programs, and the processor 113 executes the program after receiving the execution instruction. The method executed by the battery management system 100 defined by the process disclosed in any embodiment of the present application can be applied to the processor 113, or implemented by the processor 113.

[0048] The processor 113 may be an integrated circuit chip with signal processing capability. The processor 113 may be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it may also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps and logic block diagrams disclosed in the embodiments of the present application may be implemented or executed. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0049] In the above implementation process, by connecting the battery cell 210 to the external power source 30 and the external power-consuming device, the battery cells 210 in the battery system can be charged and balanced by the external power source 30, or the energy of the battery cells 210 in the battery system can be consumed by the external power-consuming device to achieve discharge balance of the battery system. While achieving energy balance in the battery system, the redundant power in the battery system can be fully utilized to improve energy utilization.

[0050] In one possible implementation, Figure 3 As shown, the switch array 300 includes a first switch group 310 and a second switch group 320 .

[0051] One end of each switch in the first switch group 310 is connected to one end of each battery cell 210 in the battery cell module 200 ; and the second switch group 320 is connected to the DCDC module 400 and the other end of each switch in the first switch group 310 .

[0052] Both ends of each battery cell 210 in the battery system are respectively connected to a switch in the first switch group 310. The number of switches in the first switch group 310 is determined by the number of battery cells 210 in the battery system.

[0053] In one embodiment, two adjacent battery cells 210 share a switch at their respective ends.

[0054] It should be understood that the DCDC module 400 refers to a device that converts a DC voltage into a specific output DC voltage. For the DCDC module 400, both the input and output ends are provided with a positive power interface and a negative power interface. Therefore, when a certain battery cell 210 needs to be charged or discharged, it needs to be connected in parallel with the DCDC module 400. That is, the two ends of the battery cell 210 need to be connected to the positive power interface and the negative power interface of the DCDC module 400, respectively. If the other ends of the switches connected to both ends of all battery cells 210 are connected to the positive power interface and the negative power interface of the DCDC module 400, the positive power interface and the negative power interface of the DCDC module 400 will be connected to too many wiring harnesses, and the interface pressure is relatively large.

[0055] The switches in the second switch group 320 are used to connect the first switch group 310 and the DCDC module 400, so as to integrate the other end of the switch in the first switch group 310, and lead out a connecting line to the positive power interface and the negative power interface of the DCDC module 400 respectively, thereby reducing the wiring harness to which both the positive power interface and the negative power interface of the DCDC module 400 are connected.

[0056] The switches in the second switch group 320 may be used to switch the switches in the first switch group 310 connected to the DCDC module 400 .

[0057] In the above implementation process, by setting the first switch group 310 and the second switch group 320, the first switch group 310 is used to connect the two ends of the battery cell 210 to achieve connection with all the battery cells 210. The second switch group 320 connects the first switch group 310 and the DCDC module 400. The second switch group 320 is used to classify and combine multiple switches in the first switch group 310 and connect them with fewer wiring harnesses connected to the DCDC module 400, which can reduce the wiring harness between the switch array 300 and the DCDC module 400, thereby reducing the wiring cost and wiring difficulty in the battery system.

[0058] In one possible implementation, Figure 4 As shown, the second switch group 320 includes a first switch K1, a second switch K2, a third switch K3 and a fourth switch K4; the switches in the first switch group 310 are numbered according to a setting sequence, namely odd-numbered switches and even-numbered switches.

[0059] Among them, one end of the first switch K1 is connected to one end of the second switch K2, and the other end of the first switch K1 is connected to one end of the fourth switch K4; one end of the third switch K3 is connected to the other end of the second switch K2, and the other end of the third switch K3 is connected to the other end of the fourth switch K4; one end of the odd-numbered switches away from the battery cell 210 is connected in parallel to each other and connected to the first connecting line in the second switch group 320; one end of the even-numbered switches away from the battery cell 210 is connected in parallel to each other and connected to the third connecting line in the second switch group 320; the second connecting line in the second switch group 320 is connected to the first power interface of the DCDC module 400, and the fourth connecting line in the second switch group 320 is connected to the second power interface of the DCDC module 400.

[0060] Here, the first connection line and the third connection line are relative connection lines, the second connection line and the fourth connection line are relative connection lines, and the second connection line and the fourth connection line are both adjacent connection lines to the first connection line and the third connection line.

