Equalization methods, devices, equipment and media

Abstract

This application discloses a balancing method, apparatus, device, and medium, belonging to the field of energy storage technology. The balancing method includes determining the target cell to be balanced based on the voltage of multiple cells electrically connected to a battery management system; charging and discharging the multiple cells, balancing the target cell within a preset charge-discharge range, stopping balancing the target cell outside the preset charge-discharge range while continuing charge-discharge; and identifying outlier cells with large polarization resistance differences based on the voltage of each cell. By employing a strategy of balancing within a preset charge-discharge range and stopping balancing outside the preset charge-discharge range, the voltage deviation caused by differences in polarization resistance is specifically amplified, enabling precise location of outlier cells with large differences in polarization resistance.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to a balancing method, apparatus, equipment and medium. Background Technology

[0002] In applications such as lithium-ion battery energy storage systems and electric vehicles, batteries typically consist of dozens to thousands of individual cells connected in series and parallel to form battery packs (or battery stacks) to provide the required voltage and capacity. Due to subtle differences in manufacturing processes, material batches, and usage environments, even cells of the same model cannot have completely identical internal parameters (such as capacity, internal resistance, and self-discharge rate). This inherent inconsistency between cells is one of the core problems that battery management systems need to address.

[0003] In related technologies, a common approach is to use the static parameters of the battery cells as the basis for screening and grouping. This involves measuring the open-circuit voltage, AC internal resistance, and nominal capacity of the cells when they are at rest or without load, and grouping cells with similar parameters together. While this method ensures that the battery pack is basically consistent in its initial state, it has a fundamental limitation: it cannot effectively identify and evaluate the performance differences of the cells under dynamic operating conditions, especially the dynamic internal resistance differences caused by electrochemical polarization.

[0004] When charging and discharging current flows through a battery cell, a polarization effect occurs inside, causing the terminal voltage to deviate from its equilibrium potential. This portion of the equivalent internal resistance caused by the polarization effect is called polarization internal resistance. Cells with abnormal polarization internal resistance (e.g., due to intensified internal side reactions, abnormal SEI film growth, or decreased material activity leading to high polarization internal resistance) become a "weak link" in the battery pack after it is put into actual operation. During continuous dynamic cycling, this cell will reach the charging or discharging cutoff voltage more quickly, causing the entire battery pack to terminate charging and discharging prematurely, resulting in reduced usable capacity. Simultaneously, the abnormal voltage difference will trigger the battery management system to frequently perform energy balancing, increasing system losses. More seriously, cells with excessively high polarization internal resistance will generate more heat under the influence of current, creating a temperature difference with other cells, accelerating performance degradation, and even posing a risk of thermal runaway. Summary of the Invention

[0005] This application provides an equalization method, apparatus, device, and medium to at least partially solve the above-mentioned technical problems.

[0006] To achieve the above objectives, according to a first aspect of this application, an equilibrium method is provided, comprising: S1. Determine the target cell to be balanced based on the voltage of the multiple cells electrically connected to the battery management system. S2. Charge and discharge multiple battery cells (5), and balance the target battery cell within a preset charge and discharge range. Stop balancing the target battery cell outside the preset charge and discharge range and continue charging and discharging. S3. Determine the outlier cells with outlier polarization internal resistance based on the voltage of each cell.

[0007] In some embodiments, by employing a strategy of balancing within a preset charge / discharge range and stopping balancing outside the range, the voltage deviation caused by the difference in polarization internal resistance is amplified in a targeted manner. This allows for the precise location of outlier cells with large differences in polarization internal resistance, reducing problems such as reduced usable battery pack capacity and frequent triggering of the balancing system caused by cell inconsistency. It also reduces the risk of thermal runaway caused by thermal imbalance, while reducing ineffective energy consumption during balancing and component losses. This improves the control accuracy of the battery management system and extends the full life cycle performance and reliability of lithium battery energy storage systems and battery packs for electric vehicles.

[0008] According to a second aspect of this disclosure, an equalization device is provided, applicable to the above-described equalization method. The device includes a sampling module, an equalization module, and a screening module. The sampling module is used to determine a target cell to be equalized based on the voltages of multiple cells electrically connected to a battery management system. The equalization module is used to charge and discharge the multiple cells, equalize the target cell within a preset charge-discharge interval, stop equalizing the target cell outside the preset charge-discharge interval, and continue charging and discharging. The screening module is used to determine outlier cells with outlier polarization internal resistance based on the voltage of each cell.

[0009] It should be noted that the equalization device provided in this application embodiment can implement all the method steps implemented in the above equalization method embodiment and can achieve the same technical effect. Here, the parts that are the same as those in the method embodiment and the beneficial effects will not be described in detail.

[0010] According to a third aspect of this disclosure, an electronic device is provided, which may include: a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other via the communication bus. The processor may invoke a computer program stored in the memory to execute the above-described method.

[0011] It should be noted that the electronic device provided in this application embodiment can implement all the method steps implemented in the above-mentioned equalization method embodiment and can achieve the same technical effect. Here, the parts that are the same as those in the method embodiment and the beneficial effects will not be described in detail.

[0012] According to a fourth aspect of this disclosure, a storage medium is provided that stores a computer program for causing a processor to execute the methods provided in the above embodiments.

[0013] It should be noted that the storage medium provided in this application embodiment can implement all the method steps implemented in the above-mentioned equalization method embodiment and can achieve the same technical effect. Here, the parts that are the same as those in the method embodiment and the beneficial effects will not be described in detail.

[0014] According to a fifth aspect of this disclosure, a computer program product is provided, comprising a computer program that can be stored on a storage medium, and when the computer program is executed by a processor, the computer is able to perform the methods provided in the above embodiments.

[0015] It should be noted that the computer program product provided in this application embodiment can implement all the method steps implemented in the above-mentioned equilibrium method embodiment and can achieve the same technical effect. Here, the parts that are the same as those in the method embodiment and the beneficial effects will not be described in detail.

[0016] In the balancing method of this application embodiment, by using a strategy of balancing within a preset charge / discharge range and stopping balancing outside the range, the voltage deviation caused by the difference in polarization internal resistance is specifically amplified. This can accurately locate outlier cells with large differences in polarization internal resistance, thereby reducing problems such as reduced usable battery pack capacity and frequent triggering of the balancing system caused by inconsistent cells through regrouping. It also reduces the risk of thermal runaway caused by thermal imbalance, reduces ineffective energy consumption and component wear during balancing, improves the control accuracy of the battery management system, and extends the full life cycle performance and reliability of lithium battery energy storage systems and battery packs for electric vehicles.

[0017] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description 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 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.

[0018] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings, wherein the same reference numerals in the following description denote the same parts.

