Balancing method, device and equipment for battery cell

Abstract

The application discloses a balancing method, device and equipment of an electric core, wherein the method comprises the following steps: determining whether a battery pack satisfies a first condition of opening a balancing switch based on a current value of the battery pack and a sleep duration of the battery pack; determining whether each electric core in the battery pack satisfies a second condition of opening the balancing switch based on a voltage value of each electric core and a temperature value of the battery pack; in the case that the battery pack satisfies the first condition, taking an electric core satisfying the second condition as a candidate to be balanced, determining a first balancing duration of each to-be-balanced electric core based on a state of charge value of each to-be-balanced electric core and a balancing current value of the battery pack; determining a balancing duration of each to-be-balanced electric core as a smaller duration between the first balancing duration of each to-be-balanced electric core and a preset balancing duration; and setting a balancing switch of each to-be-balanced electric core to an open state according to the balancing duration of each to-be-balanced electric core.

Description

Technical Field

[0001] This application relates to the field of power battery technology, and relates to, but is not limited to, a method, apparatus, or device for balancing battery cells. Background Technology

[0002] The consistency of power battery cells is related to the lifespan and safety of the battery system. Using cells with significant inconsistencies can lead to obvious voltage fluctuations and decreased power performance. Furthermore, the inconsistencies between cells can be exacerbated, and may even cause battery explosions or fires. Therefore, effective equalization management of power batteries allows for immediate equalization when differences between cells are detected, thereby reducing the impact of inconsistencies on the battery and preventing a vicious cycle. Summary of the Invention

[0003] In view of this, embodiments of this application provide at least one method, apparatus, or device for balancing battery cells.

[0004] The technical solution of this application embodiment is implemented as follows:

[0005] On one hand, embodiments of this application provide a cell balancing method, the method comprising: determining whether the battery pack meets a first condition for balancing switch activation based on the current value of the battery pack and the sleep duration of the battery pack; determining whether a corresponding cell meets a second condition for balancing switch activation based on the voltage value of each cell in the battery pack and the temperature value of the battery pack; if the battery pack meets the first condition, selecting cells that meet the second condition as candidate cells to be balanced, determining a first balancing duration for the corresponding cell based on the state of charge value of each cell to be balanced and the balancing current value of the battery pack; determining the smaller of the first balancing duration and a preset balancing duration for each cell to be balanced as the balancing duration for the corresponding cell to be balanced; and setting the balancing switch of the corresponding cell to be balanced to the on state according to the balancing duration of the cell to be balanced.

[0006] On the other hand, embodiments of this application provide a cell balancing device, the device comprising: a first determining module, configured to determine whether the battery pack meets a first condition for balancing switch activation based on the current value of the battery pack and the sleep duration of the battery pack; a second determining module, configured to determine whether a corresponding cell meets a second condition for balancing switch activation based on the voltage value of each cell in the battery pack and the temperature value of the battery pack; a third determining module, configured to, when the battery pack meets the first condition, select cells that meet the second condition as candidate cells to be balanced, and determine a first balancing duration for the corresponding cell based on the state of charge value of each cell to be balanced and the balancing current value of the battery pack; a fourth determining module, configured to determine the smaller of the first balancing duration of each cell to be balanced and a preset balancing duration as the balancing duration of the corresponding cell to be balanced; and a setting module, configured to set the balancing switch of the corresponding cell to be balanced to an on state according to the balancing duration of the cell to be balanced.

[0007] In another aspect, embodiments of this application provide a computer device, including a memory and a processor, wherein the memory stores a computer program that can run on the processor, and the processor executes the program to implement some or all of the steps in the above-described method.

[0008] In another aspect, embodiments of this application provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements some or all of the steps in the above-described method.

[0009] The cell balancing method provided in this application firstly determines the cells to be balanced based on the current value and the dormancy duration of the battery pack, assuming the battery pack meets the conditions for balancing switch activation. Then, based on the voltage value of each cell in the battery pack and the temperature value of the battery pack, a first balancing duration is determined for each cell to be balanced. Finally, the cells to be balanced are balanced based on this first balancing duration. This ensures the consistency of cell voltage, reduces the impact of inconsistency on the battery, and thus guarantees the performance and lifespan of the battery system.

[0010] It should be understood that the above general description and the following detailed description are merely exemplary and explanatory, and are not intended to limit the technical solutions of this disclosure. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0012] Figure 1A A schematic diagram illustrating the implementation process of a cell balancing method provided in this application embodiment;

[0013] Figure 1B A schematic diagram illustrating the implementation process of a method for determining abnormal cell balancing states provided in this application embodiment;

[0014] Figure 2 Examples of embodiments in this application Figure 1A Implementation flow diagram of step S200 Figure 2 ;

[0015] Figure 3A Examples of embodiments in this application Figure 1A A schematic diagram of the implementation process of step S300;

[0016] Figure 3B Examples of embodiments in this application Figure 3A A schematic diagram of the implementation process of step S310;

[0017] Figure 4 A schematic diagram illustrating the implementation process of a parameter validity verification method provided in this application embodiment;

[0018] Figure 5 The overall technical solution of a cell balancing method provided in the embodiments of this application;

[0019] Figure 6 A schematic diagram of an input module provided in an embodiment of this application;

[0020] Figure 7A A schematic diagram illustrating the implementation process of a data verification logic strategy provided in an embodiment of this application;

[0021] Figure 7B A schematic diagram illustrating the implementation process of a current parameter verification principle for a battery pack, provided in an embodiment of this application;

[0022] Figure 7C A schematic diagram illustrating the implementation process of a cell-based equalization switching logic strategy provided in this application embodiment;

[0023] Figure 7D A schematic diagram illustrating the implementation process of a battery pack-based equalization switching logic strategy provided in this application embodiment;

[0024] Figure 7E A schematic diagram illustrating the implementation process of a logic strategy for calculating the SOC difference of a battery cell, provided in an embodiment of this application;

[0025] Figure 7F A schematic diagram illustrating the implementation process of a fixed equalization time and cell capacity difference provided in an embodiment of this application;

[0026] Figure 7G A schematic diagram illustrating the implementation process of a time-balancing calculation logic strategy provided in this application embodiment;

[0027] Figure 7H A schematic diagram illustrating the implementation process of a balanced stopping logic strategy provided in an embodiment of this application;

[0028] Figure 8 A schematic diagram of an output module provided in an embodiment of this application;

[0029] Figure 9 A schematic diagram of the composition structure of a battery cell equalization device provided in an embodiment of this application;

[0030] Figure 10 This is a schematic diagram of the hardware entity of a computer device provided in an embodiment of this application. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application are further described in detail below with reference to the accompanying drawings and embodiments. The described embodiments should not be regarded as limitations on this application. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0033] It should be noted that the terms "first, second, and third" used in the embodiments of this application are merely to distinguish similar objects and do not represent a specific ordering of objects. It is understood that "first, second, and third" can be interchanged in a specific order or sequence where permitted, so that the embodiments of this application described herein can be implemented in an order other than that illustrated or described herein.