[0061] The first connecting line, the second connecting line, the third connecting line and the fourth connecting line may include the following configurations: Mode 1: The first connection line is the connection line between the third switch K3 and the fourth switch K4, the second connection line is the connection line between the first switch K1 and the fourth switch K4, the third connection line is the connection line between the first switch K1 and the second switch K2, and the fourth connection line is the connection line between the second switch K2 and the third switch K3.

[0062] Mode 2: The first connection line is a connection line between the third switch K3 and the fourth switch K4, the second connection line is a connection line between the second switch K2 and the third switch K3, the third connection line is a connection line between the first switch K1 and the second switch K2, and the fourth connection line is a connection line between the first switch K1 and the fourth switch K4.

[0063] Mode 3: The first connection line is a connection line between the first switch K1 and the second switch K2, the second connection line is a connection line between the first switch K1 and the fourth switch K4, the third connection line is a connection line between the third switch K3 and the fourth switch K4, and the fourth connection line is a connection line between the second switch K2 and the third switch K3.

[0064] Mode 4: The first connection line is a connection line between the first switch K1 and the second switch K2, the second connection line is a connection line between the second switch K2 and the third switch K3, the third connection line is a connection line between the third switch K3 and the fourth switch K4, and the fourth connection line is a connection line between the first switch K1 and the fourth switch K4.

[0065] Mode 5: The first connection line is a connection line between the first switch K1 and the fourth switch K4, the second connection line is a connection line between the third switch K3 and the fourth switch K4, the third connection line is a connection line between the second switch K2 and the third switch K3, and the fourth connection line is a connection line between the first switch K1 and the second switch K2.

[0066] Mode 6: The first connection line is a connection line between the first switch K1 and the fourth switch K4, the second connection line is a connection line between the first switch K1 and the second switch K2, the third connection line is a connection line between the second switch K2 and the third switch K3, and the fourth connection line is a connection line between the third switch K3 and the fourth switch K4.

[0067] Mode 7: The first connection line is a connection line between the second switch K2 and the third switch K3, the second connection line is a connection line between the third switch K3 and the fourth switch K4, the third connection line is a connection line between the first switch K1 and the fourth switch K4, and the fourth connection line is a connection line between the first switch K1 and the second switch K2.

[0068] Mode 8: The first connection line is a connection line between the second switch K2 and the third switch K3, the second connection line is a connection line between the first switch K1 and the second switch K2, the third connection line is a connection line between the first switch K1 and the fourth switch K4, and the fourth connection line is a connection line between the third switch K3 and the fourth switch K4.

[0069] The above-mentioned arrangement of the first connection line, the second connection line, the third connection line and the fourth connection line is only exemplary, and the arrangement of the first connection line, the second connection line, the third connection line and the fourth connection line can be adjusted according to actual conditions.

[0070] It should be understood that the multiple battery cells 210 in each battery module are connected in series in a set order. Every two switches in the first switch group 310 are respectively connected in parallel to the two ends of each battery cell 210. Among them, the numbers of all switches in the first switch group 310 connected to the positive pole of the battery cell 210 can be the same even number or the same odd number. The numbers of all switches in the first switch group 310 connected to the negative pole of the battery cell 210 can be the same even number or the same odd number. The parity of the switches connected to the two ends of the same battery cell 210 is different.

[0071] For example, Figure 4 As shown, the switches S0, S2, S4, ... SN-1 connected to the negative pole of each switch in the first switch group 310 are all even-numbered switches. The switches S1, S3, S5, ... SN connected to the positive pole of each switch in the first switch group 310 are all odd-numbered switches. Wherein, N is an odd number.

[0072] Each battery cell 210 in the battery system can also be numbered according to a set sequence. The battery cell 210 sequence number can also be divided into an even number sequence number and an odd number sequence number.

[0073] It can be understood that the specific control process of the switches in the first switch group 310 and the second switch group 320 in the switch array 300 can be as follows: In the initialization phase, all switches in the switch array 300 are disconnected. When performing SOC balancing of the battery system, the control module 500 determines whether there is a balancing requirement for the battery system according to the control instruction sent by the battery management system 100. If there is a balancing requirement for the battery system, and the serial number of the battery cell 210 that needs to be balanced is X, the two switches in the first switch group 310 connected to both ends of the battery cell 210 are controlled to be closed. And determine whether the serial number X is an odd serial number or an even serial number, so as to control the switch in the second switch group 320 to be closed according to the serial number of the battery cell 210.