[0019] Figure 1 This is a schematic flowchart of the balancing method provided in an embodiment of this application; Figure 2 This is a diagram showing the voltage change of a battery cell during a single charge and discharge cycle, provided in an embodiment of this application. Figure 3 This is another cell voltage change diagram provided in an embodiment of this application during a charge and discharge cycle; Figure 4 This is a flowchart illustrating steps S301 and S302 provided in an embodiment of this application; Figure 5 This is a flowchart illustrating steps S101 and S102 provided in an embodiment of this application; Figure 6 This is a flowchart illustrating steps S1011 to S1013 provided in the embodiments of this application; Figure 7 This is a topology diagram of the battery management system provided in an embodiment of this application; Figure 8 This is a topology diagram of the battery module portion provided in an embodiment of this application; Figure 9 This is a flowchart illustrating steps S1014 and S1015 provided in an embodiment of this application; Figure 10 This is a flowchart illustrating steps S201 and S202 provided in an embodiment of this application; Figure 11 This is a flowchart illustrating steps S303 and S304 provided in an embodiment of this application; Figure 12 This is a flowchart illustrating step S203 provided in an embodiment of this application; Figure 13 This is a flowchart illustrating step S204 provided in an embodiment of this application; Figure 14 This is a flowchart illustrating step S205 provided in an embodiment of this application; Figure 15 This is a flowchart illustrating step S2035 provided in an embodiment of this application; Figure 16 This is a schematic diagram of the equalization device provided in an embodiment of this application; Figure 17 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application.

[0020] Explanation of reference numerals in the attached figures: 1. Slave controller; 2. Master controller; 3. Human-machine interface; 4. Battery module; 5. Battery cell; 6. Communication cable; 410. Sampling module; 420. Equalization module; 430. Filtering module; 510. Processor; 520. Communication interface; 530. Memory; 540. Communication bus. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the protection scope of this application.

[0022] The first aspect of this application, with reference to Figure 1 This disclosure provides an equalization method, which includes S1, S2 and S3. S1: Determine the target cell to be equalized based on the voltage of multiple cells 5 electrically connected to the battery management system.

[0023] Understandably, the battery management system collects the voltage data of all individual cells 5 in real time, calculates the average voltage of all cells 5, and then calculates the difference between the voltage of each cell 5 and the average voltage. Cells 5 with a difference greater than the preset equalization activation threshold are identified as target cells to be equalized. Specifically, this includes cells 5 with a voltage higher than the average voltage and a difference exceeding the threshold that need to be discharged for equalization, and cells 5 with a voltage lower than the average voltage and a difference exceeding the threshold that need to be charged for equalization.

[0024] S2. Charge and discharge multiple battery cells 5, and balance the target battery cell within the preset charge and discharge range. Stop balancing the target battery cell outside the preset charge and discharge range and continue charging and discharging.

[0025] Understandably, the preset charge / discharge range can be characterized by the remaining charge (State of Charge, SOC), expressed as a percentage. For example, during the charging or discharging process, if the SOC is between 5% and 95%, the target cell is balanced. The corresponding balancing operation is performed according to the type of the target cell. For cell 5 that needs to be balanced by charging, energy is replenished through energy transfer. For cell 5 that needs to be balanced by discharging, excess energy is released through energy transfer. During the balancing process, it is necessary to ensure that the voltage of cell 5 is within a safe range.

[0026] S3. Determine the outlier cells with outlier polarization internal resistance based on the voltage of each cell 5.

[0027] Understandably, after charging and discharging are completed, the voltage data of all cells 5 are collected. By calculating the average, maximum and minimum voltage values, cells 5 whose voltage deviates from the average value by more than the preset outlier threshold are identified as outlier cells with outlier polarization internal resistance.

[0028] The balancing method provided in this application is executed by a balancing device, which can be a hardware device independently set in the battery management system (BMS) of the energy storage system, or a software program running in the BMS.

[0029] During battery charging and discharging, cell 5 with high polarization resistance is supplied with the same current as other cells 5. Due to its stronger polarization effect, its voltage rises faster. Only within a preset charge / discharge range (e.g., SOC 5%~95%), if the battery management system detects that its voltage is higher than the average voltage of cells 5 and the difference exceeds the equalization activation threshold, it is identified as a target cell and discharge equalization is initiated. Beyond this range, equalization stops. In the uninterrupted equalization phase, the polarization effect is not suppressed, and the voltage difference between this cell and other cells 5 continues to widen. After charging and discharging, during the resting phase, the accumulated voltage deviation becomes more pronounced, making the voltage of this cell 5 significantly higher than that of other cells 5. After multiple charge / discharge cycles, the voltage difference is continuously amplified. When the final voltage difference exceeds a set value (e.g., 200mV), it is determined that the polarization resistance of cell 5 deviates from the average value by more than the preset threshold, and it is identified as an outlier cell, triggering an alarm.

[0030] During the charging and discharging process of the battery pack, cell 5, with its low polarization resistance, exhibits a weaker polarization effect when the same current is applied, resulting in a slow voltage rise that is significantly lower than the average voltage of cell 5. Within the preset charging and discharging range, the battery management system detects that its voltage difference has reached the equalization activation threshold, designates it as a target cell, and equalizes it during the charging process. Once the preset charging and discharging range is exceeded, equalization stops, and without equalization adjustment, the voltage difference between cell 5 and other cells 5 gradually widens. After the charging and discharging cycle, the voltage deviation accumulated during the resting phase becomes prominent, with cell 5's voltage significantly lower than other cells 5. After multiple charging and discharging cycles, the voltage difference continues to amplify. When the terminal voltage difference meets the outlier detection criteria and the polarization resistance deviates from the average value exceeding the set standard, it is identified as an outlier cell and an alarm signal is issued.

[0031] like Figure 2 and Figure 3 As shown, Figure 2 and Figure 3 This graph shows the voltage change of cell 5 over time during two charge-discharge cycles. Blue represents the maximum voltage of cell 5, orange represents the minimum voltage, gray represents the average voltage, and yellow represents the voltage of outlier cells. Equalization is performed during charging and discharging. After the charge-discharge cycle, the voltage difference of cell 5 becomes prominent, allowing for the screening of outlier cells with abnormal polarization resistance.

[0032] In some embodiments, by employing a strategy of balancing only within a preset charge / discharge range and stopping balancing outside of that range, the voltage deviation caused by the difference in polarization internal resistance is specifically amplified. This allows for the precise location of outlier cells with large differences in polarization internal resistance, reducing issues such as reduced usable battery pack capacity and frequent triggering of the balancing system caused by cell inconsistency. It also reduces the risk of thermal runaway caused by thermal imbalance, while reducing ineffective energy consumption during balancing and component wear. This improves the control accuracy of the battery management system and extends the lifecycle performance and reliability of lithium battery energy storage systems and electric vehicle battery packs.

