A battery rotationally equalization method, device and medium

Abstract

The present application relates to the technical field of battery, particularly relates to a battery turn-by-turn equalization method, device and medium.The method comprises the following steps: arranging battery monomers according to voltage from high to low;discharging the battery monomers in the preset ranking according to the preset equalization electric quantity; updating the voltage sequence, and repeating the discharging of the battery monomers in the preset ranking according to the preset equalization electric quantity until all the battery monomers are discharged by equalization.The core of the present application is to make all the monomers reach the state of SOC sequence in the front by turn and adaptive step length.By capturing the monomer voltage in a specific state, the equalization of the monomers with the front ranking of the trigger voltage is adaptive each time, and the high SOC consistency between the battery monomers is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a battery alternating balancing method, apparatus and medium. Background Technology

[0002] Lithium-ion battery packs are the core power source of electric vehicles (EVs) and also represent a significant portion of their manufacturing cost. To improve output voltage and usable capacity, battery packs are typically constructed using hundreds of cells connected in series. During operation, this series structure ensures that all cells share the same operating current, i.e., they charge and discharge synchronously. However, when the actual usable charge (SOC) of a particular cell is significantly lower than that of the others, that cell will reach its cutoff voltage first during the discharge phase, rendering the energy in the remaining cells ineffective. Conversely, during the charging phase, if a cell reaches its full charge voltage ahead of others, the entire battery pack will stop charging, leaving some cells partially charged and impacting the overall usable energy. Therefore, the Battery Management System (BMS) needs to ensure that all cells within the battery pack have the same usable charge and that they simultaneously reach full discharge or full charge states; this function is commonly referred to as cell balancing.

[0003] Inconsistencies exist throughout the entire lifecycle of battery cells. During the manufacturing and assembly of cells, variations in processes can lead to inherent inconsistencies in capacity, internal resistance, and self-discharge rate before packaging. Furthermore, individual battery cells located in the automotive chassis area often experience uneven aging due to differences in heat dissipation caused by their topology and variations in temperature control by the thermal management system. In special cases, minor internal short circuits caused by loose connectors or impurities within the cell can exacerbate these inconsistencies.

[0004] Therefore, in automotive BMS, the cell balancing function needs to identify SOC differences in a timely and accurate manner through cell voltage. Only after identifying the differences can balancing be achieved through targeted discharge of specific cells. In recent years, due to the low cost and low thermal runaway risk of lithium iron phosphate (LFP) batteries, the market share of EVs using them as power batteries has increased rapidly. However, the open-circuit voltage-state-of-charge (OCV-SOC) curve of LFP batteries has a long plateau period; the open-circuit voltage value remains almost unchanged in the range of ~30% SOC to ~95% SOC. Figure 1As shown, this makes it extremely difficult to infer the battery's State of Charge (SOC) from the measured battery voltage. Furthermore, the measured terminal voltage is also affected by current polarization, especially concentration polarization and electrochemical polarization, which typically require hours to fully dissipate. The characteristics of polarization mean that algorithms for accurately inferring SOC from terminal voltage have stringent computational conditions: the cell's SOC must be in the non-plateau region at both ends, and an hour-long resting time must be ensured before measurement. Additionally, the BMS can correct the SOC when the cell reaches its full charge point; that is, if the cell reaches its full charge cutoff voltage within a specified current range, it is considered to have reached 100% SOC. As mentioned above, it is impossible for the numerous cells in a battery pack to reach their full charge cutoff voltage simultaneously. Therefore, for LFP batteries, the SOC difference between cells can be inferred from the significant voltage difference between cells still in the plateau region at full charge and those in the full charge region. However, this scheme, which requires the battery to be charged to 100% SOC, is also difficult to trigger. On the one hand, not all users regularly fully charge their batteries; on the other hand, some fast charging stations will stop charging prematurely when the cells are close to full charge. In summary, existing BMS equalization algorithms require accurate calculation of the SOC difference between cells, and the prerequisites for calculating SOC are quite stringent, making it difficult to trigger the equalization algorithm. Summary of the Invention

[0005] This invention discloses a battery alternating balancing method, device, and medium that can complete battery balancing without requiring precise cell SOC values.