[0074] For example, Figure 4 As shown, Figure 4 It is shown that the ends of the odd-numbered switches away from the battery cell 210 are connected in parallel to each other and connected to the ends of the first switch K1 and the second switch K2; the ends of the even-numbered switches away from the battery cell 210 are connected in parallel to each other and connected to the ends of the third switch K3 and the fourth switch K4; the ends of the first switch K1 and the fourth switch K4 are connected to the first power interface of the DCDC module 400, and the ends of the second switch K2 and the third switch K3 are connected to the second power interface of the DCDC module 400. Figure 4 In the switch array 300 shown, if the sequence number X is an odd number, the second switch K2 and the fourth switch K4 in the second switch group 320 are controlled to be closed. If the sequence number X is an even number, the first switch K1 and the third switch K3 in the second switch group 320 are controlled to be closed.

[0075] like Figure 4 As shown, Figure 4 It is shown that the ends of the odd-numbered switches away from the battery cell 210 are connected in parallel to each other and connected to the ends connected to the third switch K3 and the fourth switch K4; the ends of the even-numbered switches away from the battery cell 210 are connected in parallel to each other and connected to the ends connected to the first switch K1 and the second switch K2; the ends connected to the first switch K1 and the fourth switch K4 are connected to the first power interface of the DCDC module 400, and the ends connected to the second switch K2 and the third switch K3 are connected to the second power interface of the DCDC module 400. Figure 4 In the switch array 300 shown, if the sequence number X is an odd number, the first switch K1 and the third switch K3 in the second switch group 320 are controlled to be closed. If the sequence number X is an even number, the second switch K2 and the fourth switch K4 in the second switch group 320 are controlled to be closed.

[0076] In the above implementation process, the first positions of each switch in the second switch group 320 are connected in sequence to obtain four series connection lines, and the first power interface and the second power interface of the DCDC module 400 are respectively connected to two opposite connection lines. At the same time, the switches in the first switch group 310 are classified into odd and even numbers according to the numbers. After the ends of the switches with the same numbers away from the battery cell 210 are short-circuited, two connection lines are formed, and the two connection lines are respectively connected to the other two opposite connection lines, so that the first switch group 310 and the second switch group 320 can be flexibly connected, thereby reducing the wiring harness layout and cost of the battery system and improving the setting flexibility of the switch array 300.

[0077] The battery management system 100 in this embodiment can be used to execute each step in each method provided in the embodiments of the present application. The implementation process of the active SOC balancing method for the battery system is described in detail below through several embodiments.

[0078] See also Figure 5 , is a flow chart of the active SOC balancing method for a battery system provided in an embodiment of the present application. Figure 5 The specific process shown is described in detail.

[0079] Step S201 , judging whether there is a SOC balancing requirement for the target battery system according to the maximum SOC value, the minimum SOC value and the SOC mean value in the target battery system.

[0080] Among them, the maximum SOC value in the target battery system is the largest SOC value among the SOC values ​​of each battery cell in the target battery system, the minimum SOC value is the smallest SOC value among the SOC values ​​of each battery cell in the target battery system, and the SOC mean is the average SOC value of each battery cell in the target battery system.

[0081] In one embodiment, after obtaining the SOC value of each battery cell in the target battery system, the battery management system sorts the SOC value of each battery cell in the target battery system from large to small or from small to large, and then determines the maximum SOC value and the minimum SOC value.

[0082] In addition, the battery management system can also determine the SOC mean value based on the quotient of the sum of the SOC values ​​of the individual cells and the number of cells in the target battery system.

[0083] It should be understood that when the SOC value of the battery cells in the target battery system is significantly different from the SOC average value, it can be considered that the SOC values ​​of the battery cells in the target battery system are unbalanced, and the SOC of each battery cell needs to be balanced.

[0084] The SOC balancing requirements here include charging balancing and discharging balancing.

[0085] Step S202: If it is determined that the target battery system has an SOC balancing requirement, then the balancing level of each battery cell is determined according to the maximum SOC value or the minimum SOC value and the SOC value of each battery cell in the target battery system.

[0086] The balancing level here can be determined according to the absolute value of the difference between the SOC value of each battery cell and the maximum SOC value or the minimum SOC value. The balancing level may include one or more levels.

[0087] It should be understood that when the SOC balancing requirement is discharge balancing, the cells in the target battery system need to be discharged. Since the minimum SOC value is the cell with the smallest SOC value in the target battery system, it is usually not necessary to discharge it again. In this case, the minimum SOC value can be used as a reference SOC value so that the absolute value of the difference between the SOC value of other cells in the target battery system after discharge and the minimum SOC value is within the allowable range. That is, when the SOC balancing requirement is discharge balancing, the balancing level can be determined based on the absolute value of the difference between the SOC value of each cell and the minimum SOC value.