[0034] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of this application pertain. It should also be understood that terms such as those defined in general dictionaries should be understood to have a meaning consistent with their meaning in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0035] State of Charge (SOC) is the ratio of a battery's remaining capacity after a period of use or long-term storage to its capacity when fully charged, usually expressed as a percentage. Its value ranges from 0 to 1; SOC = 0 indicates the battery is fully discharged, and SOC = 1 indicates the battery is fully charged.

[0036] Printed Circuit Board (PCB) is an important electronic component that serves as the support for electronic components. Its main function is to connect various electronic components through circuits, enabling conduction and transmission. It is a key electronic interconnect component in electronic products.

[0037] Analog Front End (AFE) chip is a chip used for signal acquisition and processing. Its function is to convert physical quantities (such as temperature, pressure, sound, etc.) into electrical signals, and to amplify, filter, sample, quantize, and perform other processing on the electrical signals so that subsequent digital signal processors or microprocessors can digitize the signals.

[0038] Cell consistency: The phenomenon that battery parameters such as capacity, SOC, internal resistance, and voltage differ due to internal differences or different external usage conditions.

[0039] Application Programming Interface (API) consists of predefined functions.

[0040] The consistency of battery cells is crucial to the lifespan and safety of the battery system. Using cells with significant inconsistencies can lead to substantial voltage fluctuations and decreased power performance. If these differences worsen, they can even cause battery explosions or fires. Therefore, effective cell balancing management allows for immediate balancing upon detection of cell discrepancies, minimizing their impact and preventing a vicious cycle. Cell balancing is a critical control function of the power battery system, aiming to bring the voltage of all individual cells to a common level.

[0041] This application provides a cell balancing method, such as... Figure 1A As shown, the method may include steps S100 to S500:

[0042] Step S100: Based on the current value of the battery pack and the sleep duration of the battery pack, determine whether the battery pack meets the first condition for the equalization switch to be turned on;

[0043] Here, the battery pack's current value and sleep duration are collected by the Battery Management System (BMS). The BMS is a device that monitors the status of energy storage batteries, primarily for intelligent management and maintenance of each battery cell, preventing overcharging and over-discharging, extending battery life, and monitoring battery status. The sleep duration refers to the period during which the battery pack is not in operation. In some embodiments, the first condition may include a first sub-condition or a second sub-condition.

[0044] In some embodiments, step S100 may include steps S110 to S130:

[0045] Step S110: Determine whether the sleep duration of the battery pack is within a first preset duration. If the sleep duration of the battery pack is within the first preset duration, determine that the battery pack meets the first sub-condition for the equalization switch to be turned on.

[0046] Step S120: Determine whether the current value of the battery pack is within a preset current range within a second preset time period. If the current value of the battery pack is within the preset current range within a second preset time period, determine that the battery pack meets the second sub-condition for the equalization switch to be turned on.

[0047] Step S130: If the battery pack satisfies the first sub-condition or the second sub-condition, determine that the battery pack satisfies the first condition for the equalization switch to be turned on.

[0048] Step S200: Based on the voltage value of each cell in the battery pack and the temperature value of the battery pack, determine whether the corresponding cell meets the second condition for the equalization switch to be turned on;

[0049] Here, different second conditions for activating the equalization switch can be designed based on different cell systems. In some embodiments, the cell system may include ternary (NCM, Nickel Cobalt Manganese) cells and lithium iron phosphate (LPF, Lithium Iron Phosphate) cells. The LPF cell is composed of lithium iron phosphate (LiFePO4) material with an olivine structure coated on aluminum foil as the positive electrode and graphite material coated on copper foil as the negative electrode. The LPF cell has good safety and is currently the most commonly used cell system for new energy vehicles and energy storage power stations. The NCM cell's positive electrode material is composed of nickel, cobalt, and manganese in a certain proportion. The NCM cell has high energy density, long lifespan, and high discharge rate, and is widely used in mobile power supplies, electric vehicles, drones, and other fields.

[0050] Step S300: If the battery pack meets the first condition, the cells that meet the second condition are selected as candidate cells to be balanced. Based on the state of charge value of each cell to be balanced and the balancing current value of the battery pack, the first balancing time of the corresponding cell to be balanced is determined.

[0051] Here, balancing current refers to injecting or extracting a certain current into or from certain cells in the battery pack through the BMS system to achieve charge balance among the cells. The specific balancing current is calculated and controlled by the BMS system based on the actual situation of the battery pack. Generally speaking, the goal of balancing current is to keep the charge and discharge states of the battery cells consistent within a certain range, thus avoiding problems such as performance degradation or shortened lifespan of the entire battery pack due to excessive differences between cells.

[0052] The SOC value is determined by the relationship table between the state of charge and open circuit voltage (SOC-OCV) of the battery pack, wherein the SOC-OCV relationship table is obtained through cell experiments.

[0053] Step S400: Determine the smaller of the first balancing time and the preset balancing time for each battery cell to be balanced as the balancing time for the corresponding battery cell to be balanced.

[0054] Here, the preset balancing duration is set by the balancing capability of the AFE chip. In some embodiments, the preset balancing duration can be 8 hours.

[0055] Step S500: According to the balancing time of the cell to be balanced, set the balancing switch of the corresponding cell to be balanced to the on state.

[0056] During the cell balancing process, certain abnormal situations require the corresponding module to stop balancing, such as... Figure 1BAs shown, the method includes steps S510 and S520: Step S510: When the current parameter value of the battery pack meets the first preset range, turn off the balancing switch of the battery cell in the balancing state in the battery pack; Step S520: When the current parameter value of each battery cell in the balancing state meets the second preset range, turn off the balancing switch of the corresponding battery cell in the balancing state.

[0057] The balancing method provided in this application firstly determines that the battery pack meets the conditions for balancing switch activation based on the current value and the dormancy duration of the battery pack. Then, based on the voltage value of each cell in the battery pack and the temperature value of the battery pack, it identifies the cells to be balanced. Next, based on the state of charge value of each cell to be balanced and the balancing current value of the battery pack, it determines a first balancing duration for the corresponding cell. Finally, it balances the cells to be balanced based on this first balancing duration. This ensures the consistency of cell voltage, reduces the impact of inconsistency on the battery, and thus guarantees the performance and lifespan of the battery system.