[0033] Reference Figure 4 In some embodiments, outlier cells with polarization internal resistance outliers are determined based on the voltage of each cell 5, including: S301. Determine the range and the first absolute deviation of each cell 5 based on the voltage of each cell 5; It is understandable that the range refers to the difference between the maximum and minimum values ​​of the voltage of all cells 5, and the first absolute deviation refers to the absolute value of the difference between the voltage of a single cell 5 and the average voltage of all cells 5.

[0034] S302. When the range is greater than the first threshold, the cell 5 with the first absolute deviation greater than the second threshold is regarded as an outlier cell.

[0035] Understandably, outlier cells are identified through dual voltage parameters, and cells with abnormal polarization resistance are precisely screened through multi-dimensional voltage analysis. The first threshold is a critical value used to determine the overall degree of voltage dispersion, with a common range of 100mV-300mV, such as 100mV, 150mV, 200mV, 250mV, 300mV, etc.; the second threshold is a critical value used to determine whether the voltage of a single cell deviates from the average level, with a common range of 75mV-100mV, such as 75mV, 80mV, 90mV, 100mV, etc.

[0036] After completing the charge-discharge cycle, the battery management system first calculates the average voltage of all cells 5, and then calculates the first absolute deviation of the voltage of each cell 5 and the range of the voltage of all cells 5. When the calculated range is greater than the first threshold and the first absolute deviation of cell 5 is greater than the second threshold, the system identifies the cell 5 with the first absolute deviation exceeding the standard as an outlier cell.

[0037] In some embodiments, the overall voltage dispersion of all cells 5 is determined by the range, which can quickly identify scenarios with extremely poor overall consistency; the deviation of a single cell 5 from the average voltage is determined by the first absolute deviation, which can accurately pinpoint individual abnormal cells 5. The joint determination of dual parameters avoids the one-sidedness of a single indicator and effectively correlates the polarization internal resistance difference with voltage anomalies, thereby improving the accuracy and reliability of outlier cell identification.

[0038] In some embodiments, the first threshold is between 150mV and 200mV.

[0039] Understandably, the range of the first threshold is based on the voltage deviation characteristics caused by the difference in polarization internal resistance and the detection voltage range. The threshold between 150mV and 200mV can effectively identify significant overall voltage differences and avoid misjudgment due to small fluctuations. Possible specific values ​​include 150mV, 160mV, 180mV, 200mV, etc.

[0040] In some embodiments, the second threshold is between 75mV and 100mV.

[0041] Understandably, the second threshold is used to determine the degree of voltage deviation of a single cell 5. Based on the voltage deviation characteristics caused by the difference in polarization internal resistance and the detectable voltage range, the threshold between 75mV and 100mV is adapted to the deviation of the cell 5 with abnormal polarization internal resistance from the average voltage. This can accurately capture individual abnormalities while eliminating normal fluctuation interference. Possible specific values ​​include 75mV, 80mV, 90mV, 100mV, etc.

[0042] After calculating the voltage range of each cell 5, the range is compared with a set first threshold. Simultaneously, the first absolute deviation of the voltage of each cell 5 is calculated, and each first absolute deviation is compared with a set second threshold. When the range is greater than the set first threshold, and the first absolute deviation of cell 5 is greater than the set second threshold, cell 5 with the excessive first absolute deviation is identified as an outlier cell.

[0043] In some embodiments, by limiting the first threshold to between 150mV and 200mV, the overall voltage dispersion range caused by polarization resistance differences can be accurately matched, reducing missed detections due to excessively high thresholds or false detections due to excessively low thresholds. By limiting the second threshold to between 75mV and 100mV, the deviation of the abnormal polarization resistance cell 5 from the average voltage can be accurately captured, improving the accuracy of individual anomaly identification. The specific range setting of the dual thresholds makes the determination of outlier cells more targeted and reliable, fully adapting to the actual needs of polarization resistance diagnosis.

[0044] Reference Figure 5 In some embodiments, the target cell to be balanced is determined based on the voltage of a plurality of cells 5 electrically connected to the battery management system, including: S101. Determine the second absolute deviation of each cell 5 based on the voltage of the multiple cells 5 electrically connected to the battery management system. Understandably, the second absolute deviation refers to the absolute value of the difference between the voltage of a single cell 5 and the average voltage of all cells 5. It can be determined based on the polarization internal resistance and the charging and discharging current. For example, if the deviation of the polarization internal resistance is 100μΩ and the charging and discharging current is 100A, then the difference in polarization internal resistance will cause a voltage difference of 10mV.

[0045] S102, Select cell 5 with the second absolute deviation greater than the third threshold as the target cell.

[0046] Understandably, the step of selecting target cells based on the deviation of cell 5's voltage from the overall average level accurately identifies cells 5 with inconsistent voltages. The third threshold is the critical value for determining whether the voltage of cell 5 needs to be balanced, with a common range of 10mV to 20mV, such as 10mV, 15mV, 20mV, etc.

[0047] In some embodiments, the second absolute deviation directly reflects the degree of deviation of a single cell 5 from the overall average voltage, and the judgment logic is simple and intuitive; by reasonably setting the third threshold, it is possible to accurately distinguish between normal voltage fluctuations and voltage differences that need to be balanced, ensuring the targeting of the target cell selection, reducing invalid triggering of the balancing system, and reducing energy consumption and component losses.

[0048] In some embodiments, the third threshold is between 10mV and 20mV.

[0049] It is understandable that the requirement for voltage consistency of the 10mV to 20mV range for adapting the battery cells is necessary. This not only allows for timely identification of voltage differences that need to be balanced, but also avoids frequent triggering of balancing due to small fluctuations. This range can include 10mV, 12mV, 15mV, 18mV, 20mV, etc.

[0050] In some embodiments, by limiting the third threshold to between 10mV and 20mV, the voltage deviation caused by the difference in polarization internal resistance during the dynamic operation of the battery cell 5 can be accurately matched, preventing the accumulation of voltage inconsistencies due to an excessively high threshold, or the frequent triggering of the equalization system due to an excessively low threshold. This range setting not only ensures the voltage consistency of the battery cell 5, but also reduces the energy consumption and component losses caused by ineffective equalization, thereby improving the practicality and economy of the equalization strategy.

[0051] Reference Figure 6 In some embodiments, a second absolute deviation of each cell 5 is determined based on the voltage of a plurality of cells 5 electrically connected to the battery management system; cells 5 with a second absolute deviation greater than a third threshold are designated as target cells, including: S1011. Determine the average voltage and the second absolute deviation of each cell 5 based on the voltage of the multiple cells 5 electrically connected to the battery management system. Understandably, the average voltage is the average of the voltages of all cells, and the second absolute deviation is the absolute value of the difference between the voltage of a single cell and the average voltage.