[0088] Similarly, when the SOC balancing requirement is charge balancing, the cells in the target battery system need to be charged. Since the maximum SOC value is the cell with the largest SOC value in the target battery system, it usually does not need to be recharged. In this case, the maximum SOC value can be used as a reference SOC value so that the absolute value of the difference between the SOC value of other cells in the target battery system after charging and the maximum SOC value is within the allowable range. That is, when the SOC balancing requirement is charge balancing, the balancing level can be determined based on the absolute value of the difference between the SOC value of each cell and the maximum SOC value.

[0089] Step S203 , charging or discharging the cells in each balancing level respectively according to the level priority order, so as to balance the SOC value of each cell in the target battery system.

[0090] It can be understood that, whether it is charging demand or discharging demand, the greater the absolute value of the difference between the SOC value of the battery cell and the maximum SOC value or the minimum SOC value, the greater the impact on the SOC value consistency of the target battery system. Therefore, when performing charge balancing or discharge balancing, the battery cell with the absolute value of the difference can be charged or discharged first to improve the overall balancing efficiency of the target battery system.

[0091] In the above implementation process, the target battery system balancing demand is directly determined based on the SOC value of the battery cell in the target battery system, and the battery cell level is divided, and then the battery cells in the balancing level are charged or discharged according to the level priority. During the whole process, it is only necessary to obtain the SOC value of the battery cell in the target battery system and perform simple calculations, which simplifies the battery system SOC value balancing strategy and is easy to implement. At the same time, by charging or discharging the battery cells in the balancing level according to the level priority, the balancing efficiency can be improved.

[0092] In a possible implementation, step S202 includes: calculating the SOC mean of the target battery system according to the SOC values ​​of each battery cell in the target battery system; determining the absolute value of the difference between the maximum SOC value and the SOC mean as a first difference; determining the absolute value of the difference between the minimum SOC value and the SOC mean as a second difference; and judging whether there is a SOC balancing requirement for the target battery system according to the relationship between the first difference and the second difference and the difference threshold, respectively.

[0093] The average SOC value here can be obtained by dividing the SOC value of all cells in the target battery system by the total number of cells.

[0094] The above difference threshold is the maximum value of the SOC value difference between the cells allowed by the target battery system. The difference threshold can be determined according to the properties of the target battery system, the properties of the cells in the target battery system, and the function of the target battery system. The difference threshold can be set according to actual conditions.

[0095] It should be understood that if the first difference or the second difference exceeds the difference threshold, it means that the SOC values ​​between the cells in the target battery system differ greatly and SOC value balancing is required. If the first difference and the second difference are both within the difference threshold, it means that the difference between the SOC values ​​between the cells in the target battery system is within the allowable range and SOC value balancing is not required.

[0096] In an embodiment, after determining that the target battery system has a balancing requirement, the type of SOC balancing requirement may be determined according to the first difference and the second difference.

[0097] If the first difference is greater than or equal to the second difference, the SOC balancing requirement is a discharging requirement, and if the first difference is less than the second difference, the SOC balancing requirement is a charging requirement.

[0098] In the above implementation process, the absolute value of the difference between the maximum SOC value and the minimum SOC value of the cells in the target battery system and the SOC mean is used to determine whether the target battery system has a SOC balancing requirement. The entire judgment strategy only includes simple addition and subtraction calculations and size judgments, and the implementation method is simple, which greatly simplifies the judgment strategy.

[0099] In a possible implementation, step S202 includes: calculating the discharge difference between the SOC value of each battery cell in the target battery system and the minimum SOC value; and determining the balancing level of each battery cell according to the relationship between the discharge difference of each battery cell and the discharge difference threshold.

[0100] The above-mentioned discharge difference threshold may include one or more thresholds. For example, the discharge difference threshold includes four thresholds B1, B2, B3, and B4, the discharge difference threshold includes three thresholds B1, B2, and B3, the discharge difference threshold includes two thresholds B1 and B2, the discharge difference threshold includes five thresholds B1, B2, B3, B4, and B5, etc. The number and specific values ​​of the discharge difference thresholds can be selected according to actual conditions.