[0006] To achieve the above objectives, a battery rotation balancing method is provided, the specific method of which is as follows:

[0007] Collect the voltage values ​​of individual battery cells and the current values ​​of the entire battery pack;

[0008] When the preset conditions are met, the individual battery cells are sorted from high to low voltage.

[0009] For individual cells with preset rankings, discharge them evenly according to preset equalization power.

[0010] Update the voltage sorting and repeatedly discharge the battery cells with the preset ranking according to the preset equalization charge until all battery cells have undergone equalization discharge.

[0011] Optionally, the preset conditions are for the high SOC segment. When the SOC is higher than the first threshold, the specific conditions are as follows:

[0012] Determine if the entire battery pack is in a charging state;

[0013] The difference between the highest and lowest voltages of individual cells within the battery pack is determined to be greater than the first voltage difference threshold.

[0014] Furthermore, when sorting individual battery cells from highest to lowest voltage, the method for obtaining the voltage of each individual cell is as follows:

[0015] Within a fixed time period, the voltage range between the highest and lowest voltages of a single cell is calculated multiple times to determine whether the voltage range increases sequentially.

[0016] If the voltage range increases sequentially, record the voltage values ​​of all individual cells in the latest fixed time period for sorting.

[0017] If the voltage range does not increase sequentially, the voltage values ​​of all individual cells in the last fixed time period when the voltage range decreases are recorded for sorting.

[0018] Optionally, the preset conditions apply to the SOC segment. When the SOC is lower than the first threshold and greater than the second threshold, the specific conditions are as follows:

[0019] Determine if the entire battery pack is in a charging state;

[0020] Within a first consecutive preset time period, it is determined that the difference between the highest and lowest voltages of individual cells in the battery pack is less than a second voltage difference threshold, and the current is less than a first current threshold within the preset time period.

[0021] Determine whether the voltage difference remains greater than the third voltage difference threshold within the second consecutive preset time period.

[0022] Furthermore, when sorting individual battery cells from highest to lowest voltage, the method for obtaining the voltage of each individual cell is as follows:

[0023] After the second consecutive preset time, when the voltage difference is less than the second voltage difference threshold, the voltage values ​​of all individual cells at the corresponding time are recorded for sorting.

[0024] Optionally, the preset conditions are for the low SOC segment. When the SOC is lower than the second threshold, the specific conditions are as follows:

[0025] Determine if the entire battery pack is in a charging state;

[0026] Within a third consecutive preset time period, the difference between the highest and lowest voltage of a single cell in the battery pack is greater than a third voltage difference threshold, and the lowest voltage is less than a voltage threshold, and the absolute value of the current is less than a second current threshold within the third consecutive preset time period.

[0027] Record the voltage values ​​of all individual cells when all preset conditions are met for sorting.

[0028] Furthermore, to determine whether all individual battery cells have undergone equalization discharge, the specific method is as follows:

[0029] Construct a historical preset equalization count table. When a single cell undergoes equalization, record the corresponding cell number and equalization count on the historical preset equalization count table.

[0030] When the number of equalization cycles corresponding to all cell numbers is greater than or equal to 1, it is determined that all cell numbers have undergone equalization discharge, the historical preset equalization cycle table is cleared, and the preset equalization capacity is reduced.

[0031] Furthermore, the historical preset balancing count table is iterated. When the balancing count of a single cell exceeds the threshold of the first count, and the balancing count of a single cell is still less than 1, the historical preset balancing count table is cleared to zero, and the preset balancing power is increased.

[0032] To achieve the above objectives, another aspect provides a battery shift balancing device, comprising:

[0033] The information acquisition module collects the voltage values ​​of individual battery cells and the current values ​​of the entire battery pack.

[0034] The balance judgment module determines whether the current condition is met.

