Battery pack SOC value calibration method and device, storage medium and electric energy equipment

Abstract

The invention discloses a battery pack SOC value calibration method and device, a storage medium and electric energy equipment, and the method comprises the steps: obtaining SOC values of a plurality of target cells in a battery pack, and obtaining a function relation between the SOC values of the cells in the battery pack and the SOC value of the battery pack according to the SOC values of the target cells; and calibrating the SOC value of the battery pack according to the function relationship. According to the method, the performance difference between the battery cells can be effectively handled, and the SOC estimation error caused by the inconsistency of the battery cells is reduced, so that the calibration precision of the SOC value of the whole battery pack is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery management, and in particular to a method for calibrating the SOC value of a battery pack, a device for calibrating the SOC value of a battery pack, a non-volatile readable storage medium, and an electric energy device. Background Art

[0002] In related technologies, battery SOC estimation methods often rely on complex simulation models or equivalent circuit models. These methods require a large amount of experimental data or identify the resistance and capacitance parameters of the battery, then combine advanced algorithms (such as the Black Widow algorithm, feedforward neural network algorithm, least squares method with forgetting factor, random forest, etc.) for model training, and finally use machine learning models to estimate SOC. Although these methods can provide estimation results under certain conditions, they still require a large amount of simulation experimental data to ensure the accuracy of the model, and it is often difficult to truly reflect the performance of the battery under different operating conditions. In addition, these methods only estimate the SOC of a single battery cell. In module-level SOC calibration, the differences between the individual batteries in the battery pack are not effectively considered, resulting in large errors in the estimation of the battery pack SOC. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one object of the present invention is to provide a method for calibrating the SOC value of a battery pack. This method can effectively address performance differences between battery cells, reduce SOC estimation errors caused by cell inconsistencies, and thus improve the calibration accuracy of the SOC value of the entire battery pack.

[0004] A second objective of the present invention is to provide a device for calibrating the SOC value of a battery pack.

[0005] A third object of the present invention is to provide a non-volatile readable storage medium.

[0006] A fourth object of the present invention is to provide an electric energy device.

[0007] In order to achieve the above-mentioned purpose, the calibration method of the battery pack SOC value of the first aspect embodiment of the present invention includes: obtaining the SOC values of multiple target battery cells in the battery pack; obtaining the functional relationship between the SOC values of the battery cells in the battery pack and the SOC value of the battery pack based on the SOC values of the multiple target battery cells; and calibrating the SOC value of the battery pack based on the functional relationship.

[0008] According to an embodiment of the present invention, a method for calibrating the SOC value of a battery pack obtains the SOC values of multiple target cells in the battery pack and establishes a functional relationship between the cell SOC value and the battery pack SOC value based on these SOC values. This relationship effectively maps the association between the state of a single cell and the overall state of the battery pack. Through this functional relationship, the SOC value of the battery pack can be accurately calibrated. In this process, the SOC value of each target cell represents the state of the cell, while the battery pack SOC value is a comprehensive reflection of the states of multiple cells. By establishing a functional relationship between the cell SOC value and the battery pack SOC value, the present invention can comprehensively consider the SOC performance of each cell and optimize the calibration of the overall SOC value of the battery pack. Since different cells in a battery pack may have performance differences, relying solely on the SOC value of a single cell is prone to introduce errors. By establishing a functional relationship, the SOC estimation error caused by the performance differences between cells can be effectively reduced, thereby improving the calibration accuracy of the SOC value of the entire battery pack.

[0009] In some embodiments, obtaining a functional relationship between the SOC values of the battery cells in the battery pack and the SOC value of the battery pack based on the SOC values of the multiple target battery cells includes: obtaining a functional relationship between the SOC values of the battery cells in the battery pack and the SOC value of the battery pack by using the least recursive squares method based on the SOC values of the multiple target battery cells.

[0010] In some embodiments, each of the target battery cells has a corresponding capacity increment curve, and the SOC value of the target battery cell is obtained based on data of a corresponding target point on the capacity increment curve, and the target point includes at least one of a peak point and a trough point.

[0011] In some embodiments, the target point is a target valley point; the target valley point is located on a curve segment of the capacity increment curve corresponding to a voltage platform jump region of the target battery cell.

[0012] In some embodiments, the capacity increment curve of the target battery cell includes a first valley point and a second valley point, the voltage value corresponding to the first valley point is smaller than the voltage value corresponding to the second valley point, and the target valley point is the second valley point.

[0013] In some embodiments, obtaining the SOC values of multiple target cells in a battery pack includes: obtaining the target point SOC value of each target cell when it reaches the target point; taking the moment when the latest of the multiple target cells reaches the corresponding target point as the calibration point, obtaining the capacity change of each target cell from the corresponding target point to the calibration point; and obtaining the SOC value of the target cell at the calibration point based on the target point SOC value and the capacity change of each target cell.

[0014] In some embodiments, the multiple target battery cells include a first target battery cell and a second target battery cell, the first target battery cell being the first battery cell among the multiple battery cells to reach the charging cut-off voltage under the charging condition of the battery pack, and the second target battery cell being the first battery cell among the multiple battery cells to reach the discharging cut-off voltage under the discharging condition of the battery pack.

[0015] In some embodiments, under charging conditions, the SOC value of the first target battery cell is the sum of the target point SOC value of the first target battery cell and the first SOC ratio, the first SOC ratio is the ratio of the first capacity change to the current capacity of the first target battery cell, and the first capacity change is the capacity change of the first target battery cell from the corresponding target point to the calibration point; the SOC value of the second target battery cell is the target point SOC value of the second target battery cell at the corresponding target point.

[0016] In some embodiments, under discharge conditions, the SOC value of the first target battery cell is the target point SOC value of the first target battery cell at the corresponding target point; the SOC value of the second target battery cell is the difference between the target point SOC value of the second target battery cell and the second SOC ratio, the second SOC ratio is the ratio of the second capacity change to the current capacity of the second target battery cell, and the second capacity change is the capacity change of the second target battery cell from the corresponding target point to the calibration point.