[0052] S1012. Sort the cells 5 whose voltage is greater than the average voltage and whose second absolute deviation is greater than the third threshold in descending order, and determine the first N cells 5 as target cells, where N is a positive integer, such as 1, 2, 3, etc.

[0053] Equalizing the target cells within the preset charge / discharge range includes: equalizing the discharge of N target cells within the preset charge / discharge range.

[0054] Understandably, based on the case where cell 5's voltage is higher than the average voltage, target cells are selected and matched with corresponding equalization methods. Discharge equalization is then performed on these target cells. The third threshold is between 10mV and 20mV (e.g., 10mV, 15mV, 20mV, etc.), and the number of target cells can be determined according to the equalization channel capacity, such as 1, 2, 3, etc.

[0055] S1013. Sort the cells 5 whose voltage is less than the average voltage and whose second absolute deviation is greater than the third threshold in ascending order, and determine the first M cells 5 as target cells, where M is a positive integer, such as 1, 2, 3, etc. Equalizing the target cells within the preset charge / discharge range includes: equalizing the charge of M target cells within the preset charge / discharge range.

[0056] Understandably, based on the case where the voltage of cell 5 is lower than the average voltage, target cells are selected and matched with corresponding equalization methods. Charging equalization is then performed on these target cells. The second absolute deviation is the absolute value of the difference between the voltage of a single cell 5 and the average voltage of all cells 5. The third threshold is between 10mV and 20mV (e.g., 10mV, 15mV, 20mV, etc.). The number of at least one cell 5 with the lowest voltage can be determined according to the equalization channel capacity, such as 1, 2, 3, etc.

[0057] After the battery management system calculates the average voltage of all cells 5 and the second absolute deviation of each cell 5, when the voltage of a cell 5 is greater than the average voltage and the second absolute deviation is greater than the third threshold, the cell 5 voltages are sorted from largest to smallest, and N cells 5 with larger voltages are selected as target cells for discharge equalization. When the voltage of a cell 5 is less than the average voltage and the second absolute deviation is greater than the third threshold, the cell 5 voltages are sorted from smallest to largest, and M cells 5 with smaller voltages are selected as target cells for charging equalization.

[0058] In some embodiments, by screening target cells at the high-voltage end and performing discharge equalization, high-voltage deviations can be precisely reduced, preventing such cells 5 from reaching the charging cutoff voltage prematurely; by screening target cells at the low-voltage end and performing charging equalization, low-voltage deviations can be precisely compensated, preventing such cells 5 from reaching the discharge cutoff voltage prematurely. Bidirectional precise adjustment not only ensures the voltage consistency of cells 5, but also reduces the ineffective loss of equalization.

[0059] Reference Figure 7 and Figure 8 In some embodiments, the battery management system includes a slave controller 1 (VCMU), a master controller 2 (SBMU), a human-machine interface 3 (HMI), and multiple battery modules 4. Each battery module 4 includes multiple battery cells 5. The slave controller 1 is used for acquiring the voltage and temperature of the battery cells 5, supports active balancing, and can detect 24 to 128 cells in series. The slave controller 1 integrates a high-frequency sampling circuit, supporting μΩ-level polarization resistance voltage detection during charging and discharging. The master controller 2 receives cell data reported by the slave controller 1 via a communication cable 6, performs overall system cell balancing control, identifies abnormal cells, and issues alarms. It can receive information from 128 slave controllers. The master controller 2 has a built-in outlier analysis algorithm to identify the voltage trajectory of abnormal cells in real time. The human-machine interface 3 displays the voltage, temperature, and alarm information of the battery cells 5; it also visualizes a three-dimensional thermal map of the polarization resistance and supports fault tracing map generation. Communication cable 6 adopts a star communication topology (CAN FD bus) to achieve a data synchronization delay of <10ms for 128 nodes; it is equipped with a multi-level isolated power supply module to ensure a sampling accuracy of ±0.05% under 0.5C current.

[0060] Reference Figure 7 and Figure 8 In some embodiments, the battery management system employs a non-dissipative balancing design. This design uses a balancing controller to control the drive circuit of the MOSFET switch, transferring energy via DC-DC converters, and using a multiplexer to enable the DC-DC converters to conduct to each cell 5 within the battery module 4, thus facilitating energy transfer between cells 5. Each AFE manages a maximum of 16 cells 5, and each AFE corresponds to one balancing channel. Each slave board has two AFEs, i.e., two balancing channels. Each balancing channel can only simultaneously activate one cell 5 for either charging or discharging balancing.

[0061] In some embodiments, 0 < M*Pch - N*Pdc < P0, M + N < Z, where M and N are positive integers, Pch is the power consumption for equalizing charging in a single channel, Pdc is the power release for equalizing discharging in a single channel, P0 is the external input power, and Z is the total number of equalization channels in the battery management system.

[0062] Understandably, by quantitatively constraining the number of target cells, balancing power, and number of channels for discharge balancing and charge balancing, precise matching of balancing power and capacity is achieved, ensuring efficient and safe balancing. The target number of cells for discharge balancing is N, and the target number of cells for charge balancing is M, where M and N are both positive integers. The constraints are 0 < MPch - NPdc < P0 and M + N < Z, ensuring that the difference in balancing power is within a reasonable range and does not occupy all balancing channels.

[0063] In some embodiments, the constraint 0 < MPch - NPdc < P0 allows for precise control of the power difference during the equalization process, preventing insufficient equalization power or excessive consumption of external power, ensuring both equalization efficiency and safety. The constraint M + N < Z reserves sufficient redundancy for equalization channels, preventing channel overload and thus improving the stability of the equalization process. This quantitative constraint allows for a more scientific matching of the target cell quantity, balancing equalization effectiveness and system safety, further optimizing the practicality and reliability of the equalization strategy.

[0064] Reference Figure 9 In some embodiments, the cell 5 with a second absolute deviation greater than a third threshold is selected as the target cell, including: S1014. When the voltage of cell 5 is in the first preset range, cell 5 with a second absolute deviation greater than the third threshold is selected as the target cell.

[0065] Balancing the target cell within the preset charge / discharge range includes: balancing the discharge of the target cell within the preset charge / discharge range.

[0066] Understandably, a voltage range limit is added to the target cell for discharge equalization to adapt to the discharge equalization voltage reduction requirements. The range can be 3.0V~3.7V, 3.1V~3.6V, 3.3V~3.5V, etc., to ensure that cell 5 performs discharge equalization within a safe high voltage range and reduce the risk of over-discharge.