[0035] The alternating balancing module sorts the individual battery cells from high to low voltage, and discharges the cells with the preset ranking according to the preset balancing capacity. The voltage ranking is updated, and the cells with the preset ranking are discharged according to the preset balancing capacity again until all cells have undergone equalization discharge.

[0036] To achieve the above objectives, another aspect is to provide a storage medium storing several instructions, which a processor loads to execute the aforementioned battery balancing method.

[0037] To achieve the above objectives, another aspect is to provide a battery management system for the management and control of lithium iron phosphate batteries, including the aforementioned battery balancing device and / or the aforementioned storage medium.

[0038] Due to the adoption of the above technical solutions, the present invention has the following beneficial effects:

[0039] 1. The core of this invention is to take turns and adaptively adjust the step size to bring all cells to a state with a high SOC ranking. By capturing the cell voltage in a specific state, the invention balances the cells with the highest adaptive trigger voltage each time, ensuring high SOC consistency among the cells.

[0040] 2. This invention dynamically adjusts the preset equalization charge based on historical preset equalization frequency data, i.e., the leakage rate difference between individual cells, achieving adaptive adjustment and maintaining the SOC of individual cells at a consistently high level. When the leakage rate difference between individual cells is large, the preset equalization charge of each cell adaptively increases to prevent individual cell voltage deviations from causing the entire pack to become unusable; when the leakage rate difference between individual cells is small, the preset equalization charge adaptively decreases to prevent over-equalization and ineffective power waste.

[0041] 3. This invention employs a rotating balancing approach, eliminating the need for precise calculation of SOC differences between individual cells and subsequent balancing based on these differences. It only requires identifying a state where the individual cell voltage level accurately reflects the individual cell SOC level. Although individual cell voltage ranking does not equate to individual cell SOC ranking, this does not affect the effectiveness of this solution. A Spearman correlation coefficient greater than 0.6 between individual cell voltage and individual cell SOC is sufficient to allow for multiple balancing processes, where higher-ranked cells can tolerate this error.

[0042] 4. This invention proposes a method for identifying individual cell voltage rankings that can represent individual cell SOC rankings for low, medium, and high SOC scenarios, thereby improving the efficiency of equalization implementation. When the aging levels of cells within a package are inconsistent, the triggering schemes for the medium and high SOC ranges can be selectively retained to align the tops of all cells, preventing ineffective equalization and power waste caused by chaotic alignment strategies.

[0043] It should be noted that the terms "first," "second," and similar terms used in this article are merely for describing the constituent elements of the technical solution and do not constitute a limitation on the technical solution, nor should they be interpreted as an indication or implication of the importance of the corresponding elements; elements with terms such as "first," "second," or similar terms indicate that at least one of the elements is included in the corresponding technical solution. Attached Figure Description

[0044] To more clearly illustrate the technical solution of the present invention and facilitate a further understanding of its technical effects, features, and objectives, the present invention will be described in detail below with reference to the accompanying drawings. The drawings constitute an essential part of the specification and are used together with Embodiment 1 of the present invention to illustrate the technical solution of the present invention, but do not constitute a limitation on the present invention.

[0045] The same reference numerals in the attached diagrams represent the same parts, specifically:

[0046] Figure 1 This is a schematic diagram of the OCV-SOC curve of a traditional lithium iron phosphate battery.

[0047] Figure 2 This is a schematic diagram of the overall process of Example 1.

[0048] Figure 3This diagram illustrates the change in cell SOC when no balancing strategy was used in Experiment 1.

[0049] Figure 4 This diagram illustrates the change in the cell's difference from the minimum SOC when no balancing strategy was used in Experiment 1.

[0050] Figure 5 This diagram illustrates the SOC range variation of cells with different leakage rates when no equalization strategy was used in Experiment 1.

[0051] Figure 6 This diagram illustrates the change in SOC difference of cells with different leakage rates after adopting this equalization strategy in Experiment 1.

