Battery cell equalization method and device, computer equipment and storage medium

Abstract

The invention discloses a battery monomer equalization method, which comprises the following steps: acquiring current or voltage of each battery monomer, and calculating the charge state of each battery monomer according to the current or voltage of each battery monomer; when the relative voltage difference between the voltage of each battery monomer and a preset target voltage is greater than a monomer voltage difference threshold value, setting a voltage difference equalization identifier bit of the corresponding battery monomer as an effective voltage difference equalization identifier; when the relative state-of-charge difference between the state-of-charge of each single battery and the target state-of-charge is greater than zero, setting the state-of-charge difference equalization identifier bit of the corresponding single battery as an effective state-of-charge difference equalization identifier; when the voltage difference equalization identifier and the charge state difference equalization identifier of the single battery are effective, the final equalization flag bit of the single battery is effective, the equalization time of the single battery is calculated, and equalization processing of the single battery is controlled according to the equalization time; therefore, the battery equalization effect is improved, and the problem of over-discharge of the battery cells is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of power batteries, and in particular to a method, device, computer equipment, and storage medium for balancing battery cells. Background Art

[0002] As a core component of new energy, the performance of power batteries is attracting increasing attention. Due to the influence of the manufacturing process, there are inconsistencies in internal resistance, capacity, and self-discharge rate between individual cells. After the individual cells are connected in series to form a power battery, these inconsistencies are exacerbated during use due to the different environments in which the cells are exposed. This can affect the actual performance of the power battery, resulting in reduced charge and discharge power and actual available power. Severe cell inconsistency can also lead to the risk of overcharging or over-discharging the individual cells. Therefore, the battery management system (BMS) needs to have a cell balancing function. When the risk of cell inconsistency increases, the balancing function can be activated promptly to reduce the inconsistency between power cells.

[0003] In existing technology, passive battery balancing typically uses cell voltage as the control target for balancing. After the battery system rests for a certain period and wakes up again, the BMS determines the voltage differential between the battery cells. If the voltage differential exceeds a preset threshold, the balancing switch is turned on. This continues until the cell voltage differential within the battery pack decreases to the target threshold, at which point the balancing switch is turned off. This method, which uses only cell voltage differential as the condition for turning balancing on and off, is prone to two extreme situations: inaccurately setting the balancing off condition, causing the balancing switch to be turned off before balancing is complete, resulting in poor cell balancing; or it can easily lead to over-discharge of cells due to over-balancing, which affects battery life. Summary of the Invention

[0004] Embodiments of the present invention provide a battery cell balancing method, apparatus, computer device, and storage medium to solve the problem of poor balancing effect or cell over-discharge caused by using a single cell voltage as a control target for turning on or off balancing in the prior art.

[0005] In one embodiment, a method for balancing battery cells is provided, comprising: Obtaining the current or voltage of each battery cell, and calculating the state of charge of each battery cell according to the current or voltage of each battery cell; When the relative voltage difference between the voltage of each battery cell and the preset target voltage is greater than a preset cell voltage difference threshold, setting the voltage difference balance flag of the corresponding battery cell to a valid voltage difference balance flag; When the relative charge state difference between the state of charge of each battery cell and the preset target state of charge is greater than zero, setting the state of charge difference balancing flag of the corresponding battery cell to a valid state of charge difference balancing flag; When the voltage difference equalization flag and the state of charge difference equalization flag of the battery cell are both valid, the final equalization flag of the battery cell is valid, and the equalization time of the battery cell is calculated, and the equalization processing of the battery cell is controlled according to the equalization time.

[0006] In one embodiment, a battery cell balancing device includes: A cell state of charge calculation module, configured to obtain the current or voltage of each battery cell and calculate the state of charge of each battery cell based on the current or voltage of each battery cell; a voltage difference equalization flag setting module, configured to set the voltage difference equalization flag of the corresponding battery cell to a valid voltage difference equalization flag when the relative voltage difference between the voltage of each battery cell and a preset target voltage is greater than a preset cell voltage difference threshold; a state of charge difference balancing flag setting module, configured to set the state of charge difference balancing flag of the corresponding battery cell to a valid state of charge difference balancing flag when the relative charge state difference between the state of charge of each battery cell and a preset target state of charge is greater than zero; The balancing judgment module is used to determine that, when both the voltage difference balancing flag and the state of charge difference balancing flag of the battery cell are valid, the final balancing flag of the battery cell is valid, calculate the balancing time of the battery cell, and control the balancing processing of the battery cell according to the balancing time; the cell balancing flag of the battery cell is determined according to the voltage difference balancing flag and the state of charge difference balancing flag of the battery cell.