[0058] In some embodiments, when the cell system type is NCM cell, step S200 above may include a third sub-condition or a fourth sub-condition, and may include steps S210 to S250:

[0059] Step S210: If the system type of the battery cell is determined to be ternary battery cell, determine the maximum voltage value and the minimum voltage value based on the voltage values ​​of all cells in the battery pack;

[0060] Step S220: Determine the difference between the voltage value of each cell in the battery pack and the minimum voltage value as the cell voltage difference of the corresponding cell;

[0061] Step S230: Determine whether the maximum voltage value is within a preset voltage range and whether the cell voltage difference of each cell is within a first preset cell voltage difference range; if the maximum voltage value is within a preset voltage range and the cell voltage difference of each cell is within a first preset cell voltage difference range, determine that the corresponding cell meets the third sub-condition for the equalization switch to be turned on.

[0062] Step S240: Determine whether the maximum voltage value is not within the preset voltage range and whether the cell voltage difference of each cell is within the second preset cell voltage difference range; if the maximum voltage value is not within the preset voltage range and the cell voltage difference of each cell is within the second preset cell voltage difference range, determine that the corresponding cell meets the fourth sub-condition for the equalization switch to be turned on.

[0063] Step S250: If each of the battery cells satisfies the third sub-condition or the fourth sub-condition, determine that the corresponding battery cell satisfies the second condition for the equalization switch to be turned on.

[0064] In some embodiments, step S200 above, when the cell system type is an LPF cell, such as Figure 2 As shown, steps S211 to S241 may be included:

[0065] Step S211: Determine whether the state of charge value of each cell in the battery pack is within a first preset state of charge range, and whether the temperature value is within a preset temperature range.

[0066] Step S221: If the state of charge value of each cell in the battery pack is within a first preset state of charge range and the temperature value is within a preset temperature range, determine that the corresponding cell meets the second condition for the equalization switch to be turned on.

[0067] Step S231: Alternatively, determine whether the state of charge value of each cell in the battery pack is within a second preset state of charge range, and whether the temperature value is within a preset temperature range.

[0068] Step S241: If the state of charge value of each cell in the battery pack is within a second preset state of charge range and the temperature value is within a preset temperature range, then the corresponding cell is determined to meet the second condition for the equalization switch to be turned on.

[0069] Wherein, the first preset charge range is greater than or equal to 95, and the second preset charge range is less than or equal to 20.

[0070] In some embodiments, step S300 above, such as Figure 3A As shown, steps S310 to S330 may be included:

[0071] Step S310: Based on the state of charge value of each cell to be balanced and the factory-calibrated value of the cell capacity of the corresponding cell to be balanced, determine the initial capacity difference of the corresponding cell to be balanced.

[0072] Step S320: Based on the initial capacity difference of each cell to be balanced and the balancing current value of the battery pack, determine the second balancing time for the corresponding cell to be balanced;

[0073] Here, the specific calculation method for the second equalization time of the battery cell to be equalized is given in formula (1):

[0074] T = △Q / I (1);

[0075] Where △Q represents the initial capacity difference of the cells to be balanced, I represents the balancing current, and T represents the second balancing time.

[0076] Step S330: Divide the second balancing time of each cell to be balanced by the preset balancing duty cycle and determine the result as the first balancing time of the corresponding cell to be balanced.

[0077] Here, the equalization duty cycle refers to the ratio of the duration of the equalization period to the duration of the unit cycle, where the unit cycle consists of the voltage sampling period and the equalization period. In this embodiment, the duration of the equalization period refers to the second equalization duration. In some embodiments, the equalization duty cycle can be 0.5.

[0078] In some embodiments, step S310 above, such as Figure 3B As shown, steps S311 to S314 may be included:

[0079] Step S311: Based on the voltage value of each of the cells to be balanced and the temperature of the battery pack, determine the state of charge value of the corresponding cell to be balanced.

[0080] Step S312: Determine the minimum state of charge value based on the state of charge values ​​of all cells in the battery pack;

[0081] Step S313: Determine the difference between the state of charge value of each cell to be balanced and the minimum state of charge value as the state of charge difference of the corresponding cell to be balanced.

[0082] Step S314: The product of the state of charge difference of each cell to be balanced and the factory-calibrated capacity of the corresponding cell to be balanced is determined as the initial capacity difference of the corresponding cell to be balanced.

[0083] Before determining that the battery pack meets the first condition for the equalization switch to turn on, such as Figure 4 As shown, it may include steps S410 and S420:

[0084] Step S410: Based on the current parameter data values ​​of the battery pack and the preset parameter threshold, determine the relationship between the current parameter data values ​​of the battery pack and the preset parameter threshold;

[0085] Here, if the current parameter data value of the battery pack is within the preset parameter threshold, the parameter data value is determined to be reasonable; if the current parameter data value of the battery pack is not within the preset parameter threshold, the parameter data value is determined to be unreasonable. The selection of the preset parameter threshold needs to be determined according to the power of the battery pack and the model of the battery cells in the battery pack.

[0086] Step S420: If the parameter data value is determined to be within the range of a preset parameter threshold, the validity of the parameter data value is determined based on the parameter data value and the validity flag bit of the parameter.

[0087] Here, the flag bit is obtained by the BMS system after collecting relevant parameter information and filtering to determine whether the signal threshold is reasonable. If the signal threshold of the parameter is determined to be reasonable, the flag bit is 1, which is a valid flag bit; if the signal threshold of the parameter is determined to be unreasonable, the flag bit is 0, which is an invalid flag bit.

[0088] The balancing method for the battery cell described above will be specifically described below with reference to a specific embodiment. This embodiment is described from three parts according to the data flow: the input module, the logic module, and the output module. However, it is worth noting that this specific embodiment is only for better illustration of this application and does not constitute an improper limitation of this application.