[0052] Figure 7 This diagram illustrates the SOC range variation of cells with different leakage rates after adopting this equalization strategy in Experiment 1.

[0053] Figure 8 This diagram illustrates the change in cell SOC when no balancing strategy was used in Experiment 2 to verify the results.

[0054] Figure 9 This diagram illustrates the change in the cell's difference from the minimum SOC when no balancing strategy was used in Experiment 2.

[0055] Figure 10 To verify the changes in the SOC range of the battery cell when no equalization strategy was used and the leakage rate changed abruptly in Experiment 2.

[0056] Figure 11 This diagram illustrates the change in SOC difference of the battery cell under the condition of sudden change in leakage rate after adopting this equalization strategy in Experiment 2.

[0057] Figure 12 This diagram illustrates the changes in the difference between each cell and the minimum SOC under the condition of sudden change in leakage rate after adopting this equalization strategy in Experiment 2.

[0058] Figure 13 This diagram illustrates the change in the SOC range of the battery cell under the condition of a sudden change in leakage rate after adopting this equalization strategy in Experiment 2. Detailed Implementation

[0059] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Of course, the specific embodiments described below are merely illustrative of the technical solutions of the present invention, and not intended to limit the invention. Furthermore, the parts described in the embodiments or drawings are merely illustrative examples of relevant parts of the present invention, and not the entirety of the invention.

[0060] Example 1:

[0061] A battery rotation balancing method, such as Figure 2As shown, the specific steps are as follows:

[0062] S1. Collect the voltage value of individual cells and the current value of the entire battery pack.

[0063] In this embodiment, the voltage values ​​of all individual cells and the current value of the entire battery pack are collected in the BMS at fixed intervals. The current is set to be negative during charging and positive during discharging.

[0064] S2. When the preset conditions are met, sort the individual battery cells from high to low voltage.

[0065] In this embodiment, the preset condition targets the high SOC segment. When the SOC is higher than the first threshold, the specific conditions are as follows:

[0066] S21. Determine if the battery pack is in a charging state: The current value of the battery pack is continuously negative.

[0067] S22. Under the premise that step S21 continues to be true, determine whether the difference between the highest single-cell voltage and the lowest single-cell voltage in the package, i.e. the voltage range, is greater than a certain threshold.

[0068] S23. Under the premise that step S22 continues to be true, calculate the voltage range multiple times at a fixed time period, and determine whether the range increases sequentially each time.

[0069] S24. When the condition in step S23 is met, record all individual voltage values ​​under the latest voltage range increase in real time, and overwrite the old voltage values ​​with the new voltage values.

[0070] S25. When the condition in step S23 is no longer met, the last recorded unit voltage value in step S24 is used in step S3.

[0071] S3. For the battery cells with the preset ranking, discharge them evenly according to the preset equalization power.

[0072] In step S3, specifically, the cell numbers are sorted from high to low voltage, and a pre-defined equalization charge is preset for the cells at the top of the list. Subsequent cells in this group are then equalized according to this equalization charge.

[0073] S4. Update the voltage sorting and repeatedly discharge the battery cells with the preset ranking according to the preset equalization charge until all battery cells have undergone equalization discharge.

[0074] When performing the turn-based balancing in step S4, it is done using a historical preset balancing count table. The specific steps are as follows:

[0075] S41. Based on the historical preset balance count table, determine whether there are any single-unit counts that are 0.

[0076] If the determination in step S41 is yes, it means that the cell with zero overvoltage counts has not yet reached the state of being ranked high in overvoltage, and proceeds to step S42. If the determination in step S41 is no, it means that after steps S3 and S4, all the cells have entered the state of being ranked high in overvoltage. The current preset equalization capacity value can ensure that the voltage of all cells is at the top in turn. At this time, the historical preset equalization count table is cleared to zero, and the preset equalization capacity required in the next step S3 is lowered by one level.

