Method and device for determining capacity of single cell, and medium
By constructing a voltage-charge model and using Pearson correlation coefficients to screen cells for testing, and combining bilinear interpolation to calculate the capacity of a single cell, the problems of accuracy and operational complexity in single cell capacity measurement are solved, achieving efficient and accurate capacity determination.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-28
- Publication Date
- 2026-03-13
AI Technical Summary
Existing technologies cannot accurately and non-invasively measure the capacity of individual battery cells. Furthermore, traditional methods are complex to operate, have limited practicality, ignore the differential capacity decay of battery cells, and are susceptible to noise interference in current integration, leading to a decrease in measurement accuracy.
A voltage-charge model was constructed using a reference cell, the cell to be tested was screened using the Pearson correlation coefficient, and the charge throughput was determined using bilinear interpolation. The capacity of a single cell was calculated based on the actual charge throughput.
It achieves high-precision, non-invasive determination of individual cell capacity, simplifies the operation process, improves data utilization and early fault warning capabilities, and reduces the impact of noise interference.
Smart Images
Figure CN121656891A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of battery capacity calculation, and in particular to a method, device and medium for determining the capacity of a single battery cell. Background Technology
[0002] In commercial and industrial energy storage systems, which consist of battery packs composed of multiple cells connected in series, accurately knowing the actual capacity of each individual cell is crucial for battery health assessment, balance management, lifespan prediction, and safety.
[0003] The core pain points of existing methods for measuring the actual capacity of individual battery cells are reflected in four aspects: First, individual battery cells cannot be disassembled for independent charge and discharge capacity measurement during battery pack operation; second, traditional capacity estimation methods rely on complete full charge and discharge cycles, which limits their practicality; third, some battery management systems assume that the cell capacity is consistent and only use voltage differences for balancing, ignoring the serious impact of cell capacity degradation on the overall usable capacity and lifespan of the battery pack; and fourth, the direct current integration method is susceptible to interference from sensor noise, sampling frequency, and accumulated errors, and the measurement accuracy will continue to decline after long-term use.
[0004] In view of the above-mentioned technologies, finding a non-invasive and highly accurate method to determine the actual capacity of each individual battery cell is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0005] The purpose of this application is to provide a method, device, and medium for determining the capacity of a single battery cell. This addresses the problems in existing technologies where the measurement of the actual capacity of a single battery cell is complex, practically limited, fails to consider the differential capacity decay of cells, and is susceptible to interference during current integration, leading to a continuous decrease in measurement accuracy.
[0006] To address the aforementioned technical problems, this application provides a method for determining the capacity of a single battery cell, comprising: Voltage-charge models at different temperatures are constructed based on the reference voltage change and charge throughput of the reference cell in different charge-discharge segments at different temperatures; where the reference cell is the single cell with the lowest degradation rate among all cells in the battery pack. Within the same charge / discharge segment, obtain the Pearson correlation coefficients of each individual cell in the battery pack (excluding the reference cell) with the reference cell, and select the individual cells with Pearson correlation coefficients higher than a set threshold as the individual cells to be tested. Bilinear interpolation was used to determine the voltage change of the individual battery cell under test and the actual charge throughput corresponding to the actual temperature in the voltage-charge model. The capacity of a single battery cell is determined based on the actual charge throughput.
[0007] Preferably, obtaining the reference voltage change and charge throughput of the reference cell during the charge / discharge cycle includes: Obtain the current parameters of the battery pack in the current charge / discharge segment; Obtain the start and end times corresponding to the current charge / discharge segment; Obtain the starting reference voltage of the reference cell at the start time and the ending reference voltage at the end time; The charge throughput is obtained by integrating the current parameters over the start and end times. The difference between the starting reference voltage and the ending reference voltage is calculated to obtain the change in reference voltage.
[0008] Preferably, obtaining the Pearson correlation coefficients between each individual cell in the battery pack (excluding the reference cell) and the reference cell includes: Obtain the voltage sequence corresponding to each individual cell in the current charge / discharge segment; Obtain the reference voltage sequence corresponding to the reference cell in the current charge / discharge segment; The Pearson correlation coefficients for the voltage series and the reference voltage series are determined based on the Pearson correlation coefficient formula.
[0009] Preferably, the expression for the Pearson correlation coefficient formula is as follows: ; in, The Pearson correlation coefficient is the value corresponding to the i-th individual cell. For covariance; This represents the voltage sequence corresponding to the i-th individual cell. This refers to the reference voltage sequence corresponding to the reference cell. Let be the standard deviation corresponding to the i-th individual cell; This is the standard deviation corresponding to the reference battery cell.