[0017] In some embodiments, calibrating the SOC value of the battery pack according to the functional relationship includes: determining a first SOC weight of the first target battery cell and a second SOC weight of the second target battery cell according to the functional relationship; and obtaining the SOC value of the battery pack according to the SOC value of the first target battery cell and the first SOC weight and the SOC value of the second target battery cell and the second SOC weight.

[0018] In some embodiments, the calibration method further includes: under a fully charged or fully discharged condition, obtaining an SOH value of the battery pack according to an SOC value of the battery pack and a capacity variation of the battery pack from the calibration point to a fully charged or fully discharged condition.

[0019] In some embodiments, the calibration method also includes: under a fully charged condition, obtaining a capacity increment of the first target battery cell from the corresponding target point to the charging cutoff; obtaining an SOC value of the first target battery cell based on the capacity increment and the target point SOC value of the first target battery cell; and updating the current capacity of the first target battery cell to the SOC value of the first target battery cell.

[0020] In some embodiments, the calibration method further includes: under a full discharge condition, obtaining the capacity reduction of the second target battery cell from the start of discharge to the target point corresponding to the second target battery cell; obtaining the SOC value of the second target battery cell based on the capacity reduction and the target point SOC value of the second target battery cell; and updating the current capacity of the second target battery cell to the SOC value of the second target battery cell.

[0021] In some embodiments, the target battery cell is determined based on stored battery history data.

[0022] In order to achieve the above-mentioned purpose, the calibration device of the battery pack SOC value of the second embodiment of the present invention includes: at least one processor; a memory communicatively connected to the at least one processor; the memory stores a computer program that can be executed by the at least one processor, and when the at least one processor executes the computer program, it implements the calibration method of the battery pack SOC value described in the above embodiment.

[0023] According to an embodiment of the present invention, a battery pack SOC calibration device employs at least one processor, executing a computer program implementing the battery pack SOC calibration method described in the above embodiments, to obtain the SOC values of multiple target cells in the battery pack and, based on these SOC values, establish a functional relationship between the cell SOC values and the battery pack SOC value. This relationship effectively maps the correlation between the state of individual cells and the overall state of the battery pack. This functional relationship enables precise calibration of the battery pack SOC value. In this process, the SOC value of each target cell represents the state of that cell, while the battery pack SOC value is a comprehensive reflection of the states of multiple cells. By establishing a functional relationship between the cell SOC values and the battery pack SOC value, the present invention comprehensively considers the SOC performance of each cell and optimizes the calibration of the overall battery pack SOC value. Because different cells in a battery pack may have varying performance, relying solely on the SOC value of a single cell can easily introduce errors. By establishing this functional relationship, SOC estimation errors caused by performance differences between cells can be effectively reduced, thereby improving the calibration accuracy of the overall battery pack SOC value.

[0024] In order to achieve the above-mentioned purpose, the non-volatile readable storage medium of the third aspect of the embodiment of the present invention stores a computer program thereon, characterized in that when the computer program is executed, the calibration method of the battery pack SOC value described in the above embodiment is implemented.

[0025] According to the non-volatile readable storage medium of an embodiment of the present invention, by adopting the battery pack SOC value calibration method described in the above embodiment, it is possible to effectively address the performance differences between battery cells, reduce the SOC estimation error caused by battery cell inconsistency, and thus improve the calibration accuracy of the SOC value of the entire battery pack.

[0026] In order to achieve the above-mentioned purpose, the electric energy equipment of the fourth embodiment of the present invention includes: a battery pack and a calibration device for the SOC value of the battery pack as described in the above embodiment, wherein the battery pack includes multiple battery cells connected in series or in parallel, and the calibration device is used to calibrate the SOC value and SOH value of the battery pack and calibrate the capacity of the target battery cell among the multiple battery cells.

[0027] According to an embodiment of the present invention, the electric energy device employs the above-mentioned battery pack SOC value calibration device, and based on the obtained SOC values of multiple target cells in the battery pack, a functional relationship can be established between the cell SOC value and the battery pack SOC value. This relationship effectively maps the association between the state of a single cell and the overall state of the battery pack. Through this functional relationship, the battery pack SOC value can be accurately calibrated. In this process, the SOC value of each target cell represents the state of that cell, while the battery pack SOC value is a comprehensive reflection of the states of multiple cells. Furthermore, the present invention can also calibrate the capacity of the target cell among multiple cells based on this functional relationship, thereby ensuring the consistency of the capacity of each cell in the battery pack. At the same time, the present invention can calibrate the battery pack's SOH value based on the overall SOC value of the battery pack. Because different cells in a battery pack may have performance differences, relying solely on the SOC value of a single cell is prone to introducing errors. By establishing a functional relationship between the battery cell SOC value and the battery pack SOC value, not only can the calibration of the battery pack SOC value be optimized, but the SOC estimation error caused by battery cell performance differences can also be effectively reduced, thereby improving the calibration accuracy of the SOC value and SOH value of the entire battery pack.

[0028] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which: Figure 1 is a flow chart of a method for calibrating a battery pack SOC value according to one embodiment of the present invention; Figure 2 is a schematic diagram of a capacity increment curve for charging a target battery cell according to one embodiment of the present invention; Figure 3 is a schematic diagram of voltage and SOC calibration curves of multiple target battery cells in a battery pack according to one embodiment of the present invention; Figure 4 is an overall flow chart of a method for calibrating a battery pack SOC value according to one embodiment of the present invention; Figure 5 is a block diagram of a device for calibrating a battery pack SOC value according to an embodiment of the present invention; Figure 6 is a block diagram of an electric energy device according to an embodiment of the present invention.

[0030] Reference numerals: Power equipment 100; Battery pack SOC value calibration device 1; battery pack 2; Processor 11; memory 12. DETAILED DESCRIPTION

[0031] The embodiments of the present invention will be described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. The embodiments of the present invention will be described in detail below.