[0077] S42. Traverse the historical preset balance count table and determine if there is any single entity whose count exceeds the threshold:

[0078] S43. If the determination in step S42 is yes, it means that after discharging the top-ranked cells downwards for n consecutive times, there are still cells whose voltage has not entered the top-ranked state. At this time, the historical preset equalization count table is cleared to zero, and the preset equalization power required in the next step S3 is increased by one level.

[0079] S44. If the determination in step S42 is negative, maintain the preset equalization power required in the next step S3, and keep the preset equalization power value unchanged.

[0080] Example 2:

[0081] A battery rotation balancing method, the specific steps of which are as follows:

[0082] S1. Collect the voltage value of individual cells and the current value of the entire battery pack.

[0083] In this embodiment, the voltage values ​​of all individual cells and the current value of the entire battery pack are collected in the BMS at fixed intervals. The current is set to be negative during charging and positive during discharging.

[0084] S2. When the preset conditions are met, sort the individual battery cells from high to low voltage.

[0085] The preset conditions apply to the SOC segment. When the SOC is lower than the first threshold and greater than the second threshold, the specific conditions are as follows:

[0086] S21. Determine that the battery pack is currently charging.

[0087] S22. Determine that the voltage range within the package is less than a set threshold for a continuous period of time, and the current is constant and less than a set threshold during this period of time.

[0088] S23. Continuously monitor the voltage range within the package and determine whether the voltage range exceeds a predetermined threshold for a preset time.

[0089] When conditions S24 and S23 are met, record the latest voltage values ​​of all individual cells in real time.

[0090] S25. Continuously monitor the voltage range within the package and determine whether the voltage range is again less than the voltage range threshold in step S22, and whether this continues for a period of time.

[0091] S26. Use the single-unit voltage value recorded last time in step S24 for the calculation in step S3.

[0092] S3. For the battery cells with the preset ranking, discharge them evenly according to the preset equalization power.

[0093] In step S3, specifically, the cell numbers are sorted from high to low voltage, and a pre-defined equalization charge is preset for the cells at the top of the list. Subsequent cells in this group are then equalized according to this equalization charge.

[0094] S4. Update the voltage sorting and repeatedly discharge the battery cells with the preset ranking according to the preset equalization charge until all battery cells have undergone equalization discharge.

[0095] When performing the turn-based balancing in step S4, it is done using a historical preset balancing count table. The specific steps are as follows:

[0096] S41. Based on the historical preset balance count table, determine whether there are any single-unit counts that are 0.

[0097] If the determination in step S41 is yes, it means that the cell with zero overvoltage counts has not yet reached the state of being ranked high in overvoltage, and proceeds to step S42. If the determination in step S41 is no, it means that after steps S3 and S4, all the cells have entered the state of being ranked high in overvoltage. The current preset equalization capacity value can ensure that the voltage of all cells is at the top in turn. At this time, the historical preset equalization count table is cleared to zero, and the preset equalization capacity required in the next step S3 is lowered by one level.

[0098] S42. Traverse the historical preset balance count table and determine if there is any single entity whose count exceeds the threshold:

[0099] S43. If the determination in step S42 is yes, it means that after discharging the top-ranked cells downwards for n consecutive times, there are still cells whose voltage has not entered the top-ranked state. At this time, the historical preset equalization count table is cleared to zero, and the preset equalization power required in the next step S3 is increased by one level.

[0100] S44. If the determination in step S42 is negative, maintain the preset equalization power required in the next step S3, and keep the preset equalization power value unchanged.

[0101] Example 3:

[0102] A battery rotation balancing method, the specific steps of which are as follows:

[0103] S1. Collect the voltage value of individual cells and the current value of the entire battery pack.

[0104] In this embodiment, the voltage values ​​of all individual cells and the current value of the entire battery pack are collected in the BMS at fixed intervals. The current is set to be negative during charging and positive during discharging.

[0105] S2. When the preset conditions are met, sort the individual battery cells from high to low voltage.