[0007] In one embodiment, a computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the above-mentioned battery cell balancing method is implemented.

[0008] In one embodiment, a computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the computer program implements the above-mentioned battery cell balancing method.

[0009] The above-mentioned battery cell balancing method, device, computer equipment and storage medium use the dual parameters of cell voltage and state of charge to perform battery cell balancing judgment, use the preset cell voltage difference threshold to measure the relative voltage difference between the cell voltage and the target voltage, and determine the voltage difference balancing flag of the battery cell; use the preset target state of charge to measure the relative charge state difference between the state of charge and the battery cell, and determine the state of charge difference balancing flag of the cell battery, and then use the voltage difference balancing flag and the state of charge difference balancing flag of the battery cell to combine and judge whether to turn on the battery cell balancing switch, which can more accurately identify the cell that needs to be balanced, improve the battery balancing effect, and avoid the problem of cell over-discharge. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0011] Figure 1 This is a schematic diagram of an application environment of a battery cell balancing method according to an embodiment of the present invention; Figure 2 is a flow chart of a battery cell balancing method according to an embodiment of the present invention; Figure 3 is a schematic diagram of a battery cell balancing device according to an embodiment of the present invention; Figure 4 FIG. 1 is a schematic diagram of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0012] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0013] The embodiment of the present invention provides a method for balancing battery cells, which can be applied as follows: Figure 1 Specifically, the balancing method is applied in a battery management system, which includes Figure 1The client and server shown communicate over a network to implement battery cell balancing control. The client, also known as the user end, is the program that corresponds to the server and provides local services to clients. The client can be installed on, but is not limited to, various personal computers, laptops, smartphones, tablets, and portable wearable devices. The server can be implemented as a standalone server or a server cluster consisting of multiple servers.

[0014] In one embodiment, if Figure 2 As shown, a method for balancing battery cells is provided, which is applied in Figure 1 The server in the car or the control terminal in the car is used as an example to illustrate, including the following steps: S201, obtaining the current or voltage of each battery cell, and calculating the state of charge of each battery cell according to the current or voltage of each battery cell; Among them, the most original data with higher frequency can be obtained based on the sampling of the BMS bottom sampling chip and sensors of the battery system, including: the cell voltage CellV[n] (CellV1, CellV2, ..., CellVn) and current I of the battery pack with a string number of n. The state of charge of each battery cell is calculated using the ampere-hour integration method and the current of each battery cell obtained; or, the state of charge of each battery cell is calculated using the open circuit voltage method and the voltage of each battery cell obtained, combined with the SOC-OCV curve provided by the battery cell manufacturer. Specifically, the ampere-hour integration method is to record the current and time of the battery cell during the charging or discharging process, calculate the amount of electricity that has been discharged or charged in the battery cell by integration (in the discrete case, the summation can be used for approximation), and then combine it with the initial state of charge to obtain the current state of charge.

[0015] In one example, after step S201, preconditions for entering into the balance judgment may be set, including: First condition: when it is determined that the current I of the battery system is less than a preset threshold value Icb and the duration exceeds a preset threshold value tcb, it is determined that the voltage of the battery cell is in a nearly stable state; Second condition: when the sleep time TSleep after the system wakes up from sleep mode recorded by the BMS storage unit is greater than the preset threshold tslp, it is determined that the battery cell is in a fully resting state.

[0016] That is, before the battery cell balancing is started, if one of the above two conditions is determined to be met, which is equivalent to if the battery cell is in a nearly stable state or a sufficiently static state, the balancing judgment of the following steps S202 to S204 can be performed. Otherwise, the process will proceed again after the conditions are met.

[0017] S202, when the relative voltage difference between the voltage of each battery cell and the preset target voltage is greater than a preset cell voltage difference threshold, setting the voltage difference balancing flag of the corresponding battery cell to a valid voltage difference balancing flag; Among them, after determining the voltage of each of the battery cells, a target voltage for measuring the equalization flag is preset, and the relative voltage difference between the voltage of each of the battery cells and the preset target voltage is compared. If the relative voltage difference is greater than the preset cell voltage difference threshold, the voltage difference equalization flag CellVFlg[i] is set to a valid voltage difference equalization flag, for example, CellVFlg[i]=1; if the relative voltage difference is not greater than the preset cell voltage difference threshold, the voltage difference equalization flag CellVFlg[i] is set to an invalid voltage difference equalization flag, for example, CellVFlg[i]=0.