[0032] Reference below Figures 1-4 A method for calibrating the SOC value of a battery pack according to an embodiment of the present invention is described.

[0033] Figure 1 FIG. 1 is a flow chart of a method for calibrating a battery pack SOC value according to an embodiment of the present invention. Figure 1 As shown, the battery pack SOC value calibration method according to the embodiment of the present invention includes steps S1-S3.

[0034] S1, obtaining the SOC values of multiple target cells in the battery pack.

[0035] In some embodiments, a battery pack can be a single battery unit composed of multiple cells, which can be configured in series or parallel within the battery pack to provide the desired voltage and capacity output. Each cell has its own SOC (State of Charge) value, which indicates the degree to which the cell currently stores electrical energy and can be expressed as a percentage. The SOC value of a cell reflects its remaining charge and is a key parameter for assessing battery health and predicting battery life. Therefore, accurately obtaining the SOC value of a cell is crucial to evaluating the performance of a battery pack.

[0036] In some embodiments, in a battery pack, multiple target cells may refer to specific cells selected for obtaining SOC values. These target cells may be some of the cells in the battery pack and may be randomly selected or selected based on certain criteria (e.g., cell health, usage time, or load conditions). The SOC values of different cells may vary due to factors such as cell manufacturing differences, aging, and temperature. Therefore, by obtaining the SOC values of multiple target cells, accurate data support can be provided for establishing a functional relationship between the multiple target cell SOC values and the battery pack SOC value.

[0037] S2, obtaining a functional relationship between the SOC values of the battery cells in the battery pack and the SOC value of the battery pack according to the SOC values of the multiple target battery cells.

[0038] In some embodiments, the SOC value of a battery pack may be a combination of the SOC values of multiple cells therein through a certain functional relationship. Since the SOC value of each cell contributes to the overall SOC value of the battery pack, the functional relationship between the battery pack SOC value and the cell SOC value can be obtained by detecting the SOC values of multiple target cells and using statistical methods or other mathematical modeling techniques. Through this process, the SOC values of multiple cells in the battery pack can be mapped to the SOC value of the battery pack, and then an accurate mathematical model can be established. This model can reflect the overall charge state of the battery pack and compensate for the differences between cells, such as changes in SOC value caused by factors such as cell aging and capacity attenuation, thereby ensuring that the calculation of the battery pack SOC value is more accurate.

[0039] S3, calibrating the SOC value of the battery pack according to the functional relationship.

[0040] In some embodiments, by establishing a functional relationship between the cell SOC value and the battery pack SOC value, the battery pack SOC value can be accurately calibrated. This process can be periodically updated to account for the effects of battery aging. The calibrated SOC value provides more accurate information to the battery management system, which in turn influences charging and discharging strategies and the remaining useful life prediction of the battery.

[0041] According to an embodiment of the present invention, a method for calibrating the SOC value of a battery pack obtains the SOC values of multiple target cells in the battery pack and establishes a functional relationship between the cell SOC value and the battery pack SOC value based on these SOC values. This relationship effectively maps the association between the state of a single cell and the overall state of the battery pack. Through this functional relationship, the SOC value of the battery pack can be accurately calibrated. In this process, the SOC value of each target cell represents the state of the cell, while the battery pack SOC value is a comprehensive reflection of the states of multiple cells. By establishing a functional relationship between the cell SOC value and the battery pack SOC value, the present invention can comprehensively consider the SOC performance of each cell and optimize the calibration of the overall SOC value of the battery pack. Since different cells in a battery pack may have performance differences, relying solely on the SOC value of a single cell is prone to introduce errors. By establishing a functional relationship, the SOC estimation error caused by the performance differences between cells can be effectively reduced, thereby improving the calibration accuracy of the SOC value of the entire battery pack.

[0042] In some embodiments, obtaining a functional relationship between the SOC values of the battery cells in the battery pack and the SOC value of the battery pack based on the SOC values of multiple target battery cells includes: obtaining a functional relationship between the SOC values of the battery cells in the battery pack and the SOC value of the battery pack by using a least recursive squares (RLS) method based on the SOC values of the multiple target battery cells.

[0043] Among them, in the battery pack, the SOC value of each target cell may be slightly different, especially in the case of long-term use or battery aging, the consistency of the target cells will decrease. Therefore, the functional relationship between the SOC value of the battery cell in the battery pack and the SOC value of the battery pack obtained by a simple weighted average or linear method may not accurately reflect the overall state of the battery pack. The least recursive squares method is a classic mathematical optimization algorithm that is suitable for data fitting problems. It can find the best function match for the data by minimizing the sum of squares of the errors, and thus more accurately estimate the SOC value of the battery pack. This method is particularly suitable for processing SOC values with time series, and can dynamically update and optimize the estimation model to make the calibration results more accurate. In addition, the least recursive squares method can also be used for curve fitting.

[0044] In some embodiments, the least recursive squares method continuously updates the weights so that the system can fit the SOC value that conforms to the actual state with the smallest error. Specifically, the least recursive squares method establishes a fitting model based on the SOC value of each target battery cell, finds the most appropriate functional relationship to describe the relationship between these SOC values, and fits a comprehensive SOC value through iterative calculation as the SOC value of the battery pack. The advantage of the RLS algorithm is that it can continuously adjust the weights in the model according to real-time data, so that in multiple cycles, it can gradually optimize the SOC value, reduce the error, and accurately estimate the overall SOC value of the battery pack. The specific formula of the least recursive squares method is as follows: ; ; Therefore, the recursive least squares (RLS) algorithm can continuously update the estimation results in real-time operation. When a new battery cell SOC value arrives, the RLS algorithm can make timely adjustments to calibrate the battery pack's SOC value. Compared with traditional linear regression or weighted averaging methods, RLS can dynamically adjust based on the error, making the SOC value estimate of the entire battery module more accurate. RLS can handle inconsistencies that gradually accumulate during battery cell use, such as large SOC deviations in certain cells or aging of some cells. By continuously adjusting the weights, the RLS algorithm can reduce the negative impact of these cells on the overall battery pack SOC estimate.