[0106] In this embodiment, the preset condition targets the low SOC segment. When the SOC is lower than the second threshold, the specific conditions are as follows:

[0107] S21. Determine that the battery pack is in a non-charging state at this time;

[0108] S22. Determine that within a continuous period of time, the voltage range within the package is greater than a certain threshold, the lowest voltage within the package is less than a certain threshold, and the absolute value of the constant current during this period is also less than a certain threshold.

[0109] When the conditions of step S22 are met, record the voltage values ​​of all individual cells for calculation in step S3.

[0110] S3. For the battery cells with the preset ranking, discharge them evenly according to the preset equalization power.

[0111] In step S3, specifically, the cell numbers are sorted from high to low voltage, and a pre-defined equalization charge is preset for the cells at the top of the list. Subsequent cells in this group are then equalized according to this equalization charge.

[0112] S4. Update the voltage sorting and repeatedly discharge the battery cells with the preset ranking according to the preset equalization charge until all battery cells have undergone equalization discharge.

[0113] When performing the turn-based balancing in step S4, it is done using a historical preset balancing count table. The specific steps are as follows:

[0114] S41. Based on the historical preset balance count table, determine whether there are any single-unit counts that are 0.

[0115] If the determination in step S41 is yes, it means that the cell with zero overvoltage counts has not yet reached the state of being ranked high in overvoltage, and proceeds to step S42. If the determination in step S41 is no, it means that after steps S3 and S4, all the cells have entered the state of being ranked high in overvoltage. The current preset equalization capacity value can ensure that the voltage of all cells is at the top in turn. At this time, the historical preset equalization count table is cleared to zero, and the preset equalization capacity required in the next step S3 is lowered by one level.

[0116] S42. Traverse the historical preset balance count table and determine if there is any single entity whose count exceeds the threshold:

[0117] S43. If the determination in step S42 is yes, it means that after discharging the top-ranked cells downwards for n consecutive times, there are still cells whose voltage has not entered the top-ranked state. At this time, the historical preset equalization count table is cleared to zero, and the preset equalization power required in the next step S3 is increased by one level.

[0118] S44. If the determination in step S42 is negative, maintain the preset equalization power required in the next step S3, and keep the preset equalization power value unchanged.

[0119] As can be seen from Examples 1, 2 and 3, the preset conditions for alternating balancing can be designed separately according to SOC (high, medium and low), and any one or more of SOC (high, medium and low) can be used as the admission conditions.

[0120] Verification Experiment 1:

[0121] In a battery pack with 12 LFP cells assembled in series and all cells at 100% State of Health (SOH), assume the initial SOC and leakage rate of all cells are as shown in the table below:

[0122] Table 1: Initial SOC and Leakage Rate of 12 LFP Cells

[0123]

[0124] Cells 11 and 12 showed significantly higher leakage rates than the other cells, simulating a scenario of abnormal leakage in individual cells in a real vehicle power battery environment.

[0125] When no balancing strategy is implemented, the SOC change trend of all cells after 60 days is as follows: Figure 3 As shown, the changing trends of each cell's difference from the minimum SOC are as follows: Figure 4 As shown.

[0126] The SOC difference between cells increased continuously over 60 days, and by the 60th day, the SOC difference within the pack had exceeded 5%. Figure 5 As shown:

[0127] Assuming that in step S3, the top 40% of battery cells by voltage are selected each time, the maximum number of times n is allowed in step S43 is 5, and there are seven levels of equalization power in step S5, as shown in the table below:

[0128] Table 2: Balanced power consumption at different power levels

[0129] gear 1 2 3 4 5 6 7 Each power balancing 0.00％ 0.05％ 0.10％ 0.20％ 0.30％ 0.40％ 0.50％

[0130] Assuming step 2 can be triggered once a day and can balance all target battery levels, then the changes in the difference between each cell and the minimum SOC over 60 days are as follows: Figure 6 As shown, the SOC difference between cells converges to approximately 0.2% within 60 days. Figure 7 As shown.