[0067] S1015. When the voltage of cell 5 is in the second preset range, cell 5 with a second absolute deviation greater than the third threshold is taken as the target cell.

[0068] Balancing the target cell within the preset charge / discharge range includes: balancing the charge of the target cell within the preset charge / discharge range.

[0069] Understandably, voltage range limits are added to the target cells for charging balancing to adapt to the charging balancing boost requirements. The ranges are 2.5V~3.4V, 2.6V~3.3V, 2.7V~3.2V, etc., to ensure that cell 5 performs charging balancing within a safe low voltage range and reduce the risk of overcharging.

[0070] In some embodiments, limiting the voltage range by the first preset range can reduce over-discharge faults caused by high-voltage cell 5 discharge, ensuring the safety of discharge equalization; limiting the voltage range by the second preset range can reduce the risk of overcharging caused by low-voltage cell 5 charging, ensuring the safety of charging equalization. The voltage range constraint combined with deviation screening ensures both the targeting of equalization and the safety of cell 5 equalization, allowing the equalization process to improve both the consistency and safety stability of cell 5.

[0071] In some embodiments, the first preset range is between 3.0V and 3.7V.

[0072] Understandably, the first preset range is between 3.0V and 3.7V, which is suitable for the safe discharge requirements of cell 5. Selectable ranges include 3.0V to 3.7V, 3.1V to 3.6V, 3.3V to 3.5V, etc., or fixed voltage nodes within the range can be selected as the judgment boundary, such as 3.0V, 3.1V, 3.3V, 3.5V, 3.6V, 3.7V, etc.

[0073] In some embodiments, the second preset range is between 2.5V and 3.4V.

[0074] Understandably, the second preset range is between 2.5V and 3.4V, which is suitable for the safe charging requirements of battery cell 5. Selectable ranges include 2.5V to 3.4V, 2.6V to 3.3V, and 2.7V to 3.2V. Alternatively, a fixed voltage node within the range can be selected as the judgment boundary, such as 2.5V, 2.6V, 2.9V, 3.0V, 3.3V, and 3.4V.

[0075] When determining the target cell that needs to be discharged and balanced, the voltage of cell 5 is simultaneously checked to see if it is in the first preset range of 3.0V to 3.7V. If it is in this range, discharge balancing is performed. When determining the target cell that needs to be charged and balanced, the voltage of cell 5 is simultaneously checked to see if it is in the second preset range of 2.5V to 3.4V. If it is in this range, charge balancing is performed.

[0076] In some embodiments, limiting the voltage range to between 3.0V and 3.7V by the first preset range can reduce the risk of over-discharge caused by the discharge of high-voltage cell 5, ensuring the safety of discharge equalization; limiting the voltage range to between 2.5V and 3.4V by the second preset range can reduce the risk of overcharge caused by the charging of low-voltage cell 5, ensuring the safety of charging equalization. Precise voltage range limitation combined with deviation screening ensures both targeted equalization and the safety of cell 5 equalization, allowing the equalization process to balance consistency improvement and safety stability.

[0077] Reference Figure 10 In some embodiments, equalization of the target cell is performed within a preset charge / discharge range, including: S201. When the SOC is charged to the range of 5%-95%, the target cell is balanced.

[0078] Understandably, the SOC is within a balanced range of 5%-95%, which can be flexibly adjusted according to the charging rate, battery type (such as ternary lithium battery, lithium iron phosphate battery) and application scenario. Possible ranges include 5%-95%, 10%-90%, 15%-85%, 20%-80%, 30%-70%, etc.

[0079] S202. When the SOC is discharged to the range of 5%-95%, the target cell is balanced.

[0080] Understandably, the SOC is within a balanced range of 5%-95%, which can be flexibly adjusted according to the discharge rate, battery type (such as ternary lithium battery, lithium iron phosphate battery) and application scenario. Possible ranges include 5%-95%, 10%-90%, 15%-85%, 20%-80%, 30%-70%, etc.

[0081] When the battery pack is charging and the battery management system detects that the State of Charge (SOC) is between 5% and 95%, the system activates the balancing mechanism to discharge or charge target cells with voltages higher or lower than the average voltage. Similarly, when the battery pack is discharging and the SOC is between 5% and 95%, the battery management system continuously monitors the voltage of each cell, and the system activates the balancing mechanism to discharge or charge target cells with voltages higher or lower than the average voltage.

[0082] In some embodiments, balancing the charging phase within the SOC range of 5%-95% can effectively suppress charging voltage deviations caused by differences in polarization resistance, thus preventing overcharging or undercharging of the target cell. Similarly, balancing the discharging phase within the SOC range of 5%-95% can mitigate the accumulation of voltage deviations caused by polarization resistance during discharging, preventing premature termination of discharge by the target cell and ensuring the consistency and stability of the battery pack throughout the entire charging and discharging process.

[0083] By balancing the target cells within the SOC range of 5%-95% during the charge and discharge phases, the charging voltage deviation caused by differences in polarization resistance is corrected in real time. This ensures that the voltage of cell 5 tends to be consistent during the balancing process, preventing individual cells 5 from being overcharged or undercharged, and maintaining the voltage balance of cell 5. Balancing stops once the preset charge and discharge range is exceeded, allowing the differences in polarization resistance to naturally amplify without interference. This makes the voltage difference between cell 5 stand out after the charge and discharge cycle is completed, which can accurately identify outlier cells with abnormal polarization resistance, improve the efficiency of cell 5 consistency diagnosis, and extend the service life of the battery pack.

[0084] In some embodiments, the method further includes: performing charge-discharge cycles on a plurality of cells 5, wherein, in each charge-discharge cycle, a target cell to be balanced is determined based on the voltage of the plurality of cells 5 electrically connected to the battery management system; the target cell is balanced within a preset charge-discharge interval, and the balancing of the target cell is stopped outside the preset charge-discharge interval while the charge-discharge cycle continues; and outlier cells with polarization internal resistance outliers are determined based on the voltage of each cell 5.

[0085] It is understandable that a charge-discharge cycle refers to completing one cycle by charging to full capacity with constant current, resting for a preset time, discharging to depletion with constant current, and then resting for another preset time. Simultaneously, a preset charge-discharge interval is used for balancing during the cycle, while balancing is stopped in other intervals. After balancing stops, charging or discharging continues. Differences in polarization internal resistance will cause voltage differences in cell 5. After iterating through this cycle multiple times, the voltage deviation of cell 5 with abnormal polarization internal resistance will gradually accumulate and amplify. It should be noted that the cycle can be repeated 1, 2, 3 times, etc., depending on the magnitude of the polarization internal resistance deviation to be monitored. When monitoring a large polarization internal resistance deviation, the number of cycles can be appropriately reduced; when monitoring a small polarization internal resistance deviation, the number of cycles can be appropriately increased.