[0101] In one embodiment, the discharge difference threshold includes: a first discharge difference threshold, a second discharge difference threshold and a third discharge difference threshold; the first discharge difference threshold is greater than the second discharge difference threshold and greater than the third discharge difference threshold.

[0102] In the above implementation process, by setting the discharge difference threshold, and according to the relationship between the discharge difference between the SOC value of each cell and the minimum SOC value and the discharge difference threshold, the cells are divided into balance levels. The entire division process only requires simple addition and subtraction calculations and size judgments, and the implementation method is simple, which greatly simplifies the division strategy. In addition, by dividing the cells into balance levels according to the relationship between the discharge difference and the discharge difference threshold, when discharging the cells, they can be discharged in the order of the discharge difference of the cells, and the cells with larger discharge differences are discharged first, thereby improving the overall discharge efficiency of the target battery system.

[0103] In a possible implementation, the balance level of each battery cell is determined according to the relationship between the discharge difference of each battery cell and the discharge difference threshold, including: determining that a battery cell whose discharge difference is greater than a first discharge difference threshold belongs to a first discharge balance level; determining that a battery cell whose discharge difference is less than or equal to the first discharge difference threshold and greater than the second discharge difference threshold belongs to a second discharge balance level; determining that a battery cell whose discharge difference is less than or equal to the second discharge difference threshold and greater than the third discharge difference threshold belongs to a third discharge balance level.

[0104] The discharge priority of the first discharge balancing level is greater than that of the second discharge balancing level, and the discharge priority of the second discharge balancing level is greater than that of the third discharge balancing level.

[0105] Specifically, when performing discharge balancing, discharging each cell in the battery system according to the discharge priorities of the first discharge balancing level, the second discharge balancing level, and the third discharge balancing level can be achieved in the following ways: Method 1: When performing discharge balancing, a group of cells with a high discharge priority (i.e., cells in the first discharge balancing level) can be balanced first, and all cells in the first discharge balancing level are discharged until the discharge difference is less than the first discharge difference threshold. At this time, the balancing level to which the cells of the original first discharge balancing level belong is changed to the second discharge balancing level, and then the cells of the next discharge priority (i.e., cells in the original first discharge balancing level and the original second discharge balancing level) are balanced, and all cells in the original first discharge balancing level and the original second discharge balancing level are discharged until the discharge difference is less than the second discharge difference threshold. At this time, the balancing level to which the cells of the original first discharge balancing level and the original second discharge balancing level belong is changed to the third discharge balancing level, and then the cells of the next discharge priority (i.e., cells in the original first discharge balancing level, the original second discharge balancing level, and the original third discharge balancing level) are balanced, and all cells in the original first discharge balancing level, the original second discharge balancing level, and the original third discharge balancing level are discharged until the discharge difference is less than the third discharge difference threshold. Method 2: When performing discharge balancing, a group of cells with a high discharge priority (i.e., cells in the first discharge balancing level) may be balanced first, and all cells in the first discharge balancing level may be discharged until the discharge difference is less than the third discharge difference threshold. Then, cells with the next discharge priority (i.e., cells in the second discharge balancing level) may be balanced, and all cells in the second discharge balancing level may be discharged until the discharge difference is less than the third discharge difference threshold. Then, cells with the next discharge priority (i.e., cells in the third discharge balancing level) may be balanced, and all cells in the third discharge balancing level may be discharged until the discharge difference is less than the third discharge difference threshold.

[0106] The discharge modes of the cells in the first discharge balance level, the second discharge balance level and the third discharge balance level are only exemplary, and the specific discharge modes of the first discharge balance level, the second discharge balance level and the third discharge balance level can be selected according to actual conditions.

[0107] In the above implementation process, since the first discharge balancing level mainly includes a portion of cells with the largest discharge difference in the target battery system, the second discharge balancing level mainly includes a portion of cells with a medium discharge difference in the target battery system, and the third discharge balancing level mainly includes a portion of cells with a small discharge difference in the target battery system. By setting the discharge priority of the first discharge balancing level to be greater than the second discharge balancing level, and the discharge priority of the second discharge balancing level to be greater than the third discharge balancing level, the cells in the target battery system are discharged in the order of the discharge difference from large to small, and the cells that have a greater impact on the SOC value balance of the target battery system can be balanced first, thereby improving the overall balancing efficiency of the target battery system.

[0108] In a possible implementation, step S202 includes: respectively calculating the charging difference between the SOC value of each battery cell in the target battery system and the maximum SOC value; and determining the balancing level of each battery cell according to the relationship between the charging difference of each battery cell and the charging difference threshold.