[0045] In some embodiments, each target cell has a corresponding incremental capacity curve. The incremental capacity curve can be obtained using incremental capacity (IC) analysis. IC analysis is a non-invasive (non-destructive) analysis method based on the electrochemical reaction characteristics of lithium batteries during charging. This method assesses the cell's condition by monitoring the change in capacity during the charge and discharge process. The incremental capacity curve describes the relationship between the change in capacity and the change in voltage of the target cell during the charge and discharge process.

[0046] In some embodiments, the SOC value of the target battery cell is obtained based on data of a target point on the corresponding capacity increment curve, where the target point includes at least one of a peak point and a valley point.

[0047] like Figure 2 As shown, the capacity increment curve has multiple peak points and multiple trough points. During the charging process, the capacity increment curve shows the capacity increment characteristics of the battery. Each peak point in the curve represents the intensity of the electrochemical reaction of the battery at different stages of the charging process. Each peak has a specific peak area, peak height and voltage position corresponding to the peak axis. These characteristics can be used to distinguish different stages of the battery state. The position and height information of the peak points and trough points in the capacity increment curve reflect the internal state of the battery. By analyzing these changes, the internal condition of the battery, such as the battery health status and performance changes, can be indirectly understood. By analyzing the changes in the characteristic parameters of the capacity increment curve, changes in the state of the lithium battery can be qualitatively identified and quantitatively analyzed. The main causes of these changes include: the degree of loss of active materials, the loss of lithium ions, and the discharge and charging conditions.

[0048] Specifically, as the battery is cycled, the active material may gradually be lost, and changes in the capacity increment curve can reflect this loss. For example, a decrease in certain peaks may indicate a decrease in the available amount of active material. The capacity drop of a lithium battery is often related to the "failure" or "capture" of lithium ions inside the battery, and the characteristic changes in the capacity increment curve can reflect the loss of lithium ions. Each valley peak represents a different electrochemical reaction intensity, which may involve the insertion or extraction of lithium ions. Changes in the reaction intensity can reflect the efficiency of the chemical reaction inside the battery. The capacity increment curve can also be used to analyze the charging or discharging process of the battery. For example, by observing the capacity increment curves under different SOCs, the performance of the battery during the charging and discharging process can be judged.

[0049] In some embodiments, the capacity increment curve is extracted using the formula: ; in, Indicates the charging capacity, Represents the open-circuit voltage. EVI (Equal Voltage Interval, EVI) indicates that the IC value is calculated at equal voltage intervals. That is, a fixed voltage change is set, and the ratio of the capacity change to the voltage change is calculated under that voltage change.

[0050] In some embodiments, the target point is a target valley point, located on the curve segment of the capacity increment curve corresponding to the voltage plateau transition region of the target cell. The target valley point corresponds to a smaller SOC range, so it can more accurately reflect the current SOC state of the cell, providing a more precise calibration result.

[0051] In some embodiments, identifying the target valley point helps accurately assess the SOC value of the battery cell and understand the performance limits and health status of the battery cell during the charge and discharge process. By selecting the appropriate target valley point, the accuracy of the SOC value estimation can be improved, helping to achieve more precise battery management. Therefore, the target valley point represents the critical state of the battery cell during the charge and discharge process and directly reflects the performance and health of the battery cell.

[0052] In some embodiments, the voltage plateau transition region can refer to the voltage changes within a specific section of a cell's charge and discharge process. For example, during charging, the cell's voltage will experience a slow increase (voltage plateau), and then rapidly change when the cell is nearly fully charged or at a specific reaction stage. The target valley point is located in this plateau transition region, enabling the capture of more subtle changes in SOC, thereby enabling precise SOC calibration.

[0053] In some embodiments, as Figure 2 As shown in the figure, taking the charging condition as an example, the capacity increment curve of the target cell includes the first and second valley points. The voltage corresponding to the first valley point is lower than that corresponding to the second valley point, indicating that the first valley point corresponds to the early or middle reaction stage of the cell. During these stages, the electrochemical reaction of the cell has not yet reached a steady state, and the differences between cells may be large. Therefore, choosing the first valley point as the reference for SOC calibration may result in large errors.

[0054] In some embodiments, the target valley point is the second valley point. Based on a large amount of experimental data statistics, the SOC value at the second valley point is stable and does not shift with battery aging. The remaining peak points or valley points may shift. The following is a data table of the SOC values of the second valley point of actual battery cells after aging, as shown in Table 1: Table 1 SOC values corresponding to the second valley point of actual battery cells at different aging stages

[0055] In summary, Table 1 shows the changes in the battery cell's SOH (state of health), capacity, and SOC value corresponding to the second valley point at different charge and discharge cycles. As the number of cycles increases, the battery cell's SOH and capacity gradually decrease, while the SOC value corresponding to the second valley point fluctuates within a relatively stable range (approximately between 62% and 64%). Estimating the SOC value using the second valley point of the incremental capacity curve provides more accurate SOC values than traditional methods, especially when the battery cell has experienced a high number of cycles and performance degradation. By analyzing this data, we can better understand the battery cell's charging process and state changes, thereby improving the accuracy and reliability of the battery management system.

[0056] In some embodiments, obtaining the SOC values of multiple target cells in a battery pack includes: obtaining a target point SOC value of each target cell when it reaches a target point, using the time when the latest of the multiple target cells reaches the corresponding target point as a calibration point, and obtaining a capacity change of each target cell from the corresponding target point to the calibration point. The SOC value of the target cell at the calibration point is obtained based on the target point SOC value and the capacity change of each target cell.