[0089] This application provides an overall technical solution for a cell balancing method, such as... Figure 5 As shown, the method may include steps S600 to S800:

[0090] Step S600: Input variables and process them;

[0091] To achieve cell balancing, the necessary parameter variables must first be input. In some embodiments, the input parameter variables can be the voltage (0-5V) and RMS value of all cells in the battery pack, the maximum single cell voltage (0-5V), the minimum single cell voltage (0-5V), the battery pack temperature and RMS value, the PCB board temperature and RMS value, the SOC and RMS value of all cells, the battery pack current and RMS value, the minimum SOC and RMS value of the cells, the sleep time, the balancing switch and its status, etc. Table 1 below lists some of the input parameters, their corresponding parameter types and explanations:

[0092] Table 1 Input Parameter Description

[0093]

[0094]

[0095] Due to the limited memory efficiency of the microcontroller, the input module receives integer data. To facilitate data processing and logical operations on these input parameters by the logic module, the data type of the input parameters needs to be converted to floating-point type, such as... Figure 6 As shown, the method may include steps S610 and S620:

[0096] Step S610: Input the parameter data collected by the hardware through the API input interface. The parameters involved include: cell voltage, maximum single cell voltage, minimum single cell voltage, cell voltage flag, battery pack temperature, PCB board temperature, battery pack temperature flag, PCB board temperature flag, circuit balancing status, minimum single cell SOC value, SOC flag, cell balancing switch flag, total balancing switch flag, BMS sleep time, battery status, battery pack current, battery pack current flag, and single cell SOC.

[0097] Step S620: Convert the input parameter data to single type and obtain the floating-point data of each parameter.

[0098] Step S700: Logic strategy and method;

[0099] In this embodiment, the first step of the charge balancing strategy is to verify the rationality of the hardware-collected parameter data. This is because, during the balancing process, the cell current discharges through the hardware (AFE chip) to ensure consistent voltage across all cells, while simultaneously raising the PCB board temperature. Unreasonably and frequently opening the balancing switch during the balancing process can lead to abnormal PCB board temperature and even serious problems such as battery fires or explosions. Therefore, the first key to cell balancing is verifying the legality of the parameter data; the balancing function can only be activated if the battery and PCB board parameters are reasonable and valid. Figure 7A As shown, the validity verification of input parameters may include steps S701 to S703:

[0100] Step S701: Verification of the validity of each input parameter, specifically as follows: The battery pack temperature value input at input port 3 and the flag value of the battery pack temperature input at input port 4 are verified by the battery pack temperature validity verification unit, and the verification result is output; the cell voltage value input at input port 1 and the flag value of the cell voltage input at input port 2 are verified by the cell voltage validity verification unit, and the verification result is output; the PCB board temperature value of the battery pack input at input port 5 and the flag value of the PCB board temperature input at input port 6 are verified by the PCB board temperature validity verification unit, and the verification result is output; input terminals The SOC value of the battery cell input at port 7 and the SOC flag value of the battery cell input at port 6 are verified by the battery cell SOC validity verification unit, and the verification result is output. The battery pack current value input at port 9 and the battery pack current flag value input at port 10 are verified by the battery pack current validity verification unit, and the verification result is output. The circuit balance state value input at port 11 is verified by the circuit balance state validity verification unit, and the verification result is output. The total balance switch flag value input at port 12 is verified by the total balance switch flag parameter validity verification unit, and the verification result is output.

[0101] Step S702: Based on the parameter verification results of step S701, obtain the total verification results of all input parameters through the total parameter verification unit;

[0102] Step S703: Based on the overall verification result, proceed to the enable calculation module to determine the enable parameter value. When the enable parameter is 1, it means that the parameter verification has passed and the next module's processing unit can proceed. Otherwise, the parameter verification has failed.

[0103] Furthermore, taking current parameters as an example, the parameter verification principle of step S701 will be explained in detail, such as... Figure 7B As shown, it may include steps S7011 and S7012:

[0104] Step S7011: The current value of the battery pack input at input port 1 is processed by the software calculation module. Based on the effective current limit set by the software calculation module, it is determined whether the input current data is within the limit range.

[0105] Step S7012: The current flag bit of the battery pack input at input port 2 is ANDed with the output of step S7011, and the result of the current validity verification is output. If the input current data is within the limit range and the current flag bit is 1, the current is judged to be valid and 1 is output; otherwise, 0 is output.

[0106] The following are some specific strategies for performing parameter principle verification. Equilibrium will only enable computation when the following conditions are met:

[0107] - Valid for any cell voltage state;

[0108] - Effective at any board temperature;

[0109] -SOC status is valid;

[0110] - The overall temperature range of the package is reasonable (calibrable);

[0111] -Any cell voltage range is reasonable (calibrable);

[0112] -Any circuit board with a reasonable temperature range (calibrable);

[0113] - Any cell has a reasonable (calibrable) SOC range;

[0114] After the parameter validity verification is passed, the next step is to verify whether the input parameters meet the equalization activation conditions. Here, the equalization activation conditions include cell-based equalization activation conditions and battery pack-based equalization activation conditions. There is no order restriction between judging these two conditions. In this embodiment, based on the importance of the battery system parameters, the cell-based equalization conditions are judged first.

[0115] For cell-based balancing conditions, the cell system in the battery pack is first determined. Then, based on the determined system type and the corresponding balancing activation conditions, it is judged whether the cells in the battery pack meet the balancing activation conditions. In this embodiment, the cell system may include NCM cells and LFP cells, and the corresponding strategies are as follows:

[0116] NCM cell: The maximum cell voltage of the battery system is greater than 4V and the cell voltage difference is greater than 35mV, or the maximum cell voltage is less than or equal to 4V and the cell voltage difference is greater than 25mV.

[0117] LFP cells: The battery system temperature is greater than or equal to 0°C, and the cell's SOC value is in the non-plateau region, i.e., SOC value less than or equal to 20 or SOC value greater than or equal to 95. In this embodiment, due to computer resource limitations, when judging SOC, the maximum and minimum SOC values ​​are first obtained, and then the judgment is made by comparing the maximum and minimum SOC values ​​with a preset SOC threshold. This design not only consumes less computer resources but also improves the program's running efficiency. Specific strategies are as follows... Figure 7C As shown, steps S710 to S719 may be included:

[0118] Step S710: Input the battery pack temperature from port 4, determine whether its value is greater than or equal to 0℃, and obtain the determination result;

[0119] Step S711: The SOC values ​​of all cells input through input port 5 are calculated using the maximum and minimum values ​​respectively to obtain the maximum and minimum SOC values. Then, it is determined whether the obtained maximum value is greater than or equal to 95 and the minimum value is less than or equal to 20, and the obtained results are ORed.

[0120] Step S712: Perform an AND operation based on the results of steps S710 and S711 to determine the result of the equalization start-up condition of the LFP cell system being met, and output the equalization strategy judgment result of the LFP cell system.

[0121] Step S713: The cell voltage input at input port 1 and the minimum cell voltage input at input port 3 enter the voltage difference processing unit, and output the cell voltage difference value between each cell voltage and the minimum cell voltage;

[0122] Step S714: Based on the result obtained in step S713, the cell voltage difference value judgment unit is entered, the calculated cell voltage difference is compared with the preset cell voltage difference of 25mV, and the comparison result is obtained.