[0109] The above-mentioned charge difference threshold is one or more. For example, the charge difference threshold includes four thresholds of A1, A2, A3, and A4, the charge difference threshold includes three thresholds of A1, A2, and A3, the charge difference threshold includes two thresholds of A1 and A2, the charge difference threshold includes five thresholds of A1, A2, A3, A4, and A5, etc. The number and specific values ​​of the charge difference thresholds can be selected according to actual conditions.

[0110] In one embodiment, the charging difference threshold includes: a first charging difference threshold, a second charging difference threshold and a third charging difference threshold; the first charging difference threshold is greater than the second charging difference threshold and greater than the third charging difference threshold.

[0111] In the above implementation process, by setting the charge difference threshold, and according to the relationship between the charge difference between the SOC value of each cell and the maximum SOC value and the charge difference threshold, the cells are divided into balance levels. The entire division process only requires simple addition and subtraction calculations and size judgments, and the implementation method is simple, which greatly simplifies the division strategy. In addition, by dividing the cells into balance levels according to the relationship between the charge difference and the charge difference threshold, when charging the cells, the cells can be charged in the order of the charge difference size, and the cells with larger charge differences are charged first, thereby improving the overall charging efficiency of the target battery system.

[0112] In a possible implementation, determining the balancing level of each battery cell according to the relationship between the charging difference of each battery cell and the charging difference threshold includes: determining that a battery cell whose charging difference is greater than a first charging difference threshold belongs to a first charging balancing level; determining that a battery cell whose charging difference is less than or equal to the first charging difference threshold and greater than the second charging difference threshold belongs to a second charging balancing level; and determining that a battery cell whose charging difference is less than or equal to the second charging difference threshold and greater than the third charging difference threshold belongs to a third charging balancing level.

[0113] The charging priority of the first charging equalization level is greater than that of the second charging equalization level, and the charging priority of the second charging equalization level is greater than that of the third charging equalization level.

[0114] Specifically, when performing charge balancing, charging each battery cell in the battery system according to the charging priorities of the first charge balancing level, the second charge balancing level, and the third charge balancing level can be achieved in the following ways: Method 1: When performing charge equalization, a group of cells with a high charge priority (i.e., cells in the first charge equalization level) can be equalized first, and all cells in the first charge equalization level are charged until the charge difference is less than the first charge difference threshold. At this time, the equalization level to which the cells of the original first charge equalization level belong is replaced with the second charge equalization level, and then the cells of the next charge priority (i.e., cells in the original first charge equalization level and the original second charge equalization level) are equalized, and all cells in the original first charge equalization level and the original second charge equalization level are charged until the charge difference is less than the second charge difference threshold. At this time, the equalization level to which the cells of the original first charge equalization level and the original second charge equalization level belong is replaced with the third charge equalization level, and then the cells of the next charge priority (i.e., cells in the original first charge equalization level, the original second charge equalization level, and the original third charge equalization level) are equalized, and all cells in the original first charge equalization level, the original second charge equalization level, and the original third charge equalization level are charged until the charge difference is less than the third charge difference threshold.

[0115] Method 2: When performing charge balancing, a group of cells with a high charge priority (i.e., cells in the first charge balancing level) may be balanced first, and all cells in the first charge balancing level may be charged until the charge difference is less than the third charge difference threshold. Then, cells with the next charge priority (i.e., cells in the second charge balancing level) may be balanced, and all cells in the second charge balancing level may be charged until the charge difference is less than the third charge difference threshold. Then, cells with the next charge priority (i.e., cells in the third charge balancing level) may be balanced, and all cells in the third charge balancing level may be charged until the charge difference is less than the third charge difference threshold.

[0116] The charging methods of the cells in the first charging equalization level, the second charging equalization level and the third charging equalization level are only exemplary, and the specific charging methods of the first charging equalization level, the second charging equalization level and the third charging equalization level can be selected according to actual conditions.

[0117] In the above implementation process, since the first charge equalization level mainly includes a portion of cells with the largest charge difference in the target battery system, the second charge equalization level mainly includes a portion of cells with a medium charge difference in the target battery system, and the third charge equalization level mainly includes a portion of cells with a small charge difference in the target battery system, by setting the charging priority of the first charge equalization level to be greater than the second charge equalization level, and the charging priority of the second charge equalization level to be greater than the third charge equalization level, the cells in the target battery system are charged in descending order of the charge difference, and the cells that have a greater impact on the SOC value balance of the target battery system can be balanced first, thereby improving the overall balance efficiency of the target battery system.