[0086] Reference Figure 11 In some embodiments, the charge-discharge cycle includes a charging phase and a discharging phase.

[0087] In some examples, the device is left to stand still for a first preset duration after the charging phase.

[0088] Understandably, a resting period is set after each charge-discharge cycle to eliminate the dynamic polarization effect generated during charging, ensuring that the monitored target cell voltage is closer to its true equilibrium potential. The first preset duration needs to be set according to factors such as battery type and charging rate, with the aim of stabilizing the cell voltage to a static level. A common range is 10 minutes to 120 minutes, such as 10 minutes, 30 minutes, 60 minutes, 90 minutes, and 120 minutes.

[0089] In some examples, a second preset duration of rest is performed after the discharge phase.

[0090] Understandably, a resting period is set after the discharge process of each charge-discharge cycle to eliminate the dynamic polarization effect generated during discharge, ensuring that the monitored target cell voltage is closer to its true equilibrium potential. The second preset duration needs to be set according to factors such as battery type and discharge rate, with the aim of stabilizing the cell voltage to a static level. Common ranges are 10 minutes to 120 minutes, such as 10 minutes, 30 minutes, 60 minutes, 90 minutes, and 120 minutes.

[0091] In each charge-discharge cycle, after the battery pack completes the charging operation, the battery management system controls the battery pack to enter a resting state and starts timing. When the first preset time is reached, the voltage data of each target cell is collected and stored. In each charge-discharge cycle, after the battery pack completes the discharging operation, the battery management system controls the battery pack to enter a resting state and starts timing. When the second preset time is reached, the voltage data of each target cell is collected and stored.

[0092] In some embodiments, during the battery charging and discharging process, the resting time (a buffer phase without current) is a key factor in ensuring its performance, safety, and lifespan: resting before charging can balance the voltage and SOC of multiple cells, avoiding local overcharging in the early stages of charging; resting during charging intervals can alleviate electrochemical and concentration polarization, improve charging efficiency, and prevent overheating; resting after charging allows lithium ions to fully embed into the electrodes, eliminating dummy charges; resting during discharging intervals can reduce discharge polarization, avoiding voltage drops and high temperatures; and resting after discharging can terminate residual reactions and prevent deep over-discharge from damaging the electrodes.

[0093] Reference Figure 12 In some embodiments, the target cell is balanced within a preset charge-discharge range, including: S203, performing multiple balances on the target cell within the preset charge-discharge range.

[0094] Understandably, within the preset charge / discharge range, real-time balancing is performed to keep the voltage of the target cell consistent with the voltage of other cells 5.

[0095] S2031. Obtain the voltage V1 of cell 5 before equalization.

[0096] Understandably, the original voltage value of each cell 5 is collected before equalization and recorded as V1.

[0097] S2032. Perform the first equalization in the preset charge and discharge range to obtain the voltage V2 of cell 5.

[0098] Understandably, after the first equalization is completed, the real-time voltage value of each cell is collected and recorded as V2.

[0099] S2033, Obtain the compensation voltage value based on V1 and V2. V.

[0100] It is understandable that the compensation voltage value is calculated by subtracting V2 from V1. V, V can be positive or negative.

[0101] S2034. Within the preset charge / discharge range, use the compensation voltage value V compensates for the voltage of cell 5 and performs multiple equalization operations.

[0102] It is understandable that by compensating for voltage values ​​to optimize balancing accuracy, a charging and discharging process involves multiple balancing operations, and each subsequent balancing operation relies on this difference. V compensates and calibrates the voltage of cell 5, thereby calibrating the equalization adjustment amplitude to make the equalization adjustment more in line with the actual characteristics of cell 5.

[0103] In some embodiments, the compensation voltage value is obtained by calculating V1 minus V2. V can accurately capture the actual adjustment effect of a single equalization, providing a precise reference for subsequent equalizations; the difference is then used in subsequent equalizations. V-compensation of cell 5 voltage can improve the adjustment accuracy of multi-cycle balancing and reduce the voltage deviation between cells 5. Precise compensation combined with multi-cycle balancing ensures both the stability of balancing and improves the voltage consistency of cells 5.

[0104] Reference Figure 13 In some embodiments, equalization of the target cell is performed within a preset charge / discharge range, including: S204. When the battery management system is under the preset equalization start-up conditions, the target cell is equalized in the preset charge and discharge range. The preset equalization start-up conditions include normal cell voltage detection, normal temperature detection, normal current detection, normal equalization current, normal DC-DC converter, normal slave control power supply voltage, normal equalization over-temperature, battery temperature greater than or equal to the preset temperature, normal communication, and normal grounding.

[0105] Understandably, the following conditions must be met simultaneously: normal voltage detection, normal temperature detection, normal current detection, normal balancing current, normal DC-DC converter, normal slave control power supply voltage, normal balancing over-temperature, battery temperature greater than or equal to the preset temperature, normal communication, and normal grounding. Then, the main controller 2 sends a balancing command to balance the target cell within the preset charge and discharge range. All conditions must be met simultaneously to ensure safe and reliable balancing startup.

[0106] Reference Figure 14 In some embodiments, equalization of the target cell is performed within a preset charge / discharge range, including: S205. When the battery management system is under the preset equalization shutdown condition, stop equalizing the target cell. The preset equalization shutdown condition includes at least one of the following: cell 5 voltage detection fault, temperature detection fault, current detection fault, equalization overcurrent fault, DC-DC fault, slave control power supply overvoltage fault, slave control power supply undervoltage fault, equalization overtemperature fault, battery temperature is lower than the preset temperature, communication fault, and grounding fault.

[0107] It is understandable that the main controller 2 triggers the equalization shutdown condition including at least one of the following: cell 5 voltage detection failure, temperature detection failure, current detection failure, equalization overcurrent failure, DC-DC failure, slave control power supply overvoltage failure, slave control power supply undervoltage failure, equalization overtemperature failure, battery temperature lower than preset temperature, communication failure, and grounding failure. When any condition is triggered, the main controller 2 sends an equalization shutdown command to stop equalizing the target cell.

[0108] It is understandable that the conditions for the slave controller 1 to autonomously trigger the balancing shutdown include at least one of the following: balancing overcurrent fault, DC-DC fault, balancing overtemperature fault, and slave control power supply undervoltage fault. When any condition is triggered, the slave controller 1 does not need to wait for the master controller 2's instruction and directly shuts down the balancing process within the current balancing cycle, stops responding to the master controller 2's balancing command, and stops balancing the target cell.