[0018] The preset cell voltage differential threshold above represents the tolerable cell voltage differential threshold for the battery system. This threshold can be calibrated based on temperature. Typically, at low temperatures, the battery's internal resistance is higher, and the corresponding voltage differential increases, so the threshold can be set in segments. For example, the cell voltage differential threshold Vcb at room temperature is 20mV, while at low temperatures, the cell voltage differential threshold Vcb is 30mV.

[0019] S203, when the relative state of charge difference between the state of charge of each battery cell and a preset target state of charge is greater than zero, setting the state of charge difference balancing flag of the corresponding battery cell to a valid state of charge difference balancing flag; Among them, after determining the state of charge of each of the battery cells, a target state of charge is preset for measuring the state of charge difference balancing flag, and the relative charge state difference between the state of charge of each of the battery cells and the target state of charge is compared. When the relative charge state difference is greater than zero, the state of charge difference balancing flag CellSocFlg[i] is set to a valid state of charge difference balancing flag, for example, CellSocFlg[i]=1; when the relative charge state difference is not greater than zero, the state of charge difference balancing flag CellSocFlg[i] is set to an invalid state of charge difference balancing flag, for example, CellSocFlg[i]=0.

[0020] S204 , when the voltage difference balancing flag and the state of charge difference balancing flag of the battery cell are both valid, the final balancing flag of the battery cell is valid, and the balancing time of the battery cell is calculated, and the balancing process of the battery cell is controlled according to the balancing time.

[0021] The balancing switch of the battery cell can be turned on based on the valid voltage difference balancing flag and the valid state of charge difference balancing flag of the battery cell, and the timing of turning off the balancing switch can be determined based on the calculated balancing time. When the voltage difference balancing flag CellVFlg[i] of the battery cell is valid and the state of charge difference balancing flag CellSocFlg[i] is valid, the cell balancing flag CellBalFlg[i] of the battery cell is set to the valid cell balancing flag, that is, CellBalFlg[i] = CellVFlg[i] & CellSocFlg[i].

[0022] The battery cell balancing method of this embodiment uses the dual parameters of cell voltage and state of charge to determine cell balancing. A preset cell voltage difference threshold is used to measure the relative voltage difference between the cell voltage and the target voltage to determine the cell voltage difference balancing flag. A preset target state of charge is used to measure the relative charge state difference between the cell state of charge and the cell state of charge to determine the cell state of charge difference balancing flag. The cell voltage difference balancing flag and the state of charge difference balancing flag are then used to determine whether to enable the cell balancing switch. This allows for more accurate identification of cells requiring balancing, improves battery balancing effectiveness, and avoids the problem of cell over-discharge. Furthermore, the time required for cell balancing is quantified, making the balancing target more specific, further improving the efficiency of cell balancing, and preventing further expansion of cell inconsistencies that could affect battery performance.

[0023] In one embodiment, in step S202, the step of determining the target voltage includes: S301, determining a maximum cell voltage and an average cell voltage of the battery cells according to the voltages of the battery cells; S302 : Perform weighted calculation on the maximum cell voltage and the average cell voltage according to a preset maximum cell voltage weight coefficient and a preset average cell voltage weight coefficient to obtain a target voltage.

[0024] The preset average cell voltage weight coefficient is equivalent to a voltage tolerance coefficient. In order to make the voltage balance tend to the average voltage, the average cell voltage weight coefficient can be set close to 0.5, for example, b = 0.55. Different battery characteristics can be calibrated in practice.

[0025] The battery cell balancing method of this embodiment performs weighted calculation on the maximum cell voltage and the average cell voltage based on the maximum cell voltage weight coefficient and the preset average cell voltage weight coefficient, and determines the cell voltage target voltage for comparison with the cell voltage difference threshold, thereby more accurately obtaining the cell relative voltage difference and ensuring the reliability of the setting of the voltage difference balancing flag of the battery cell.

[0026] Exemplarily, the target voltage is calculated as follows: GoalVolt = δ*CellV avg +(1-δ)*CellV max Among them, GoalVolt is the target voltage, δ is the preset average cell voltage weight coefficient, CellV avg is the average cell voltage of the battery cell, (1-δ) is the preset maximum cell voltage weight coefficient, CellV max It is the maximum cell voltage of the battery cell.