[0118] In a possible implementation, step S203 includes: for each balancing level, determining a charging difference between the SOC value of each battery cell in the balancing level and a maximum SOC value, or a discharging difference between the SOC value of each battery cell in the balancing level and a minimum SOC value; and charging or discharging each battery cell in the balancing level in descending order according to the charging difference or the discharging difference.

[0119] It should be understood that, whether it is charge equalization or discharge equalization, the greater the difference between the SOC value of the battery cell and the reference SOC value (i.e., the maximum SOC value or the minimum SOC value), the greater the impact on the equalization of the target battery system. If the battery cells that have a greater impact on the equalization of the target battery system are charged or discharged first, the imbalance of the target battery system can be gradually reduced, thereby narrowing the SOC value gap between the batteries in the target battery system.

[0120] In one embodiment, when the SOC balancing requirement is discharge balancing, the discharge difference between the SOC value of each battery cell in the balancing level and the minimum SOC value is determined; and each battery cell in the balancing level is discharged in order from large to small according to the discharge difference.

[0121] When the SOC balancing requirement is charging balancing, the charging difference between the SOC value of each battery cell in the balancing level and the minimum SOC value is determined; and each battery cell in the balancing level is charged in descending order according to the charging difference.

[0122] In the above implementation process, the battery cells in each balancing level are discharged in the order of discharge difference from large to small, or charged in the order of charge difference from large to small. The battery cells that have a greater impact on the SOC value balancing of the target battery system can be balanced first, thereby improving the overall balancing efficiency of the target battery system.

[0123] In several embodiments provided in the present application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely schematic. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the devices, methods and computer program products according to multiple embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the module, a program segment or a part of a code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0124] In addition, the functional modules in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

[0125] If the function is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes. It should be noted that in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variation thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus. In the absence of more restrictions, the elements defined by the sentence "includes..." do not exclude the presence of other identical elements in the process, method, article or apparatus that includes the elements. The above description is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0126] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A battery system active SOC balancing method, characterized in that: include: Determine whether the target battery system has a SOC balancing requirement according to the maximum SOC value, the minimum SOC value and the SOC average value in the target battery system; If it is determined that the target battery system has an SOC balancing requirement, determining the balancing level of each battery cell according to the maximum SOC value or the minimum SOC value and the SOC value of each battery cell in the target battery system; The battery cells in each of the balancing levels are charged or discharged respectively according to the level priority order, so that the SOC values ​​of the battery cells in the target battery system are balanced.

2. The method according to claim 1, characterized in that: The determining whether the target battery system has a SOC balancing requirement according to the maximum SOC value, the minimum SOC value, and the SOC mean value in the target battery system includes: Calculating an SOC mean value of the target battery system according to the SOC value of each battery cell in the target battery system; Determine that the absolute value of the difference between the maximum SOC value and the SOC mean value is a first difference; Determine that the absolute value of the difference between the minimum SOC value and the SOC mean value is a second difference; According to the relationship between the first difference and the second difference and the difference threshold respectively, it is determined whether the target battery system has an SOC balancing requirement.

3. The method according to claim 1 or 2, characterized in that: The SOC balancing requirements include: discharge balancing; If it is determined that the target battery system has an SOC balancing requirement, determining the balancing level of each battery cell according to the minimum SOC value and the SOC value of each battery cell in the target battery system includes: Calculating the discharge difference between the SOC value of each battery cell in the target battery system and the minimum SOC value respectively; The balancing level to which each of the battery cells belongs is determined according to the relationship between the discharge difference of each of the battery cells and the discharge difference threshold; wherein the discharge difference threshold includes one or more thresholds.

4. The method according to claim 3, characterized in that: in, The discharge difference threshold includes: a first discharge difference threshold, a second discharge difference threshold and a third discharge difference threshold; the first discharge difference threshold is greater than the second discharge difference threshold and greater than the third discharge difference threshold; The determining, according to the relationship between the discharge difference of each battery cell and the discharge difference threshold, the balancing level to which each battery cell belongs includes: Determining that the battery cells whose discharge difference is greater than the first discharge difference threshold belong to a first discharge balancing level; Determine that the battery cells whose discharge difference is less than or equal to the first discharge difference threshold and whose discharge difference is greater than the second discharge difference threshold belong to the second discharge balancing level; Determine that the battery cells whose discharge difference is less than or equal to the second discharge difference threshold and greater than the third discharge difference threshold belong to a third discharge balancing level; The discharge priority of the first discharge balance level is greater than that of the second discharge balance level, and the discharge priority of the second discharge balance level is greater than that of the third discharge balance level.