[0109] In some embodiments, limiting the balancing start-up under multiple normal conditions reduces the risk of balancing start-up under fault conditions and ensures the safety of the initial balancing state; triggering the main controller 2 to shut down balancing under abnormal conditions by multiple types of fault conditions can promptly terminate balancing under abnormal conditions and reduce cell 5 losses; triggering the slave controller 1 to autonomously shut down balancing under fault conditions can quickly respond to emergency faults and improve the balancing safety protection level. The hierarchical setting of balancing start-up and shutdown conditions ensures both the safety of balancing start-up and the timeliness of balancing shutdown, ensuring that the balancing process fully complies with safety specifications and takes into account both cell 5 consistency and operational safety.

[0110] Reference Figure 15 In some embodiments, equalization of the target cell is performed within a preset charge / discharge range, including: S203. Perform multiple equalizations on the target cell within the preset charge / discharge range; S2035. Each equalization lasts for a third preset duration, and equalization stops for a fourth preset duration after equalization. Jump to S1. Based on the voltage of the multiple cells 5 electrically connected to the battery management system, determine the target cell to be balanced.

[0111] Understandably, the balancing process is intermittent. During balancing, it first runs continuously for a third preset duration, then stops for a fourth preset duration. After the interval, the target cell to be balanced is re-evaluated to adapt to the dynamic voltage changes of the cell, reducing losses caused by continuous balancing. It also reduces the operating time of the balancing devices, increasing their lifespan and preventing overheating. The third preset duration is the duration of a single balancing cycle, ranging from 50s to 60s (e.g., 50s, 55s, 60s). The fourth preset duration is the balancing stop interval, ranging from 5s to 10s (e.g., 5s, 8s, 10s). It should be noted that the third and fourth preset durations can constitute one balancing cycle. That is, within one cycle, such as 60s, when the third preset duration is 50s, the fourth preset duration is 10s; when the third preset duration is 55s, the fourth preset duration is 5s.

[0112] In some embodiments, intermittent equalization combined with re-judgment of the target cell ensures both the equalization adjustment effect and the equalization energy consumption, making the equalization process conform to the actual state of the cell 5 and improving the voltage consistency regulation efficiency.

[0113] According to the second aspect of this disclosure, referring to Figure 16 A balancing device is provided, applicable to the aforementioned balancing method. The device includes a sampling module 410, a balancing module 420, and a screening module 430. The sampling module 410 determines the target cell to be balanced based on the voltages of multiple cells 5 electrically connected to the battery management system. The balancing module 420 balances the target cell within a preset charge-discharge range. The screening module 430 stops balancing the target cell outside the preset charge-discharge range of the charge-discharge cycle and identifies outlier cells with polarization internal resistance outliers based on the voltage of each cell 5.

[0114] The balancing device in this application embodiment is applied to an energy storage system, which includes a battery pack.

[0115] According to embodiments of this application, any multiple modules among the sampling module 410, the equalization module 420, and the filtering module 430 can be combined into one module, or any one of the modules can be split into multiple modules.

[0116] Alternatively, at least some of the functionality of one or more of these modules can be combined with at least some of the functionality of other modules and implemented in a single module.

[0117] According to embodiments of this application, at least one of the sampling module 410, the equalization module 420, and the filtering module 430 can be at least partially implemented as hardware circuitry, such as a field-programmable gate array (FPGA), a programmable logic array (PLA), a system-on-a-chip, a system-on-a-substrate, a system-on-package, an application-specific integrated circuit (ASIC), or any other reasonable means of integrating or packaging the circuitry, or implemented in any one of the three methods of software, hardware, and firmware, or in a suitable combination of any of these.

[0118] Alternatively, at least one of the sampling module 410, the equalization module 420, and the filtering module 430 may be implemented at least partially as a computer program module, which can perform corresponding functions when the computer program module is run.

[0119] It should be noted that the equalization device provided in this application embodiment can implement all the method steps implemented in the above equalization method embodiment and can achieve the same technical effect. Here, the parts that are the same as those in the method embodiment and the beneficial effects will not be described in detail.

[0120] According to the third aspect of this disclosure, referring to Figure 17 An electronic device is provided, which may include: a processor 510, a communication interface 520, a memory 530, and a communication bus 540, wherein the processor 510, the communication interface 520, and the memory 530 communicate with each other through the communication bus 540. The processor 510 can call a computer program in the memory 530 to execute the above-described method, which includes, for example: determining a target cell to be balanced based on the voltage of a plurality of cells 5 electrically connected to a battery management system; balancing the target cell within a preset charge-discharge interval; stopping the balancing of the target cell outside the preset charge-discharge interval of the charge-discharge cycle; and determining outlier cells with polarization internal resistance outliers based on the voltage of each cell 5.

[0121] Furthermore, the logical instructions in the aforementioned memory 530 can be implemented as software functional modules and sold or used as independent products, and can 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 the prior art, or part of the technical solution, 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 steps of the methods of 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), random access memory (RAM), magnetic disks, or optical disks.

[0122] It should be noted that the electronic device provided in this application embodiment can implement all the method steps implemented in the above-mentioned equalization method embodiment and can achieve the same technical effect. Here, the parts that are the same as those in the method embodiment and the beneficial effects will not be described in detail.

[0123] According to a fourth aspect of this disclosure, embodiments of this application also provide a storage medium storing a computer program for causing a processor 510 to execute the methods provided in the above embodiments.

[0124] The storage medium can be any available medium or data storage device that the processor 510 can access, including but not limited to magnetic storage (e.g., floppy disk, hard disk, magnetic tape, magneto-optical disk (MO)), optical storage (e.g., CD, DVD, BD, HVD), and semiconductor storage (e.g., ROM, EPROM, EEPROM, non-volatile memory (NAND FLASH), solid-state drive (SSD)).

[0125] It should be noted that the storage medium provided in this application embodiment can implement all the method steps implemented in the above-mentioned equalization method embodiment and can achieve the same technical effect. Here, the parts that are the same as those in the method embodiment and the beneficial effects will not be described in detail.

[0126] According to the fifth aspect of this disclosure, embodiments of this application also provide a computer program product, which includes a computer program that can be stored on a storage medium. When the computer program is executed by a processor 510, the computer is able to perform the methods provided in the above embodiments.

[0127] It should be noted that the computer program product provided in this application embodiment can implement all the method steps implemented in the above-mentioned equilibrium method embodiment and can achieve the same technical effect. Here, the parts that are the same as those in the method embodiment and the beneficial effects will not be described in detail.

[0128] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0129] The device embodiments described above are merely illustrative. The modules described as separate components may or may not be physically separate, and the components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0130] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0131] The embodiments of this application have been described in detail above. Specific examples have been used in this application to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An equilibrium method, characterized in that, include: The target cell to be balanced is determined based on the voltage of the multiple cells (5) electrically connected to the battery management system. Charge and discharge multiple battery cells (5), and balance the target battery cell within a preset charge and discharge range. Stop balancing the target battery cell outside the preset charge and discharge range and continue charging and discharging. The outlier cells with polarization internal resistance outliers are determined based on the voltage of each of the cells (5).