[0057] Specifically, the capacity increment curve for each target cell has multiple peaks and valleys. The target valley is selected here as the target point for obtaining the SOC value. When this target point is reached, the cell's state can be represented by a precise SOC value, which is the target point SOC value. Because each cell may have different charge and discharge characteristics, their SOC values when reaching the target point may vary. Therefore, the first step is to obtain the SOC value corresponding to each target cell in its voltage platform transition region (i.e., the target valley).

[0058] Furthermore, multiple target cells may reach their respective target points at different times, possibly due to different electrochemical reaction rates within the cells or inconsistent charge and discharge conditions. To ensure the calibration consistency of the SOC value of the entire battery pack, a unified reference time point can be selected. In this step, the time when the target point is reached latest among the multiple target cells is selected as the calibration point. This is to avoid inaccuracies caused by some cells reaching the trough point prematurely. The cell that reaches the target point latest represents the extreme state of the cell in the module, which helps to improve the accuracy of the overall SOC value estimation.

[0059] Furthermore, using the cell that reaches the target point last as the calibration point, the capacity change of each target cell from the time it reaches the target point to the unified calibration point can be calculated. This capacity change represents the increase or decrease in energy during the charging or discharging process of the cell from the target valley point to the calibration point. In other words, by monitoring the current and time of the cell from the target point to the calibration point, the actual capacity change of the cell during this period can be calculated. The capacity change is an important parameter for SOC estimation because it reflects the capacity change of the cell after the target SOC value.

[0060] Furthermore, by combining the SOC value of each target cell at the target point with its capacity change from the target point to the calibration point, the SOC value of that cell at the calibration point can be calculated. Therefore, the SOC value of each target cell is a combination of its SOC value at the target point and its capacity change. This method, through accurate capacity change calculation, can provide a more accurate SOC estimate for each cell, especially when different cells exhibit inconsistencies, as this calculation method can effectively eliminate differences between cells.

[0061] like Figure 3 As shown, taking two target cells as an example, T1 and T2 are the moments when the two target cells reach the corresponding target points. The target point SOC values of the two target cells when they reach the target points are both 60%. During the charging process, T2 is the moment when the latest of the two target cells reaches the corresponding target point, that is, T2 is the calibration point during charging. During the discharging process, T1 is the moment when the latest of the two target cells reaches the corresponding target point, that is, T1 is the calibration point during discharging. The capacity change between T1 and T2 That is, the capacity change from the corresponding target point to the calibration point.

[0062] like Figure 3 As shown, the multiple target cells include a first target cell and a second target cell. The first target cell and the second target cell may have inconsistent charging and discharging behaviors during use due to differences in internal impedance, aging, temperature changes, etc. The first target cell is the cell that first reaches the charge cutoff voltage among the multiple cells under the battery pack charging condition, that is, the cell reaches a fully charged state before other cells during the charging process. The charge cutoff voltage may refer to the maximum allowable voltage of the cell. Exceeding this voltage may cause damage to the battery or safety hazards. Therefore, when the cell reaches this voltage, charging should be stopped to prevent overcharging.

[0063] In some embodiments, the second target cell is the cell that reaches the discharge cutoff voltage first among the multiple cells in the battery pack under discharge conditions. This means that this cell depletes its charge earlier than the other cells during discharge. The discharge cutoff voltage may be the lowest allowable voltage for the cell; further discharge may damage the battery or shorten its lifespan. Therefore, when the cell reaches this voltage, discharge should be stopped to prevent overdischarge.

[0064] In some embodiments, since each cell in the battery pack performs inconsistently during the charge and discharge process, monitoring and calibrating the SOC value of the battery pack is an important part of ensuring safe and efficient operation of the battery. Under charging conditions, the first target cell that reaches the charge cut-off voltage first may stop charging prematurely while other cells continue to charge. In this case, the battery management system can calibrate the SOC value in a timely manner to avoid affecting the charging efficiency of the entire battery pack due to premature fullness of a single cell. Under discharging conditions, the second target cell that reaches the discharge cut-off voltage first may stop discharging prematurely while other cells still have remaining power. The calibration process of the SOC value can avoid affecting the overall performance of the battery pack due to premature depletion of power in a single cell.

[0065] In some embodiments, as Figure 3 As shown, under the charging condition, the SOC value of the first target cell is the sum of the target point SOC value of the first target cell and the first SOC ratio. The first SOC ratio is the ratio of the first capacity change to the current capacity of the first target cell. The first capacity change is the capacity change of the first target cell from the corresponding target point to the calibration point. This change reflects the actual charging capacity of the cell during the charging process. The specific calculation formula is as follows: ; in, is the SOC value of the first target cell, is the target point SOC value of the first target cell, is the first capacity change, is the current capacity of the first target battery cell.

[0066] In some embodiments, the SOC value of the second target cell is the target point SOC value of the second target cell at the corresponding target point. Since this cell is specifically designed for discharge conditions, its SOC value already reflects its accurate state of charge when it reaches the target point. Therefore, this target point SOC value can be directly used as the SOC value.

[0067] In some embodiments, as Figure 3As shown, under the discharge condition, the SOC value of the second target cell is the difference between the target point SOC value of the second target cell and the second SOC ratio. The second SOC ratio is the ratio of the second capacity change to the current capacity of the second target cell. The second capacity change is the capacity change of the second target cell from the corresponding target point to the calibration point. This change reflects the actual discharge capacity of the cell during the discharge process. The specific calculation formula is as follows: ; in, is the SOC value of the second target cell, is the target point SOC value of the second target cell, is the second capacity change, is the current capacity of the second target battery cell.

[0068] In some embodiments, the SOC value of the first target cell is the target point SOC value of the first target cell at the corresponding target point. Since this cell is specifically designed for charging conditions, its SOC value already reflects its accurate state of charge when it reaches the target point. Therefore, this target point SOC value can be directly used as the SOC value.