[0123] Step S715: The maximum cell voltage input at input port 2 is compared with the preset voltage threshold of 4V, and the comparison result is obtained. If the maximum cell voltage is less than or equal to 4V, the result obtained in step S714 is ANDed with the result obtained in step S714, and the AND operation result is obtained.

[0124] Step S716: Based on the result obtained in step S713, the cell voltage difference value judgment unit is entered, the calculated cell voltage difference is compared with the preset cell voltage difference of 35mV, and the comparison result is obtained.

[0125] Step S717: The maximum cell voltage input at input port 2 is compared with the preset voltage threshold of 4V, and the comparison result is obtained. If the maximum cell voltage is greater than 4V, the result obtained in step S716 is ANDed with the result obtained in step S716, and the AND operation result is obtained.

[0126] Step S718: Perform an OR operation on the results obtained in step S715 and step S717 to determine the result that the equalization start-up condition of the NCM cell system is satisfied, and output the equalization strategy judgment result of the NCM cell system.

[0127] Step S719: When the cell system is determined to be LFP, perform LFP cell system strategy judgment and output the judgment result; when the cell system is determined to be NCM, perform NCM cell system strategy judgment and output the judgment result. For example, when LFPCellBal = 1, it can be represented as an LFP cell system; when LFPCellBal = 0, it can be represented as an NCM cell system.

[0128] After determining whether the balancing activation conditions are met based on the battery cell, it is also necessary to determine whether the balancing activation conditions are met based on the battery pack. In this embodiment, the strategy can be: the balancing switch is only allowed to be turned on when the battery management system sleep time is greater than or equal to 1 hour (calibrable) or the battery system current is less than or equal to 3A (calibrable) for 1 hour (calibrable). Figure 7D As shown, steps S721 to S725 may be included:

[0129] Step S721: Compare the battery pack sleep time input at input port 1 with the preset sleep time of 1 hour to determine whether the battery pack sleep time is greater than or equal to 1 hour;

[0130] Step S722: The battery pack current input from input port 2 is judged by the current condition judgment unit against the preset conditions, and the judgment result is obtained. Specifically, it is judged whether the battery pack current value is less than or equal to 3A, and the current value within this range is maintained for at least 1 hour.

[0131] Step S723: Perform an OR operation based on the results obtained in steps S721 and S722 to determine whether the equalization activation conditions of the battery pack are met.

[0132] Step S724: The enable operation result input from input port 3 is inverted. It should be clear that the design of this logic unit is to handle some abnormal enable results during the operation of the strategy.

[0133] Step S725: Based on the results obtained in steps S723 and S724, perform an AND operation to determine whether the equalization activation conditions based on the battery pack are met, and output the judgment result of the equalization strategy based on the battery pack.

[0134] Based on the determination that the equalization start-up conditions based on individual cells and the equalization start-up conditions based on the battery pack are met, the SOC difference of the cells to be equalized is calculated. The SOC difference is one of the key indicators for equalization start-up. It can be obtained by using the voltage value of the cell to be equalized and the temperature value of the battery pack, and through the SOC-OCV relationship table, to further determine the SOC difference of each cell to be equalized. The calculation principle of the SOC difference is as follows... Figure 7E As shown, steps S731 to S733 may be included:

[0135] Step S731: The temperature value of the battery pack input from input port 1 is used to obtain the discretized temperature value based on the set discretization rules;

[0136] Step S732: Based on the voltage of all cells input at input port 2, and the discretized temperature value obtained in step S731, determine the SOC value of each cell through the SOC-OCV relationship table;

[0137] Step S733: Calculate the minimum SOC value based on the obtained SOC values ​​of all cells, obtain the minimum SOC value, subtract the obtained minimum SOC value from the SOC value of each cell to be balanced, obtain the SOC difference of each cell to be balanced, and output it.

[0138] After determining the SOC difference of each cell to be balanced, the obtained SOC difference of each cell is multiplied by the factory rated capacity of the corresponding cell to determine the initial capacity difference of each cell. Simultaneously, based on the balancing capability of the AFE chip, a fixed balancing time is set, such as... Figure 7F As shown, steps S741 to S743 may be included:

[0139] Step S741: The battery pack strategy determination result input from input port 1 is processed by the time processing module, and a fixed balancing time of 8 hours is set according to the balancing capability of the AFE chip.

[0140] Step S742: The SOC values ​​of each cell to be balanced input at input port 4 are processed by the minimum value calculation and difference calculation module, and compared with the factory calibration capacity of the corresponding cell input at input port 2 and the SOC difference of each cell to be balanced input at input port 3. The initial capacity difference of each cell to be balanced is obtained by the initial capacity calculation module.

[0141] Step S743: Multiply the battery pack strategy determination result input from input port 1 with the initial capacity difference of each cell to be balanced obtained in step S742, and output the final result; it should be noted that when the battery pack strategy determination result = 1, the result output in this step is a valid result, otherwise the corresponding result is 0.

[0142] After obtaining the initial cell capacity difference of all cells to be balanced, the actual balancing time of the corresponding cell can be obtained through formula (1). At the same time, the balancing duty cycle is considered. In this embodiment, the balancing start time and voltage acquisition time each account for half. Finally, the balancing time calculated is compared with the fixed balancing time of 8 hours (which can be calibrated), and the smaller one is set as the balancing time of the corresponding cell. The balancing time calculation logic strategy is as follows: Figure 7G It needs to be made clear that, Figure 7G The area outside the marked box is Figure 7D and Figure 7F The implementation diagram of the corresponding principle is not described here. Only the principle shown in the block diagram in 7G is explained, which may include steps S751 to S755:

[0143] Step S751: After the cell balancing status value input from input port 2 is converted to a different type, it is compared with the period time and the balancing duty cycle of 0.5 to determine the voltage acquisition time corresponding to the period sampling time.

[0144] Step S752: The voltage value of the cell to be balanced and the corresponding resistance of the cell to be balanced are input through the equalization current acquisition unit to obtain the equalization current of the cell to be balanced.

[0145] Step S753: Based on the time determined in step S751 and the equalization current of the cells to be equalized determined in step S752, determine the capacity difference of each cell to be equalized within the corresponding time period using formula (1).

[0146] Step S754: Based on the previous Figure 7F The initial capacity difference of each cell to be balanced obtained in step S753 is added to the capacity of the corresponding cell obtained in step S753, and the balancing time is determined based on the balancing current of the corresponding cell obtained in step S752.

[0147] Step S755: Based on the balancing time obtained in step S754, compare it with the set fixed balancing time, determine the smaller value as the balancing time of the corresponding cell to be balanced, and output it.