[0027] The battery cell balancing method of this embodiment uses the maximum cell voltage weight coefficient and the preset average cell voltage weight coefficient to perform weighted summation on the maximum cell voltage and the average cell voltage to determine the cell voltage target voltage for comparison with the cell voltage difference threshold, thereby more accurately obtaining the cell relative voltage difference and ensuring the reliability of the setting of the voltage difference balancing flag of the battery cell.

[0028] In one embodiment, in step 203, the step of determining the target state of charge includes: S401, determining a maximum state of charge and a minimum state of charge of the battery cells according to the state of charge of the battery cells; S402 : Calculate a target state of charge according to a preset maximum cell state of charge weight coefficient and a preset minimum cell state of charge weight coefficient.

[0029] Among them, in order to prevent excessive or abnormal balancing, the preset minimum single state of charge weight coefficient is between 0.3 and 0.8, and the maximum single state of charge weight coefficient is between 0.7 and 0.2. The coefficient can also be actually calibrated according to the characteristics of the battery pack.

[0030] The battery cell balancing method of this embodiment performs a weighted calculation on the maximum cell state of charge and the minimum cell state of charge based on the maximum cell state of charge weight coefficient and the minimum cell state of charge weight coefficient to determine a target state of charge for comparison with the battery cell state of charge, thereby ensuring the reliability of the setting of the single cell state of charge difference balancing flag.

[0031] Exemplarily, the target state of charge is calculated as follows: GoalSoc = α*CellSOC min + (1-α) * CellSOC max Among them, GoalSoc is the target state of charge, α is the preset minimum cell state of charge weight coefficient, CellSOCmin is the minimum state of charge of the battery cell, (1-α) is the preset maximum state of charge weight coefficient, CellSOC max It is the maximum single cell state of charge of the battery cell.

[0032] The battery cell balancing method of this embodiment performs a weighted summation of the maximum cell state of charge and the minimum cell state of charge based on the maximum cell state of charge weight coefficient and the minimum cell state of charge weight coefficient to determine a target state of charge for comparison with the battery cell state of charge, thereby further ensuring the reliability of the setting of the single cell state of charge difference balancing flag.

[0033] In one embodiment, in step S204, calculating the balancing time of the battery cells includes: S501, obtaining the relative state of charge difference of the battery cells, the maximum balancing current used to characterize the balancing capability of the battery system, the duty cycle of balancing current control, the initial capacity of the battery, and the battery life factor; S502, calculating the total balancing charge required for this balancing according to the relative state of charge difference of the battery cells, the initial capacity of the battery, and the battery life factor; S503: Calculate an effective balancing current per unit time according to the maximum balancing current and the duty cycle of the balancing current control; S504 : Obtaining a balancing time of the battery cell according to a ratio between the total balancing charge and the effective balancing current.

[0034] The initial battery capacity and battery life factor can be obtained from data provided by the battery cell manufacturer. The maximum balancing current and duty cycle for balancing current control, which characterize the balancing capability of the battery system, can be obtained from data within the battery system where the battery cell is located. Both are customizable. The maximum balancing current ranges from 30-100mA, and the PWM duty cycle for balancing current control ranges from 20%-50%. For example, the maximum balancing current range can also be 40-100mA, or 30-90mA, and the duty cycle range can also be 25%-50%, or 30%-50%.

[0035] Specifically, the calculation formula for the balancing time of battery cells is as follows: CellBalTime[i] = DiffSoc[i]* C0 *Soh / (CurrCBmax * ξ) Where CellBalTime[i] is the balancing time of battery cell i, DiffSoc[i] is the relative state of charge difference of battery cell i, C0 is the initial capacity of the battery, Soh is the battery life factor, CurrCBmax is the maximum balancing current, and ξ is the duty cycle of the balancing current control.

[0036] The battery cell balancing method of this embodiment quantifies the time required for cell balancing based on the maximum balancing current and the duty cycle of the balancing current control, which are used to characterize the balancing capability of the battery system. This makes the balancing goal more clear, effectively improves the efficiency of cell balancing, and prevents further expansion of cell inconsistency that affects battery use.