2. The equalization method according to claim 1, characterized in that, The outlier cells with polarization internal resistance outliers are determined based on the voltage of each of the cells (5), including: The range and the first absolute deviation of each of the cells (5) are determined based on the voltage of each cell (5); When the range is greater than the first threshold, the cell (5) with the first absolute deviation greater than the second threshold is regarded as the outlier cell.

3. The balancing method according to claim 2, characterized in that, The first threshold is between 150mV and 200mV; and / or, The second threshold is between 75mV and 100mV.

4. The balancing method according to any one of claims 1-3, characterized in that, Based on the voltages of the plurality of cells (5) electrically connected to the battery management system, the target cell to be balanced is determined, including: The second absolute deviation of each of the multiple cells (5) electrically connected to the battery management system is determined based on the voltage of each cell (5); The cell (5) whose second absolute deviation is greater than the third threshold is taken as the target cell.

5. The equalization method according to claim 4, characterized in that, The third threshold is between 10mV and 20mV.

6. The equalization method according to claim 4, characterized in that, The second absolute deviation of each of the multiple cells (5) electrically connected to the battery management system is determined based on the voltage of each cell (5); The cell (5) whose second absolute deviation is greater than the third threshold is taken as the target cell, including: The average voltage and the second absolute deviation of each of the multiple cells (5) electrically connected to the battery management system are determined based on the voltage of the cells (5). The cells (5) whose voltage is greater than the average voltage and whose second absolute deviation is greater than the third threshold are sorted from largest to smallest, and the first N cells (5) are determined as the target cells. Equalization of the target battery cell within a preset charge / discharge range; including: Discharge equalization is performed on N target cells within a preset charge / discharge range; And / or, The cells (5) whose voltage is less than the average voltage and whose second absolute deviation is greater than the third threshold are sorted in ascending order, and the first M cells (5) are determined as the target cells. Equalization of the target battery cell within a preset charge / discharge range; including: The target cells are charged and balanced within a preset charge / discharge range; Where M and N are positive integers.

7. The balancing method according to claim 6, characterized in that, 0 < M*Pch - N*Pdc < P0, M+N<Z, Where Pch is the power consumption for equalizing charging in a single channel, Pdc is the power release for equalizing discharging in a single channel, P0 is the external input power, and Z is the total number of equalization channels in the battery management system.

8. The balancing method according to claim 4, characterized in that, The cell (5) whose second absolute deviation is greater than the third threshold is taken as the target cell, including: When the voltage of the battery cell (5) is in the first preset range, the battery cell (5) with the second absolute deviation greater than the third threshold is taken as the target battery cell; Equalization of the target battery cell within a preset charge / discharge range; including: The target battery cell is discharged and balanced within a preset charge / discharge range; And / or, When the voltage of the battery cell (5) is in the second preset range, the battery cell (5) with the second absolute deviation greater than the third threshold is taken as the target battery cell; Equalization of the target battery cell within a preset charge / discharge range; including: The target battery cell is charged and balanced within a preset charge and discharge range.

9. The equalization method according to claim 8, characterized in that, The first preset range is between 3.0V and 3.7V; and / or, The second preset range is between 2.5V and 3.4V.

10. The balancing method according to any one of claims 1-9, characterized in that, Equalizing the target battery cell within a preset charge / discharge range includes: When the target battery cell is charged to a SOC between 5% and 95%, it is balanced; and / or, When the SOC is discharged to the range of 5%-95%, the target cell is balanced.

11. The balancing method according to any one of claims 1-10, characterized in that, The method further includes: The multiple cells are subjected to charge-discharge cycles, wherein, in each charge-discharge cycle, the target cell to be balanced is determined according to the voltage of the multiple cells (5) electrically connected to the battery management system; the target cell is balanced within a preset charge-discharge interval, and the balancing of the target cell is stopped outside the preset charge-discharge interval while the charge-discharge cycle continues; and the outlier cells with polarization internal resistance outliers are determined according to the voltage of each cell (5).

12. The balancing method according to any one of claims 1-11, characterized in that, Equalizing the target battery cell within the preset charge / discharge range includes: Obtain the voltage V1 of the cell (5) before equalization; The first equalization is performed in the preset charging and discharging range to obtain the voltage V2 of the cell (5) after the first equalization; The compensation voltage value is obtained based on V1 and V2. V; In the preset charge / discharge range, a compensation voltage value is used. V compensates for the voltage of the battery cell (5) and performs multiple equalizations.

13. The balancing method according to any one of claims 1-12, characterized in that, Equalizing the target battery cell within the preset charge / discharge range includes: When the battery management system is under preset equalization start-up conditions, the target cell is equalized within the preset charge / discharge range. The preset equalization start-up conditions include: normal cell (5) voltage detection, normal temperature detection, normal current detection, normal equalization current, normal DC-DC converter, normal slave control power supply voltage, normal equalization over-temperature, battery temperature greater than or equal to the preset temperature, normal communication, and normal grounding; and / or, When the battery management system is under the preset equalization shutdown condition, the equalization of the target cell is stopped. The preset equalization shutdown condition includes at least one of the following: cell (5) voltage detection fault, temperature detection fault, current detection fault, equalization overcurrent fault, DC-DC fault, slave-controlled power supply overvoltage fault, slave-controlled power supply undervoltage fault, equalization overtemperature fault, battery temperature is lower than the preset temperature, communication fault and grounding fault.

14. The balancing method according to any one of claims 1-13, characterized in that, Equalizing the target battery cell within the preset charge / discharge range includes: The target battery cell is balanced multiple times within the preset charging and discharging range; each balancing lasts for a third preset duration, and balancing stops for a fourth preset duration after balancing. The target cell to be balanced is determined based on the voltage of multiple cells (5) electrically connected to the battery management system.

15. An equalization device, characterized in that, The equalization method applicable to any one of claims 1-14, the equalization device comprising: The sampling module (410) is used to determine the target cell to be balanced based on the voltage of multiple cells (5) electrically connected to the battery management system. The equalization module (420) is used to charge and discharge multiple battery cells (5), and to equalize the target battery cell in a preset charge and discharge range, and to stop equalizing the target battery cell outside the preset charge and discharge range and continue charging and discharging. The screening module (430) is used to determine outlier cells with polarization internal resistance outliers based on the voltage of each of the cells (5).

16. An electronic device comprising a memory (530) and a processor (510), characterized in that, The memory (530) stores a computer program, and the processor (510) is configured to execute the method described in any one of claims 1 to 14 through the computer program.

17. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1 to 14.

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