[0148] When the battery cells are in an equalization state, the equalization process should be stopped if the voltage consistency of the corresponding battery cells meets certain conditions or if an abnormal situation occurs. Figure 7H The diagram illustrates the implementation principle of equalization stopping, which may include steps S761 to S764:

[0149] Step S761: The minimum cell SOC value of the balanced state input at input port 2 is compared with a preset threshold, and the comparison result is output.

[0150] Step S762: The battery status input at input port 3 is compared with the battery status verification unit, and the verification result is output.

[0151] Step S763: Compare the maximum PCB temperature input at input port 4 with the preset temperature threshold and output the corresponding result;

[0152] Step S764: Based on the above steps S761 to S763, and the equalization time of the corresponding equalization state of the cell input at input port 1, enter the equalization stop logic strategy operation unit and output the equalization command switch of the corresponding cell.

[0153] The following outlines the general strategies for stopping recovery in balanced mode. Specific strategies need to be designed based on the vehicle's overall logic:

[0154] When the SOC of the battery cell is less than 5% (calibrable), stop balancing;

[0155] When the battery cell SOC is greater than 25% (calibrable), rebalancing is restored.

[0156] If the PCB board temperature exceeds 90℃ (calibrable), turn off the equalization function.

[0157] When the PCB board temperature is below 65℃ (calibrable), enable equalization.

[0158] Step S800: Output variables and processing.

[0159] If other modules in the battery system need to use the parameter information obtained in step S700 for further processing, the output module can send the corresponding parameter data to other modules through the output API interface. Here, we will use three parameters—balancing status, balancing switch command, and balancing time—for example... Figure 8 As shown, it may include steps S810 and S820:

[0160] Step S810: Input port 3 inputs the cell's equalization status value, input port 2 inputs the cell's equalization time value, and input port 1 inputs the cell's equalization switch command value;

[0161] Step S820: Based on the parameter values ​​obtained in step S810, output them through a unified API output interface. The next module can obtain the corresponding parameter values ​​by connecting to the API output interface.

[0162] Regarding the above implementation process, this application describes a system development method for ensuring the consistency of battery system cells. This cell balancing method can immediately activate the balancing switch of the corresponding cell when it is determined that the cell needs balancing, thereby ensuring the consistency of cell voltage, reducing the impact of inconsistency on the battery, and guaranteeing the performance and lifespan of the battery system. This cell balancing method is clear, reliable, and meets the functional safety requirements of automobiles.

[0163] Based on the foregoing embodiments, this application provides a battery cell equalization device, which includes various modules and units included in each module, and can be implemented by a processor in a computer device; of course, it can also be implemented by specific logic circuits; in the implementation process, the processor can be a central processing unit (CPU), a microprocessor unit (MPU), a digital signal processor (DSP), or a field programmable gate array (FPGA), etc.

[0164] This application provides a cell equalization device, such as... Figure 9 As shown, the device 900 includes:

[0165] The first determining module 901 is used to determine whether the battery pack meets the first condition for the equalization switch to be turned on based on the current value of the battery pack and the sleep duration of the battery pack; the second determining module 902 is used to determine whether the corresponding cell meets the second condition for the equalization switch to be turned on based on the voltage value of each cell in the battery pack and the temperature value of the battery pack; the third determining module 903 is used to, if the battery pack meets the first condition, take the cells that meet the second condition as candidate cells to be equalized, and determine the first equalization duration of the corresponding cells to be equalized based on the state of charge value of each cell to be equalized and the equalization current value of the battery pack; the fourth determining module 904 is used to determine the smaller of the first equalization duration of each cell to be equalized and a preset equalization duration as the equalization duration of the corresponding cell to be equalized; and the setting module 905 is used to set the equalization switch of the corresponding cell to be equalized to the on state according to the equalization duration of the cell to be equalized.

[0166] In some embodiments, the first determining module includes: a first determining unit, configured to determine whether the sleep duration of the battery pack is within a first preset duration; and if the sleep duration of the battery pack is within the first preset duration, determine that the battery pack meets a first sub-condition for the equalization switch to be turned on; a second determining unit, configured to determine whether the current value of the battery pack is within a preset current range within a second preset duration; and if the current value of the battery pack is within the preset current range within the second preset duration, determine that the battery pack meets a second sub-condition for the equalization switch to be turned on; and a first determining unit, configured to determine that the battery pack meets the first condition for the equalization switch to be turned on if the battery pack meets either the first sub-condition or the second sub-condition.

[0167] In some embodiments, the second determining module includes: a second determining unit: configured to determine a maximum voltage value and a minimum voltage value based on the voltage values ​​of all cells in the battery pack when the system category of the battery cell is determined to be a ternary battery cell; a third determining unit: configured to determine the difference between the voltage value and the minimum voltage value of each cell in the battery pack as the cell voltage difference of the corresponding cell; a third judging unit: configured to judge whether the maximum voltage value is within a preset voltage range and whether the cell voltage difference of each cell is within a first preset cell voltage difference range; and a fourth determining unit: configured to determine whether the maximum voltage value is within a preset voltage range and whether the cell voltage difference of each cell is within a first preset cell voltage difference range. Under the condition of a preset cell voltage difference range, determine that the corresponding cell meets the third sub-condition for the equalization switch to be turned on; the fourth judgment unit is used to determine whether the maximum voltage value is not within the preset voltage range and whether the cell voltage difference of each cell is within the second preset cell voltage difference range; the fifth determination unit is used to determine that the corresponding cell meets the fourth sub-condition for the equalization switch to be turned on when the maximum voltage value is not within the preset voltage range and the cell voltage difference of each cell is within the second preset cell voltage difference range; the sixth determination unit is used to determine that the corresponding cell meets the second condition for the equalization switch to be turned on when each of the cells meets the third or fourth sub-condition.

[0168] In some embodiments, the second determining module further includes: a fifth determining unit, configured to determine whether the state of charge (SOC) value of each cell in the battery pack is within a first preset SOC range and whether the temperature value is within a preset temperature range; and if the SOC value of each cell in the battery pack is within the first preset SOC range and the temperature value is within the preset temperature range, determine that the corresponding cell meets the second condition for the equalization switch to be turned on; a sixth determining unit, or configured to determine whether the SOC value of each cell in the battery pack is within a second preset SOC range and whether the temperature value is within a preset temperature range; and if the SOC value of each cell in the battery pack is within the second preset SOC range and the temperature value is within the preset temperature range, determine that the corresponding cell meets the two conditions for the equalization switch to be turned on; wherein the first preset SOC range is greater than or equal to 95, and the second preset SOC range is less than or equal to 20.