[0037] In one embodiment, in step S204, controlling the balancing process of the battery cells according to the balancing time includes: S601, after turning on the balancing switch of the battery cell, updating the balancing time of the battery cell in real time, and when the balancing time decreases to zero, turning off the balancing switch of the battery cell and setting the cell balancing flag of the corresponding battery cell to an invalid cell balancing flag; S602, after turning on the balancing switch of the battery cell, monitor the maximum temperature of the circuit board of the battery management system in real time. When the maximum temperature of the circuit board exceeds a preset first operating temperature range, temporarily turn off the balancing switches of all battery cells; when the maximum temperature of the circuit board drops to a preset second operating temperature range, turn on the balancing switch of the battery cell.

[0038] Real-time updating of the battery cell balancing time involves setting a first balancing time T1 after turning on the balancing switch. A countdown begins, updating the first balancing time T1 to the second balancing time T2 (equivalent to the first balancing time T1 minus the preset time step), and so on, until the Nth balancing time TN = 0 is reached. Furthermore, after the balancing function is enabled for a battery cell with a valid cell balancing flag, as the balancing time CellBalTime[i] decreases monotonically, when the balancing time reaches 0, the balancing switch for that battery cell is turned off, and the corresponding cell balancing flag CellBalFlg[i] is set to 0. Furthermore, during the current BMS system wakeup phase, the balancing flags for any uncompleted cells and the remaining required balancing time CellBalTime[i] are stored in the non-volatile EEPROM. Upon the next BMS wakeup, balancing for the corresponding battery cell will resume until balancing is complete for all cells with valid cell balancing flags.

[0039] The battery cell balancing method of this embodiment, after the battery system goes into sleep mode, stores the unbalanced cell balancing flag and the remaining balancing time in the non-volatile EEPROM memory unit. Balancing resumes upon the next wakeup, simplifying the balancing judgment process and making cell balancing more thorough, eliminating the need for frequent judgments and activations. Furthermore, the balancing algorithm of the present invention is simple and flexible, requiring no high computing power from the hardware platform, making it well suited for the development of new energy vehicle battery systems. Within the existing battery system architecture, there is no need for additional sensors, the hardware platform can be universal, and the software can be adapted to different batteries without incurring additional development costs.

[0040] In one embodiment, the balancing method further includes: The controller is used to set the voltage difference equalization flag and the state of charge difference equalization flag, determine the final equalization flag, calculate the equalization time of the battery cell, and control the equalization processing of the battery cell according to the equalization time.

[0041] The controller may be implemented as a control chip in a battery management system to obtain the current or voltage of each battery cell and perform corresponding calculations and judgments.

[0042] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0043] In one embodiment, a battery cell balancing device is provided, which corresponds to the balancing method in the above embodiment. Figure 3 As shown, the balancing device includes a single-cell state of charge calculation module 31, a voltage difference balancing flag setting module 32, a state of charge difference balancing flag setting module 33, and a balancing judgment module 34. The functional modules are described in detail as follows: A cell state of charge calculation module 31 is used to obtain the current or voltage of each battery cell and calculate the state of charge of each battery cell according to the current or voltage of each battery cell; a voltage difference equalization flag setting module 32, configured to set the voltage difference equalization flag of the corresponding battery cell to a valid voltage difference equalization flag when the relative voltage difference between the voltage of each battery cell and a preset target voltage is greater than a preset cell voltage difference threshold; a state of charge difference balancing flag setting module 33, configured to set the state of charge difference balancing flag of the corresponding battery cell to a valid state of charge difference balancing flag when the relative charge state difference between the state of charge of each battery cell and a preset target state of charge is greater than zero; The balancing judgment module 34 is configured to, when both the voltage difference balancing flag and the state of charge difference balancing flag of the battery cell are valid, determine that the final balancing flag of the battery cell is valid, calculate the balancing time of the battery cell, and control the balancing process of the battery cell according to the balancing time.

[0044] In one embodiment, the voltage difference equalization flag setting module 32 includes: A cell voltage calculation submodule, configured to determine a maximum cell voltage and an average cell voltage of the battery cells according to the voltages of the battery cells; The target voltage weighting submodule is used to perform weighted calculation on the maximum cell voltage and the average cell voltage according to a preset maximum cell voltage weight coefficient and a preset average cell voltage weight coefficient to calculate the target voltage.