[0069] In general, accurately calculating the SOC values of the first and second target cells effectively reflects the actual state of the battery pack during charging and discharging. In particular, in applications such as electric vehicles and energy storage systems, ensuring the accurate SOC value of each cell can significantly improve the overall performance, safety, and lifespan of the battery pack.

[0070] In some embodiments, calibrating the SOC value of the battery pack according to a functional relationship includes: determining a first SOC weight of the first target battery cell and a second SOC weight of the second target battery cell according to the functional relationship. The first SOC weight reflects the degree of influence of the first target battery cell in the overall battery pack. Through the least recursive squares method, the system will analyze historical SOC data and update the weight of the first target battery cell in the SOC estimation to better represent its state. Similar to the first SOC weight, the second SOC weight represents the degree of influence of the second target battery cell in the overall battery pack. The least recursive squares method can automatically adjust this weight each time new SOC data arrives.

[0071] In some embodiments, the SOC value of the battery pack is obtained according to the SOC value and the first SOC weight of the first target battery cell and the SOC value and the second SOC weight of the second target battery cell. The specific formula is as follows: ; in, is the first SOC weight, is the second SOC weight, is the SOC value of the first target cell, is the SOC value of the second target battery cell.

[0072] In summary, by using the least recursive squares method, the SOC value and weight of the target cell can be updated at any time to reflect the latest changes in the cell status. By considering the different statuses and historical data of multiple cells, the SOC value of the battery pack can be estimated more accurately. Furthermore, the weights can be automatically adjusted according to different operating conditions and environmental changes, enhancing the system's adaptability.

[0073] In some embodiments, under full charge or full discharge conditions, the SOH (State of Health) value of the battery pack is obtained based on the SOC value of the battery pack and the capacity variation of the battery pack from the calibration point to full charge or full discharge. Taking the full charge condition as an example, the specific calculation formula is as follows: ; SOH represents the health status of the battery pack. To evaluate SOH, it can be calculated when the battery pack reaches the full charge or discharge cut-off voltage. This is because the battery's performance and capacity at this time can more clearly reflect its health status. Represents the capacity change of the battery pack from the calibration point to full charge, Indicates the SOC value of the battery pack. In the above formula, The remaining SOC represents the theoretical remaining capacity required to fully charge the battery pack from its current SOC. This value reflects how much charge the battery pack can still accept in its current state. This calculation helps determine the remaining effective capacity of the battery pack and more accurately assess its health status.

[0074] In some embodiments, the calibration method of the battery pack SOC value also includes obtaining the capacity increment of the first target battery cell from the corresponding target point to the charging cutoff under a fully charged condition, obtaining the SOC value of the first target battery cell based on the capacity increment and the target point SOC value of the first target battery cell, and updating the current capacity of the first target battery cell to the SOC value of the first target battery cell.

[0075] Specifically, under full charge conditions, the capacity increment curve of the first target cell is used to capture the target point, record the time T3, and record the capacity increment from the target point to the end of charging. , according to the capacity increment The SOC value of the first target cell is obtained by adding the target point SOC value of the first target cell. The specific calculation formula is as follows: ; in, is the SOC value of the first target cell, is the capacity increment of the first target cell from the corresponding target valley point to the charging cutoff, is the target point SOC value of the first target battery cell.

[0076] In some embodiments, the initial SOC value of the first target battery cell during the charging process can also be obtained through the SOC value of the first target battery cell. The specific formula is as follows: ; in, is the initial SOC of the first target cell charging process, is the SOC value of the first target battery cell, and Q is the battery cell capacity (fixed value).

[0077] In some embodiments, the calibration method of the battery pack SOC value also includes obtaining the capacity reduction of the second target battery cell from the start of discharge to the target point corresponding to the second target battery cell under a full discharge condition, obtaining the SOC value of the second target battery cell based on the capacity reduction and the target point SOC value of the second target battery cell, and updating the current capacity of the second target battery cell to the SOC value of the second target battery cell.

[0078] Specifically, under full discharge conditions, the capacity increment curve of the second target cell is used to capture the target point, record the time T4, and record the capacity reduction from the start of discharge to the target point corresponding to the second target cell. , according to capacity reduction The SOC value of the second target cell is obtained by combining the target point SOC value of the second target cell. The specific calculation formula is as follows: ; in, is the SOC value of the second target cell, is the capacity reduction from the start of discharge to the target point corresponding to the second target cell, is the target point SOC value of the second target battery cell.

[0079] In some embodiments, the initial SOC of the second target battery cell discharge process is 0.

[0080] In some embodiments, the target cell is determined based on stored historical battery data. This historical battery data is recorded information related to the battery pack's operating status and cell performance, and may include, but is not limited to, the maximum voltage cell number, minimum voltage cell number, maximum voltage cell capacity, minimum voltage cell capacity, and the overall capacity of the battery pack. By analyzing this historical data, performance differences between cells can be identified, and cells that have a greater impact on the battery pack's SOC changes can be selected as target cells, thereby more accurately reflecting the battery pack's SOC value.

[0081] Figure 4 FIG. 1 is an overall flow chart of a method for calibrating a battery pack SOC value according to an embodiment of the present invention. Figure 4 As shown, the overall process of the battery pack SOC value calibration method includes steps S10-S18.

[0082] S10, when the system is powered on, read the previous historical data fields of the battery pack from the storage, including information such as the maximum voltage cell number, the minimum voltage cell number, the maximum voltage cell capacity, the minimum voltage cell capacity and the battery pack capacity.

[0083] S11 , during the charging and discharging process, identifying and grabbing target points of the first target battery cell and the second target battery cell.

[0084] S12, obtaining target point SOC values of the first target battery cell and the second target battery cell when they reach the target point.

[0085] S13, taking the time when the latest of the multiple target battery cells reaches the corresponding target point as the calibration point, and obtaining the capacity change of each target battery cell from the corresponding target point to the calibration point.

[0086] S14 , obtaining the SOC value of the target battery cell at the calibration point according to the target point SOC value and the capacity change of each target battery cell.