[0169] In some embodiments, the third determining module includes: a seventh determining unit, configured to determine the initial capacity difference of the corresponding cell to be balanced based on the state of charge value of each cell to be balanced and the factory-calibrated value of the cell capacity of the corresponding cell to be balanced; an eighth determining unit, configured to determine the second balancing time of the corresponding cell to be balanced based on the initial capacity difference of each cell to be balanced and the balancing current value of the battery pack; and a ninth determining unit, configured to determine the result of dividing the second balancing time of each cell to be balanced by a preset balancing duty cycle as the first balancing time of the corresponding cell to be balanced.

[0170] In some embodiments, the seventh determining unit includes: a first determining subunit, configured to determine the state of charge (SOC) value of the corresponding SOC cell based on the voltage value of each SOC cell and the temperature of the battery pack; a second determining subunit, configured to determine the minimum SOC value based on the SOC values ​​of all cells in the battery pack; a third determining subunit, configured to determine the difference between the SOC value of each SOC cell and the minimum SOC value as the SOC difference of the corresponding SOC cell; and a fourth determining subunit, configured to determine the initial capacity difference of the corresponding SOC cell by multiplying the SOC difference of each SOC cell by the factory-calibrated capacity value of the corresponding SOC cell.

[0171] In some embodiments, the device further includes: a first shut-off module, configured to shut off the balancing switch of a cell in a balanced state in the battery pack when the current parameter value of the battery pack meets a first preset range; and a second shut-off module, configured to shut off the balancing switch of a cell in a corresponding balanced state when the current parameter value of each cell in a balanced state meets a second preset range.

[0172] In some embodiments, the apparatus further includes: a fifth determining module, configured to determine the relationship between the current parameter data value of the battery pack and the preset parameter threshold based on the current parameter data value of the battery pack and the preset parameter threshold; and a sixth determining module, configured to determine the validity of the parameter data value based on the parameter data value and the validity flag bit of the parameter when it is determined that the parameter data value is within the range of the preset parameter threshold.

[0173] The descriptions of the apparatus embodiments above are similar to those of the method embodiments above, and have similar beneficial effects. In some embodiments, the functions or modules included in the apparatus provided in this application can be used to perform the methods described in the method embodiments above. For technical details not disclosed in the apparatus embodiments of this application, please refer to the descriptions of the method embodiments of this application for understanding.

[0174] It should be noted that, in the embodiments of this application, if the above-described methods are implemented as software functional modules and sold or used as independent products, they can also be stored in a computer-readable storage medium. Based on this understanding, the technical solutions of the embodiments of this application, or the parts that contribute to related technologies, can be embodied in the form of a software product. This software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), magnetic disks, or optical disks. Thus, the embodiments of this application are not limited to any specific hardware, software, or firmware, or any combination of hardware, software, and firmware.

[0175] This application provides a computer device including a memory and a processor. The memory stores a computer program that can run on the processor. When the processor executes the program, it implements some or all of the steps in the above-described method.

[0176] This application provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements some or all of the steps in the above-described method. The computer-readable storage medium can be transient or non-transient.

[0177] This application provides a computer program including computer-readable code, wherein when the computer-readable code is executed in a computer device, a processor in the computer device performs some or all of the steps in the above-described method.

[0178] This application provides a computer program product, which includes a non-transitory computer-readable storage medium storing a computer program. When the computer program is read and executed by a computer, it implements some or all of the steps in the above-described method. This computer program product can be implemented specifically through hardware, software, or a combination thereof. In some embodiments, the computer program product is specifically embodied as a computer storage medium; in other embodiments, the computer program product is specifically embodied as a software product, such as a software development kit (SDK), etc.

[0179] It should be noted that the descriptions of the various embodiments above tend to emphasize the differences between them, while their similarities or commonalities can be referred to interchangeably. The descriptions of the above embodiments of the device, storage medium, computer program, and computer program product are similar to the descriptions of the above method embodiments and have similar beneficial effects. For technical details not disclosed in the embodiments of the device, storage medium, computer program, and computer program product of this application, please refer to the descriptions of the method embodiments of this application for understanding.

[0180] This application provides a computer device, such as... Figure 10 As shown, the hardware entities of the computer device 1000 include: a processor 1001, a communication interface 1002, and a memory 1003. The processor 1001 typically controls the overall operation of the computer device 1000. The communication interface 1002 enables the computer device to communicate with other terminals or servers via a network. The memory 1003 is configured to store instructions and applications executable by the processor 1001, and can also cache data to be processed or already processed (e.g., image data, audio data, voice communication data, and video communication data) in the processor 1001 and various modules of the computer device 1000. It can be implemented using flash memory (FLASH) or random access memory (RAM). Data transfer between the processor 1001, the communication interface 1002, and the memory 1003 can be performed via a bus 1004.

[0181] It should be understood that the phrase "one embodiment" or "an embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of this application. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. It should be understood that in the various embodiments of this application, the sequence numbers of the above steps / processes do not imply a sequential order of execution; the execution order of each step / process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application. The sequence numbers of the above embodiments of this application are merely descriptive and do not represent the superiority or inferiority of the embodiments.

[0182] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0183] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods, such as: multiple units or components can be combined, or integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the various components shown or discussed can be through some interfaces, and the indirect coupling or communication connection between devices or units can be electrical, mechanical, or other forms.

[0184] The units described above as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units; some or all of the units may be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, the functional units in the embodiments of this application may all be integrated into one processing unit, or each unit may be a separate unit, or two or more units may be integrated into one unit; the integrated unit may be implemented in hardware or in a combination of hardware and software functional units.

[0185] Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps of the above method embodiments. The aforementioned storage medium includes various media that can store program code, such as mobile storage devices, read-only memory (ROM), magnetic disks, or optical disks.

[0186] Alternatively, if the integrated units described above are implemented as software functional modules and sold or used as independent products, they can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence or the part that contributes to related technologies, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, ROM, magnetic disks, or optical disks.

[0187] The above description is merely an embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A cell balancing method, characterized in that, The method includes: Based on the current value of the battery pack and the sleep duration of the battery pack, determine whether the battery pack meets the first condition for the equalization switch to be turned on; Based on the voltage value of each cell in the battery pack and the temperature value of the battery pack, determine whether the corresponding cell meets the second condition for the equalization switch to be turned on; If the battery pack meets the first condition, the cells that meet the second condition are selected as candidate cells to be balanced. Based on the state of charge value of each cell to be balanced and the balancing current value of the battery pack, the first balancing time of the corresponding cell to be balanced is determined. The shorter of the first balancing time and the preset balancing time for each battery cell to be balanced is determined as the balancing time for the corresponding battery cell to be balanced. According to the balancing time of the cell to be balanced, the balancing switch of the corresponding cell to be balanced is set to the on state.