[0131] By comparison, it is evident that after applying the equalization strategy of this invention, the SOC dispersion among the cells decreases rapidly and eventually converges to around 0%. Even with differences in self-discharge levels among the cells, the SOC consistency among the cells can still be optimized to a high level. The details of the SOC changes of the 12 cells are shown in the table below.

[0132] Table 3: Details of SOC changes in 12 cells from Example 1

[0133]

[0134]

[0135] Verification Experiment 2:

[0136] In a battery pack with 12 LFP cells assembled in series and all cells having a state of aging (SOH) of 100%, assume that the initial SOC value and leakage rate of all cells are as shown in the table below.

[0137] Table 4: Initial SOC and Leakage Rate of 12 LFP Cells

[0138]

[0139] For the first 20 days, the leakage rate of all cells was very low, controlled at 0.005% per day. After the 20th day, the leakage rate of cells 11 and 12 was significantly higher than that of other cells, simulating the abnormal leakage scenario of individual cells in a real vehicle power battery environment.

[0140] When no balancing strategy is involved, the SOC change trend of all cells after 90 days and the change trend of the difference between each cell and the minimum SOC are as follows: Figure 8 and Figure 9 As shown. From day 20 to day 90, the SOC difference between cells continuously increased, and by day 90, the SOC difference within the pack had exceeded 10%, as... Figure 10 As shown.

[0141] Assuming that in step S3, the top 40% of battery cells by voltage are selected each time, the maximum number of times n is allowed in step S43 is 5, and there are seven levels of equalization power in step S5, as shown in the table below:

[0142] Table 5: Balanced power consumption at different power levels

[0143] gear 1 2 3 4 5 6 7 Each power balancing 0.00％ 0.05％ 0.10％ 0.20％ 0.30％ 0.40％ 0.50％

[0144] Assuming step 2 can be triggered once a day and can evenly balance all target battery levels, then the changes in the difference between each cell and the minimum SOC over 90 days are as follows: Figure 11 and Figure 12 As shown.

[0145] During the first 20 days, due to the relatively low leakage rates of all cells, this solution primarily balanced the initial State of Charge (SOC) differences, optimizing the intra-pack SOC range from 2% to approximately 0.2%. Starting from day 20, due to sudden abnormal leakage in cells 11 and 12, the balancing level of this solution was adaptively adjusted. During this process, the maximum increase in the SOC range was only 1.3% (around day 50), subsequently converging to a high consistency level of less than 0.5%. Figure 12 and Figure 13 As shown.

[0146] contrast Figure 13 and Figure 10 It can be clearly seen that after applying the equalization strategy of this invention, the SOC range between cells remains at a low value. Even if the leakage current level between cells changes abruptly, this solution can still optimize the SOC consistency between cells to a high level. The specific SOC change details are shown in the table below.

[0147] Table 6: Details of SOC changes in 12 cells in Example 2

[0148]

[0149]

[0150]

[0151] Example 4:

[0152] A battery shift balancing device, comprising:

[0153] The information acquisition module collects the voltage values ​​of individual battery cells and the current values ​​of the entire battery pack.

[0154] The balance judgment module determines whether the current condition is met.

[0155] The alternating balancing module sorts the individual battery cells from high to low voltage, and discharges the cells with the preset ranking according to the preset balancing capacity. The voltage ranking is updated, and the cells with the preset ranking are discharged according to the preset balancing capacity again until all cells have undergone equalization discharge.

[0156] It should be noted that the above embodiments are only for more clearly illustrating the technical solution of the present invention. Those skilled in the art will understand that the implementation of the present invention is not limited to the above content. Any obvious changes, substitutions or replacements made based on the above content do not exceed the scope of the technical solution of the present invention. Other implementations will also fall within the scope of the present invention without departing from the concept of the present invention.

Claims

1. A battery alternating balancing method, characterized in that, The specific method is as follows: Collect the voltage values ​​of individual battery cells and the current values ​​of the entire battery pack; When the preset conditions are met, the individual battery cells are sorted from high to low voltage. For individual cells with preset rankings, discharge them evenly according to preset equalization power. Update the voltage sorting and repeatedly discharge the battery cells with the preset ranking according to the preset equalization charge until all battery cells have undergone equalization discharge.