[0010] Preferably, a bilinear interpolation method is used to determine the voltage change corresponding to the individual battery cell under test and the actual charge throughput corresponding to the actual temperature in the voltage-charge model, including: Obtain the voltage change and the voltage charge data points of the actual temperature in the corresponding voltage charge model for the single cell under test. In the voltage-charge model, determine the first and second data points adjacent to the voltage-charge data points; Obtain the first and second temperatures adjacent to the actual temperature. Bilinear interpolation is used to determine the actual charge throughput corresponding to the first and second data points at the first and second temperatures.
[0011] Preferably, bilinear interpolation is used to determine the actual charge throughput corresponding to the first data point and the second data point at the first temperature and the second temperature, including: Obtain the first voltage-charge curve corresponding to the first data point and the second voltage-charge parameter curve corresponding to the second data point; Obtain the first charge throughput and the second charge throughput corresponding to the first voltage-charge curves at the first temperature and the second temperature, respectively. The actual temperature, the first charge throughput, the second charge throughput, and the first target charge throughput corresponding to the first and second temperatures are determined using a first interpolation method. The third and fourth charge throughputs corresponding to the second voltage-charge curves at the first and second temperatures are obtained respectively. The actual temperature, the third charge throughput, the fourth charge throughput, and the second target charge throughput corresponding to the first and second temperatures are determined using a second interpolation method. The corresponding actual charge throughput is determined based on the first target charge throughput and the second target charge throughput.
[0012] Preferably, the expression for the first interpolation method is: ; The expression for the second interpolation method is: ; in, The primary target is charge throughput; This represents the first charge throughput. This is the second charge throughput; This is the actual temperature; The first temperature; The second temperature; The second target is charge throughput; This represents the third charge throughput. This represents the fourth charge throughput.
[0013] Preferably, determining the corresponding single-cell capacity based on the actual charge throughput includes: Obtain the change in charge state of the single cell under test in the current charge / discharge segment; The quotient of the actual charge throughput and the change in charge state is taken as the cell capacity corresponding to the cell under test.
[0014] On the other hand, this application also provides an electronic device, including a memory for storing computer programs; A processor is used to execute computer programs to implement the steps of the above-described method for determining the capacity of a single battery cell.
[0015] On the other hand, this application also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the above-described method for determining the capacity of a single battery cell.
[0016] This application provides a method for determining the capacity of a single battery cell. The method includes: constructing a voltage-charge model at different temperatures based on the reference voltage change and charge throughput of a reference cell in different charge-discharge segments at different temperatures; wherein the reference cell is the single cell with the lowest degradation rate among the single cells in the battery pack; obtaining the Pearson correlation coefficients of each single cell in the battery pack (excluding the reference cell) with the reference cell within the same charge-discharge segment, and selecting single cells with Pearson correlation coefficients higher than a set threshold as the single cells to be tested; using bilinear interpolation to determine the voltage change and the actual charge throughput corresponding to the actual temperature in the voltage-charge model for the single cell to be tested; and determining the corresponding single cell capacity based on the actual charge throughput. In other words, this application can use any charge / discharge segment during the measurement process, without the need for a complete charge / discharge cycle, making it simple to operate, highly practical, and improving data utilization and update frequency; furthermore, it selects individual cells whose Pearson correlation coefficient with the reference cell is greater than a set threshold as the individual cells to be tested, effectively eliminating noise and interference, ensuring the quality of input data, and also improving early fault warning capabilities; and this application uses charge-voltage correlation data to eliminate the influence of current integration error, improving the accuracy of individual cell capacity calculation. Attached Figure Description
[0017] To more clearly illustrate the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 A flowchart illustrating a method for determining the capacity of a single battery cell, as provided in an embodiment of this application; Figure 2 A complete flowchart of a method for determining the capacity of a single battery cell provided in an embodiment of this application; Figure 3 A structural diagram of an electronic device provided in another embodiment of this application. Detailed Implementation
[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this application.
[0020] The core of this application is to provide a method, device, and medium for determining the capacity of a single battery cell.
[0021] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0022] Figure 1 A flowchart of a method for determining the capacity of a single battery cell provided in this application embodiment is shown below. Figure 1 As shown, it includes the following steps: S10: Based on the reference voltage change and charge throughput of the reference cell in different charge and discharge segments at different temperatures, a voltage-charge model is constructed for different temperatures; where the reference cell is the cell with the lowest degradation rate among all cells in the battery pack.