2. The method based on claim 1, characterized in that, The first condition includes a first sub-condition or a second sub-condition. Determining whether the battery pack meets the first condition for activating the equalization switch, based on the current value of the battery pack and the sleep duration of the battery pack, includes: Determine whether the sleep duration of the battery pack is within a first preset duration; if the sleep duration of the battery pack is within the first preset duration, determine that the battery pack meets the first sub-condition for the equalization switch to be turned on; Determine whether the current value of the battery pack is within a preset current range within a second preset time period; if the current value of the battery pack is within the preset current range within the second preset time period, determine that the battery pack meets the second sub-condition for the equalization switch to be turned on. If the battery pack satisfies either the first sub-condition or the second sub-condition, it is determined that the battery pack satisfies the first condition for the equalization switch to be turned on.

3. The method based on claim 1, characterized in that, When the battery cell system type is ternary lithium battery cell, the second condition includes a third sub-condition or a fourth sub-condition. Determining whether a corresponding battery cell meets the second condition for activating the equalization switch based on the voltage value of each cell in the battery pack and the temperature value of the battery pack includes: If the battery cell is determined to be a ternary lithium battery cell, the maximum voltage value and the minimum voltage value are determined based on the voltage values ​​of all the battery cells in the battery pack. The difference between the voltage value of each cell in the battery pack and the minimum voltage value is determined as the cell voltage difference of the corresponding cell. Determine whether the maximum voltage value is within a preset voltage range, and whether the cell voltage difference of each cell is within a first preset cell voltage difference range; If the maximum voltage value is within a preset voltage range and the cell voltage difference of each cell is within a first preset cell voltage difference range, then the corresponding cell is determined to meet the third sub-condition for the equalization switch to be turned on. Determine whether the maximum voltage value is outside the preset voltage range, and whether the cell voltage difference of each cell is within the second preset cell voltage difference range; If the maximum voltage value is not within the preset voltage range and the cell voltage difference of each cell is within the second preset cell voltage difference range, then the corresponding cell is determined to meet the fourth sub-condition for the equalization switch to be turned on. If each of the aforementioned cells satisfies the third or fourth sub-condition, it is determined that the corresponding cell satisfies the second condition for the equalization switch to be turned on.

4. The method according to claim 1, characterized in that, When the cell system type is lithium iron phosphate cell, determining whether the corresponding cell meets the second condition for activating the equalization switch based on the voltage value of each cell in the battery pack and the temperature value of the battery pack includes: Determine whether the state of charge (SOC) value of each cell in the battery pack is within a first preset SOC range and whether the temperature value is within a preset temperature range; if the SOC value of each cell in the battery pack is within the first preset SOC range and the temperature value is within the preset temperature range, determine that the corresponding cell meets the second condition for the equalization switch to be turned on. or, Determine whether the state of charge (SOC) value of each cell in the battery pack is within a second preset SOC range and whether the temperature value is within a preset temperature range; if the SOC value of each cell in the battery pack is within the second preset SOC range and the temperature value is within the preset temperature range, determine that the corresponding cell meets the second condition for the equalization switch to be turned on. Wherein, the first preset charge range is greater than or equal to 95, and the second preset charge range is less than or equal to 20.

5. The method according to claim 1, characterized in that, The step of determining the first balancing time for the corresponding cell based on the state of charge value of each cell to be balanced and the balancing current value of the battery pack includes: Based on the state of charge value of each cell to be balanced and the factory-calibrated value of the cell capacity of the corresponding cell to be balanced, the initial capacity difference of the corresponding cell to be balanced is determined. Based on the initial capacity difference of each of the cells to be balanced and the balancing current value of the battery pack, the second balancing time of the corresponding cell to be balanced is determined. The result of dividing the second balancing time of each cell to be balanced by the preset balancing duty cycle is determined as the first balancing time of the corresponding cell.

6. The method based on claim 5, characterized in that, The determination of the initial capacity difference for each cell to be balanced, based on the state of charge value of each cell and the factory-calibrated capacity value of the corresponding cell, includes: Based on the voltage value of each of the cells to be balanced and the temperature of the battery pack, the state of charge value of the corresponding cell to be balanced is determined. The minimum state of charge value is determined based on the state of charge values ​​of all cells in the battery pack. The difference between the state of charge value of each cell to be balanced and the minimum state of charge value is determined as the state of charge difference of the corresponding cell to be balanced. The initial capacity difference of the corresponding cell to be balanced is determined by multiplying the difference in the state of charge of each cell to be balanced by the factory-calibrated capacity value of the corresponding cell to be balanced.

7. The method according to any one of claims 1 to 6, characterized in that, During the cell balancing process, the method includes: If the current parameter values ​​of the battery pack meet the first preset range, turn off the balancing switch of the cells in the battery pack that are in a balanced state. If the current parameter values ​​of the cell in each equilibrium state meet the second preset range, the equilibrium switch of the cell in the corresponding equilibrium state is turned off.

8. The method according to any one of claims 1 to 6, characterized in that, Before determining that the battery pack meets the first condition for the equalization switch to be turned on, the method further includes: Based on the current parameter data values ​​of the battery pack and the preset parameter threshold, determine the relationship between the current parameter data values ​​of the battery pack and the preset parameter threshold; If the parameter data value is determined to be within the range of a preset parameter threshold, the validity of the parameter data value is determined based on the parameter data value and the validity flag bit of the parameter.

9. A cell balancing device, characterized in that, The device includes: The first determining module is used to determine whether the battery pack meets the first condition for the equalization switch to be turned on based on the current value of the battery pack and the sleep duration of the battery pack. The second determining module is used to determine whether the corresponding cell meets the second condition for the equalization switch to be turned on, based on the voltage value of each cell in the battery pack and the temperature value of the battery pack. The third determining module is used to, when the battery pack meets the first condition, take the cells that meet the second condition as candidate cells to be balanced, and determine the first balancing time of the corresponding cells to be balanced based on the state of charge value of each cell to be balanced and the balancing current value of the battery pack. The fourth determining module is used to determine the smaller of the first equalization time and the preset equalization time for each of the cells to be equalized as the equalization time for the corresponding cell to be equalized. The setting module is used to set the balancing switch of the corresponding battery cell to the on state according to the balancing time of the battery cell to be balanced.

10. A computer device comprising a memory and a processor, the memory storing a computer program executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the method according to any one of claims 1 to 8.

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