[0045] The target voltage is calculated as follows: GoalVolt = δ*CellV avg +(1-δ)*CellV max Among them, GoalVolt is the target voltage, δ is the preset average cell voltage weight coefficient, CellV avg is the average cell voltage of the battery cell, (1-δ) is the preset maximum cell voltage weight coefficient, CellV max It is the maximum cell voltage of the battery cell.

[0046] In one embodiment, the state of charge difference equalization flag setting module 33 includes: a cell state of charge calculation submodule, configured to determine a maximum cell state of charge and a minimum cell state of charge of the battery cells according to the state of charge of each of the battery cells; The target state of charge weighting submodule is used to calculate the target state of charge based on the preset maximum single cell state of charge weight coefficient and the preset minimum single cell state of charge weight coefficient.

[0047] The target state of charge is calculated as follows: GoalSoc = α*CellSOC min + (1-α) * CellSOC max Among them, GoalSoc is the target state of charge, α is the preset minimum cell state of charge weight coefficient, CellSOC min is the minimum state of charge of the battery cell, (1-α) is the preset maximum state of charge weight coefficient, CellSOC max It is the maximum single cell state of charge of the battery cell.

[0048] In one embodiment, the balance determination module 34 includes: An acquisition submodule, configured to obtain the relative state of charge difference of the battery cells, a maximum balancing current for characterizing the balancing capability of the battery system, a duty cycle for balancing current control, an initial battery capacity, and a battery life factor; A total balancing current calculation submodule is used to calculate the total balancing charge required for this balancing according to the relative state of charge difference of the battery cells, the initial capacity of the battery, and the battery life factor; an effective balancing current calculation submodule, configured to calculate an effective balancing current per unit time according to the maximum balancing current and the duty cycle of the balancing current control; The balancing time calculation submodule is configured to obtain the balancing time of the battery cell according to the ratio between the total balancing charge and the effective balancing current.

[0049] In one embodiment, the balance determination module 34 further includes: A cell balancing flag setting submodule is used to update the balancing time of the battery cell in real time after turning on the balancing switch of the battery cell, and when the balancing time decreases to zero, turn off the balancing switch of the battery cell and set the cell balancing flag of the corresponding battery cell to an invalid cell balancing flag; The balancing pause control submodule is used to monitor the maximum temperature of the circuit board of the battery management system in real time after turning on the balancing switch of the battery cell. When the maximum temperature of the circuit board exceeds a preset first operating temperature range, the balancing switches of all battery cells are temporarily turned off; when the maximum temperature of the circuit board drops to a preset second operating temperature range, the balancing switches of the battery cells are turned on.

[0050] In one embodiment, it further includes: The controller is configured to set a voltage difference equalization flag and the state of charge difference equalization flag, determine the final equalization flag, calculate the equalization time of the battery cells, and control the equalization processing of the battery cells according to the equalization time.

[0051] In one embodiment, the maximum balancing current ranges from 30 to 100 mA, and the duty cycle for balancing current control ranges from 20% to 50%.

[0052] The specific definition of the battery cell balancing device can be found in the definition of the battery cell balancing method above and will not be repeated here. The various modules in the above-mentioned battery cell balancing device can be implemented in whole or in part through software, hardware, or a combination thereof. Each of the above-mentioned modules can be embedded in or independent of the processor of the computer device in hardware form, or can be stored in the memory of the computer device in software form, so that the processor can call and execute the corresponding operations of each of the above modules.

[0053] In one embodiment, a computer device is provided. The computer device may be a server, and its internal structure diagram may be as follows: Figure 4 As shown. The computer device includes a processor, a memory, a network interface, and a database connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and computer program in the non-volatile storage medium. The database of the computer device is used for the balancing control function of battery cells. The network interface of the computer device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, a method for balancing battery cells is implemented.

[0054] In one embodiment, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the battery cell balancing method in the above embodiment is implemented, for example: Figure 2 Alternatively, when the processor executes the computer program, the functions of each module / unit in the embodiment of the battery cell balancing device are realized, for example, Figure 3 To avoid repetition, the equalization function shown will not be described here.

[0055] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the battery cell balancing method in the above embodiment is implemented, for example Figure 2 To avoid repetition, the steps S201-S204 are not described here. Alternatively, when the computer program is executed by the processor, the functions of the modules / units in the embodiment of the battery cell balancing device are realized, for example, Figure 3 To avoid repetition, the equalization function shown will not be described here.