5. The method according to claim 1 or 2, characterized in that: in, The SOC balancing requirements include: charging balancing; If it is determined that the target battery system has an SOC balancing requirement, determining the balancing level of each battery cell according to the maximum SOC value and the SOC value of each battery cell in the target battery system includes: Calculating respectively the charging difference between the SOC value of each battery cell in the target battery system and the maximum SOC value; According to the relationship between the charging difference of each battery cell and the charging difference threshold, the balancing level to which each battery cell belongs is determined; wherein the charging difference threshold is one or more.

6. The method according to claim 5, characterized in that in, The charging difference threshold includes: a first charging difference threshold, a second charging difference threshold and a third charging difference threshold; the first charging difference threshold is greater than the second charging difference threshold and greater than the third charging difference threshold; The determining, according to the relationship between the charging difference of each battery cell and the charging difference threshold, the balancing level to which each battery cell belongs includes: Determining that the battery cells whose charging difference is greater than the first charging difference threshold belong to a first charging equalization level; Determine that the battery cells whose charging difference is less than or equal to the first charging difference threshold and whose charging difference is greater than the second charging difference threshold belong to the second charging equalization level; Determine that the battery cells whose charging difference is less than or equal to the second charging difference threshold and greater than the third charging difference threshold belong to a third charging equalization level; The charging priority of the first charging equalization level is greater than that of the second charging equalization level, and the charging priority of the second charging equalization level is greater than that of the third charging equalization level.

7. The method according to claim 1, characterized in that The charging or discharging of the cells in each of the equalization levels respectively according to the level priority order includes: For each of the balancing levels, determining a charging difference between the SOC value of each battery cell in the balancing level and the maximum SOC value, or a discharging difference between the SOC value of each battery cell in the balancing level and the minimum SOC value; The cells in the balancing level are charged or discharged in order from large to small according to the charging difference or the discharging difference.

8. A battery system, characterized in that: include: Battery cell modules, switch arrays, DCDC modules, control modules and battery management systems; Each battery cell in each battery cell module is connected to the DCDC module through a switch in the corresponding switch array, and the DCDC module is also connected to an external power system and an external power source; the DCDC module is configured to transmit the electric energy of the battery cell with discharge demand to the external power system for use by the external power system, or to transmit the electric energy of the external power source to the battery cell with charging demand for charging of the battery cell with charging demand; The control module is connected to the DCDC module, the switches in the switch array and the battery management system, and the control module is configured to obtain electrical parameters of each battery cell in the battery cell module and send the electrical parameters to the battery management system; Wherein, the battery management system is configured to execute the battery system active SOC balancing method described in any one of claims 1-7 to obtain the charge and discharge control instructions of each battery cell in the battery cell module, and send the same to the control module; the control module controls each switch in the switch array to open or close according to the charge and discharge control instructions, and controls the DCDC module to perform SOC balancing.

9. The battery system according to claim 8, characterized in that: The switch array includes a first switch group and a second switch group; One end of each switch in the first switch group is connected to each battery cell in the battery cell module; The second switch group connects the DCDC module and the other end of each switch in the first switch group.

10. The battery system according to claim 9, characterized in that: The second switch group includes a first switch, a second switch, a third switch and a fourth switch; the switches in the first switch group are numbered according to a setting sequence, namely odd-numbered switches and even-numbered switches; One end of the first switch is connected to one end of the second switch, and the other end of the first switch is connected to one end of the fourth switch; One end of the third switch is connected to the other end of the second switch, and the other end of the third switch is connected to the other end of the fourth switch; Ends of the odd-numbered switches away from the battery cells are connected in parallel to each other and to the first connecting line in the second switch group; Ends of the even-numbered switches away from the battery cells are connected in parallel to each other and to the third connecting line in the second switch group; The second connection line in the second switch group is connected to the first power interface of the DCDC module, and the fourth connection line in the second switch group is connected to the second power interface of the DCDC module; The first connection line and the third connection line are relative connection lines, the second connection line and the fourth connection line are relative connection lines, and the second connection line and the fourth connection line are adjacent connection lines to the first connection line and the third connection line.

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