[0087] S15 , obtaining an SOC value of the battery pack by using a least recursive squares method according to the SOC values of the multiple target battery cells.

[0088] S16 , obtaining the SOH value of the battery pack according to the SOC value of the battery pack and the capacity variation of the battery pack from the calibration point to full charge or full discharge.

[0089] S17, under the full charge condition, obtain the capacity increment of the first target battery cell from the corresponding target point to the charging cutoff, obtain the SOC value of the first target battery cell according to the capacity increment and the target point SOC value of the first target battery cell, and update the current SOC value of the first target battery cell to the SOC value of the first target battery cell.

[0090] S18, under the full discharge condition, obtain the capacity reduction of the second target battery cell from the start of discharge to the target corresponding to the second target battery cell, obtain the SOC value of the second target battery cell according to the capacity reduction and the target point SOC value of the second target battery cell, and update the current SOC value of the second target battery cell to the SOC value of the second target battery cell.

[0091] In general, the SOC values of multiple target cells are used to calibrate the SOC value of the entire battery pack. By comprehensively considering the SOC value of each cell, the present invention effectively addresses the differences between cells and ensures the accuracy and consistency of the SOC at the level of the entire battery pack. This calibration process effectively reduces the SOC estimation error caused by cell inconsistency, thereby improving the calibration accuracy of the SOC value of the entire battery pack.

[0092] Reference below Figure 5 A device for calibrating the SOC value of a battery pack according to an embodiment of the present invention is described.

[0093] Figure 5 FIG. 1 is a block diagram of a device for calibrating a battery pack SOC value according to an embodiment of the present invention. Figure 5 As shown, the battery pack SOC value calibration device 1 includes: a memory 12 and at least one processor 11.

[0094] In some embodiments, the at least one processor 11 may be one processor 11, or may be two processors 11, three processors 11, five processors 11, or other multiple processors 11. These processors 11 may be various types of general-purpose or special-purpose processors, such as a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), and the like.

[0095] In some embodiments, the memory 12 may be a random access memory (RAM), a read-only memory (ROM), or a flash memory to ensure fast access and persistent storage of programs during runtime.

[0096] In some embodiments, the battery pack SOC value calibration device 1 is an electronic device that has the functions of monitoring, calculating and calibrating the battery pack SOC and can be widely used in electric vehicles, battery energy storage systems and other fields.

[0097] In some embodiments, the memory 12 is communicatively connected to at least one processor 11, and the memory 12 stores a computer program that can be executed by at least one processor 11. When at least one processor 11 executes the computer program, the battery pack SOC value calibration method of the above embodiment can be implemented.

[0098] According to an embodiment of the present invention, a battery pack SOC calibration device 1 includes at least one processor 11 executing a computer program implementing the battery pack SOC calibration method described in the above embodiments. The device obtains the SOC values of multiple target cells in the battery pack and, based on these SOC values, establishes a functional relationship between the cell SOC values and the battery pack SOC value. This relationship effectively maps the relationship between the state of individual cells and the overall state of the battery pack. This functional relationship enables accurate calibration of the battery pack SOC value. In this process, the SOC value of each target cell represents the state of that cell, while the battery pack SOC value is a comprehensive reflection of the states of multiple cells. By establishing a functional relationship between the cell SOC value and the battery pack SOC value, the present invention comprehensively considers the SOC performance of each cell and optimizes the calibration of the overall battery pack SOC value. Because different cells in a battery pack may have different performance, relying solely on the SOC value of a single cell is prone to introducing errors. By establishing this functional relationship, SOC estimation errors caused by performance differences between cells can be effectively reduced, thereby improving the calibration accuracy of the overall battery pack SOC value.

[0099] The present invention also provides a non-volatile readable storage medium having a computer program stored thereon. When the computer program is executed by the processor 11, the battery pack SOC value calibration method described in the above embodiment is implemented. The specific implementation process of the battery pack SOC value calibration method can be referred to the description of the above embodiment.

[0100] The computer-readable storage medium of the embodiments of the present invention may include, but is not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other optical or magnetic storage media, which are not listed here one by one.

[0101] According to the non-volatile readable storage medium of an embodiment of the present invention, by adopting the battery pack SOC value calibration method described in the above embodiment, it is possible to effectively address the performance differences between battery cells, reduce the SOC estimation error caused by battery cell inconsistency, and thus improve the calibration accuracy of the SOC value of the entire battery pack.

[0102] Reference below Figure 6 An electric energy device according to an embodiment of the present invention is described.

[0103] Figure 6 is a block diagram of an electric energy device according to an embodiment of the present invention, such as Figure 6 As shown, the electric energy device 100 includes: a battery pack 2 and the battery pack SOC calibration device 1 described in the above embodiment.

[0104] Battery pack 2 comprises multiple cells connected in series or parallel to store and release electrical energy. A series connection increases the voltage of battery pack 2, while a parallel connection increases its current capability and capacity. This design enables the battery pack to meet diverse energy needs and application scenarios.

[0105] In some embodiments, the battery pack SOC calibration device 1 is used to calibrate the SOC value and SOH value of the battery pack 2 and calibrate the capacity of a target cell among multiple cells. The specific calibration method is as described above and will not be detailed here.

[0106] According to an embodiment of the present invention, the electric energy device 100 employs the aforementioned battery pack SOC value calibration device 1. Based on the obtained SOC values of multiple target cells in the battery pack, a functional relationship can be established between the cell SOC value and the battery pack SOC value. This relationship effectively maps the relationship between the state of an individual cell and the overall state of the battery pack. This functional relationship enables precise calibration of the battery pack SOC value. In this process, the SOC value of each target cell represents the state of that cell, while the battery pack SOC value is a comprehensive reflection of the states of multiple cells. Furthermore, the present invention can calibrate the capacity of target cells within multiple cells based on this functional relationship, thereby ensuring the consistency of the capacity of each cell in the battery pack 2. Furthermore, the present invention can calibrate the SOH value of the battery pack 2 based on the overall SOC value of the battery pack 2. Because different cells in the battery pack 2 may have different performance, relying solely on the SOC value of a single cell can easily introduce errors. By establishing a functional relationship between the battery cell SOC value and the battery pack SOC value, not only can the calibration of the battery pack SOC value be optimized, but the SOC estimation error caused by battery cell performance differences can also be effectively reduced, thereby improving the calibration accuracy of the SOC value and SOH value of the entire battery pack.