2. The battery alternating balancing method as described in claim 1, characterized in that, The preset conditions are for the high SOC segment. When the SOC is higher than the first threshold, the specific conditions are as follows: Determine if the entire battery pack is in a charging state; The difference between the highest and lowest voltages of individual cells within the battery pack is determined to be greater than the first voltage difference threshold.

3. The battery alternating balancing method as described in claim 2, characterized in that, When sorting individual battery cells by voltage from high to low, the voltage of each individual cell is obtained as follows: Within a fixed time period, the voltage range between the highest and lowest voltages of a single cell is calculated multiple times to determine whether the voltage range increases sequentially. If the voltage range increases sequentially, record the voltage values ​​of all individual cells in the latest fixed time period for sorting. If the voltage range does not increase sequentially, the voltage values ​​of all individual cells in the last fixed time period when the voltage range decreases are recorded for sorting.

4. The battery alternating balancing method as described in claim 1, characterized in that, The preset conditions apply to the SOC segment. When the SOC is lower than the first threshold and greater than the second threshold, the specific conditions are as follows: Determine if the entire battery pack is in a charging state; Within a first consecutive preset time period, it is determined that the difference between the highest and lowest voltages of individual cells in the battery pack is less than a second voltage difference threshold, and the current is less than a first current threshold within the preset time period. Determine whether the voltage difference remains greater than the third voltage difference threshold within the second consecutive preset time period.

5. The battery alternating balancing method as described in claim 4, characterized in that, When sorting individual battery cells by voltage from high to low, the voltage of each individual cell is obtained as follows: After the second consecutive preset time, when the voltage difference is less than the second voltage difference threshold, the voltage values ​​of all individual cells at the corresponding time are recorded for sorting.

6. The battery alternating balancing method as described in claim 1, characterized in that, The preset conditions are for the low SOC segment. When the SOC is lower than the second threshold, the specific conditions are as follows: Determine if the entire battery pack is in a charging state; Within a third consecutive preset time period, the difference between the highest and lowest voltage of a single cell in the battery pack is greater than a third voltage difference threshold, and the lowest voltage is less than a voltage threshold, and the absolute value of the current is less than a second current threshold within the third consecutive preset time period. Record the voltage values ​​of all individual cells when all preset conditions are met for sorting.

7. The battery alternating balancing method as described in claim 1, characterized in that, The specific method to determine whether each individual battery cell has undergone equalization discharge is as follows: Construct a historical preset equalization count table. When a single cell undergoes equalization, record the corresponding cell number and equalization count on the historical preset equalization count table. When the number of equalization cycles corresponding to all cell numbers is greater than or equal to 1, it is determined that all cell numbers have undergone equalization discharge, the historical preset equalization cycle table is cleared, and the preset equalization capacity is reduced.

8. The battery alternating balancing method as described in claim 7, characterized in that, Traverse the historical preset balancing count table. If the balancing count of a single cell exceeds the threshold of the first count, and the balancing count of a single cell is still less than 1, clear the historical preset balancing count table to zero and increase the preset balancing power.

9. A battery alternating balancing device, characterized in that, include: The information acquisition module collects the voltage values ​​of individual battery cells and the current values ​​of the entire battery pack. The balance judgment module determines whether the current condition is met. The alternating balancing module sorts the individual battery cells from high to low voltage, and discharges the battery cells in the preset ranking according to the preset balancing capacity. Update the voltage sorting and repeatedly discharge the battery cells with the preset ranking according to the preset equalization charge until all battery cells have undergone equalization discharge.

10. A storage medium, characterized in that, The system stores several instructions, and the processor loads the instructions to execute the battery balancing method according to any one of claims 1 to 8.

11. A battery management system for the management and control of lithium iron phosphate batteries, characterized in that, It includes the battery shift balancing device of claim 9 and / or the storage medium of claim 10.

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