[0056] Those skilled in the art will understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0057] Those skilled in the art will clearly understand that for the sake of convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0058] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. A method for balancing a battery cell, characterized in that: The battery cell balancing method includes: Obtaining the current or voltage of each battery cell, and calculating the state of charge of each battery cell according to the current or voltage of each battery cell; When the relative voltage difference between the voltage of each battery cell and the preset target voltage is greater than a preset cell voltage difference threshold, setting the voltage difference balance flag of the corresponding battery cell to a valid voltage difference balance flag; When the relative charge state difference between the state of charge of each battery cell and the preset target state of charge is greater than zero, setting the state of charge difference balancing flag of the corresponding battery cell to a valid state of charge difference balancing flag; When the voltage difference equalization flag and the state of charge difference equalization flag of the battery cell are both valid, the final equalization flag of the battery cell is valid, and the equalization time of the battery cell is calculated, and the equalization processing of the battery cell is controlled according to the equalization time.

2. The battery cell balancing method according to claim 1, characterized in that: The step of determining the target voltage includes: Determining the maximum cell voltage and the average cell voltage of the battery cells according to the voltages of the battery cells; According to a preset maximum cell voltage weight coefficient and a preset average cell voltage weight coefficient, a weighted calculation is performed on the maximum cell voltage and the average cell voltage to obtain a target voltage.

3. The battery cell balancing method according to claim 1, characterized in that: The step of determining the target state of charge includes: Determining a maximum state of charge and a minimum state of charge of the battery cells according to the state of charge of each battery cell; The target state of charge is obtained according to a preset maximum cell state of charge weight coefficient and a preset minimum cell state of charge weight coefficient.

4. The battery cell balancing method according to claim 1, wherein: Calculating the balancing time of the battery cells includes: Obtaining the relative state of charge difference of the battery cells, the maximum balancing current used to characterize the balancing capability of the battery system, the duty cycle for balancing current control, the initial capacity of the battery, and the battery life factor; Calculate the total balancing charge required for this balancing according to the relative state of charge difference of the battery cells, the initial capacity of the battery, and the battery life factor; Calculating an effective balancing current per unit time according to the maximum balancing current and a duty cycle of the balancing current control; The balancing time of the battery cell is obtained according to the ratio between the total balancing charge and the effective balancing current.

5. The battery cell balancing method according to claim 4, characterized in that: Controlling the balancing process of the battery cells according to the balancing time includes: After turning on the balancing switch of the battery cell, updating the balancing time of the battery cell in real time; when the balancing time decreases to zero, turning off the balancing switch of the battery cell and setting the cell balancing flag of the corresponding battery cell to an invalid cell balancing flag; After turning on the balancing switch of the battery cell, the maximum temperature of the circuit board of the battery management system is monitored in real time. When the maximum temperature of the circuit board exceeds the preset first operating temperature range, the balancing switches of all battery cells are temporarily turned off; when the maximum temperature of the circuit board drops to within the preset second operating temperature range, the battery cell is turned on.

6. The battery cell balancing method according to claim 1, characterized in that: The balancing method further comprises: The controller is used to set the voltage difference equalization flag and the state of charge difference equalization flag, determine the final equalization flag, calculate the equalization time of the battery cell, and control the equalization processing of the battery cell according to the equalization time.

7. The battery cell balancing method according to claim 4, characterized in that: The maximum balancing current ranges from 30 to 100 mA, and the duty cycle for balancing current control ranges from 20% to 50%.

8. A battery cell balancing device, characterized in that: The balancing includes: A cell state of charge calculation module, configured to obtain the current or voltage of each battery cell and calculate the state of charge of each battery cell based on the current or voltage of each battery cell; a voltage difference equalization flag setting module, configured to set the voltage difference equalization flag of the corresponding battery cell to a valid voltage difference equalization flag when the relative voltage difference between the voltage of each battery cell and a preset target voltage is greater than a preset cell voltage difference threshold; a state of charge difference balancing flag setting module, configured to set the state of charge difference balancing flag of the corresponding battery cell to a valid state of charge difference balancing flag when the relative charge state difference between the state of charge of each battery cell and a preset target state of charge is greater than zero; The balancing judgment module is configured to, when both the voltage difference balancing flag and the state of charge difference balancing flag of the battery cell are valid, determine that the final balancing flag of the battery cell is valid, calculate the balancing time of the battery cell, and control the balancing process of the battery cell according to the balancing time.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the battery cell balancing method according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the battery cell balancing method according to any one of claims 1 to 7 is implemented.

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