[0107] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "example," "specific example," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0108] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A method for calibrating the SOC value of a battery pack, characterized in that: include: Obtain the SOC values of multiple target cells in the battery pack; Obtaining a functional relationship between the SOC values of the battery cells in the battery pack and the SOC value of the battery pack according to the SOC values of the multiple target battery cells; The SOC value of the battery pack is calibrated according to the functional relationship.

2. The calibration method according to claim 1, wherein: Obtaining a functional relationship between the SOC values of the battery cells in the battery pack and the SOC value of the battery pack according to the SOC values of the multiple target battery cells includes: A functional relationship between the SOC values of the battery cells in the battery pack and the SOC value of the battery pack is obtained by using a least recursive square method according to the SOC values of the multiple target battery cells.

3. The calibration method according to claim 1 or 2, characterized in that: Each of the target battery cells has a corresponding capacity increment curve, and the SOC value of the target battery cell is obtained based on data of a target point on the corresponding capacity increment curve, where the target point includes at least one of a peak point and a trough point.

4. The calibration method according to claim 3, wherein: The target point is a target trough point; The target valley point is located on a curve segment of the capacity increment curve corresponding to a voltage platform jump region of the target battery cell.

5. The calibration method according to claim 4, characterized in that: The capacity increment curve of the target battery cell includes a first valley point and a second valley point, the voltage value corresponding to the first valley point is smaller than the voltage value corresponding to the second valley point, and the target valley point is the second valley point.

6. The calibration method according to claim 3, wherein: Obtain the SOC values of multiple target cells in the battery pack, including: Obtaining a target point SOC value of each target battery cell when the target point is reached; Taking the moment when the latest of the target cells reaches the corresponding target point as a calibration point, obtaining a capacity change of each target cell from the corresponding target point to the calibration point; The SOC value of the target battery cell at the calibration point is obtained according to the target point SOC value of each target battery cell and the capacity change.

7. The calibration method according to claim 6, characterized in that: The multiple target battery cells include a first target battery cell and a second target battery cell. The first target battery cell is the battery cell that first reaches the charge cut-off voltage among the multiple battery cells under the charging condition of the battery pack, and the second target battery cell is the battery cell that first reaches the discharge cut-off voltage among the multiple battery cells under the discharging condition of the battery pack.

8. The calibration method according to claim 7, characterized in that: In charging condition, The SOC value of the first target battery cell is the sum of the target point SOC value of the first target battery cell and a first SOC ratio, the first SOC ratio is the ratio of the first capacity change to the current capacity of the first target battery cell, and the first capacity change is the capacity change of the first target battery cell from the corresponding target point to the calibration point; The SOC value of the second target battery cell is a target point SOC value of the second target battery cell at the corresponding target point.

9. The calibration method according to claim 7, wherein: Under discharge conditions, The SOC value of the first target battery cell is a target point SOC value of the first target battery cell at the corresponding target point; The SOC value of the second target battery cell is the difference between the target point SOC value of the second target battery cell and the second SOC ratio, the second SOC ratio is the ratio of the second capacity change to the current capacity of the second target battery cell, and the second capacity change is the capacity change of the second target battery cell from the corresponding target point to the calibration point.

10. The calibration method according to claim 7, wherein: Calibrating the SOC value of the battery pack according to the functional relationship includes: Determine a first SOC weight of the first target battery cell and a second SOC weight of the second target battery cell according to the functional relationship; The SOC value of the battery pack is obtained according to the SOC value of the first target battery cell and the first SOC weight, and the SOC value of the second target battery cell and the second SOC weight.

11. The calibration method according to claim 6, wherein: The calibration method further comprises: Under full charge or full discharge conditions, The SOH value of the battery pack is obtained according to the SOC value of the battery pack and the capacity change of the battery pack from the calibration point to full charge or full discharge.

12. The calibration method according to claim 8, wherein: The calibration method further comprises: Under full charge condition, Obtaining a capacity increment of the first target battery cell from a corresponding target point to a charging cutoff; Obtaining an SOC value of the first target battery cell according to the capacity increment and a target point SOC value of the first target battery cell; The current capacity of the first target battery cell is updated to the SOC value of the first target battery cell.

13. The calibration method according to claim 9, characterized in that: The calibration method further comprises: Under full discharge conditions, Obtaining a capacity reduction of the second target battery cell from the start of discharge to a target point corresponding to the second target battery cell; Obtaining an SOC value of the second target battery cell according to the capacity reduction and a target point SOC value of the second target battery cell; The current capacity of the second target battery cell is updated to the SOC value of the second target battery cell.

14. The calibration method according to claim 1 or 2, characterized in that: The target battery cell is determined based on stored battery history data.

15. A battery pack SOC value calibration device, characterized in that: include: at least one processor; a memory communicatively coupled to the at least one processor; The memory stores a computer program that can be executed by the at least one processor, and when the at least one processor executes the computer program, the battery pack SOC value calibration method according to any one of claims 1 to 14 is implemented.

16. A non-volatile readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed, the battery pack SOC value calibration method according to any one of claims 1 to 14 is implemented.

17. An electric energy device, characterized in that: include: A battery pack and a calibration device for the battery pack SOC value as described in claim 15, wherein the battery pack includes a plurality of battery cells connected in series or in parallel, and the calibration device is used to calibrate the SOC value and SOH value of the battery pack and calibrate the capacity of a target battery cell among the plurality of battery cells.

Images