[0023] In a specific embodiment, the battery pack includes multiple individual cells connected in series. Based on the performance of the multiple individual cells, the individual cell with the lowest degradation rate is determined and then used as a reference cell among the multiple individual cells in the battery pack.
[0024] Because different temperatures have varying effects on individual battery cells, and because the charging and discharging process of an individual battery cell is not a linear or quadratic function, the relationships between relevant parameters within the individual battery cell differ at different temperatures and during different charge / discharge cycles. To ensure the accuracy of subsequent calculations, it is necessary to construct corresponding voltage-charge models for different charge / discharge cycles at different temperatures. These voltage-charge models primarily characterize the relationship between voltage changes and charge throughput.
[0025] As a preferred embodiment, obtaining the reference voltage change and charge throughput of the reference cell in a charge / discharge segment includes: obtaining the current parameters of the battery pack in the current charge / discharge segment; obtaining the start time and end time corresponding to the current charge / discharge segment; obtaining the start reference voltage of the reference cell at the start time and the end reference voltage at the end time; integrating the current parameters over the start and end times to obtain the charge throughput; and calculating the difference between the start and end reference voltages to obtain the reference voltage change.
[0026] It is understandable that the relationships between relevant parameters within individual cells differ at different temperatures and in different charge / discharge segments, corresponding to different voltage-charge models. Therefore, any segment can be selected during the specific calculation. Specifically, the current parameters of the battery pack in the currently selected charge / discharge segment, as well as the start and end times of that segment, are obtained. Since the multiple individual cells within the battery pack are connected in series, and the reference cell is also included, the charge throughput obtained by integrating the current parameters over the start and end times represents the total charge throughput of the battery pack in that charge / discharge segment, and can also characterize the charge throughput of the reference cell. The reference voltage change mainly refers to the voltage change of the reference cell in that charge / discharge segment. Therefore, it can be obtained from the starting reference voltage at the start time and the ending reference voltage at the end time; that is, the difference between the starting and ending reference voltages is used as the reference voltage change.
[0027] It is not difficult to understand that the essence of the reference voltage change is the voltage change. It is only used here to describe the voltage change of the reference cell, so that it can be distinguished later.
[0028] S11: Obtain the Pearson correlation coefficients of each individual cell in the battery pack (excluding the reference cell) with the reference cell within the same charge / discharge segment, and designate the individual cells with Pearson correlation coefficients higher than a set threshold as the individual cells to be tested.
[0029] In specific embodiments, the relationships between relevant parameters within the battery cell differ at different temperatures and during different stages of charging and discharging. To ensure the accuracy of subsequent calculations, it is necessary to select a charging / discharging segment at the current moment and determine the reference battery cell and the remaining individual battery cells within this segment. In other words, it is necessary to determine the reference battery cell and the remaining individual battery cells within the same charging / discharging segment.
[0030] In this charge / discharge segment, the Pearson correlation coefficients between the remaining individual cells and the reference cell are obtained. A higher Pearson correlation coefficient means a higher correlation between the reference cell and the current individual cell. This can also be understood as a Pearson correlation coefficient closer to 1 indicating a more similar shape and trend in the voltage curves of the reference cell and the current individual cell. When the Pearson correlation coefficient is higher than a set threshold (e.g., 0.97), the segment at that threshold is considered a "high-consistency segment" and can be used for capacity calculation, effectively filtering out noise, equalization circuit operation, and other interference.
[0031] The concept is straightforward: individual cells with a Pearson correlation coefficient higher than a set threshold are considered for testing. However, it's important to clarify that cells with a correlation coefficient lower than the set threshold are not included in subsequent calculations. This doesn't mean these cells will never be calculated; rather, due to the current environment (temperature and charge / discharge cycle), these cells' Pearson correlation coefficients may be lower than the set threshold due to their inherent characteristics. However, in other environments, their Pearson correlation coefficients might exceed the threshold, thus requiring further calculations in those conditions.
[0032] In one preferred embodiment, the method of obtaining the Pearson correlation coefficients of each individual cell in the battery pack (excluding the reference cell) with respect to the reference cell includes: obtaining the voltage sequence corresponding to each individual cell in the current charge / discharge segment; obtaining the reference voltage sequence corresponding to the reference cell in the current charge / discharge segment; and determining the Pearson correlation coefficients corresponding to the voltage sequence and the reference voltage sequence based on the Pearson correlation coefficient formula.
[0033] The formula for the Pearson correlation coefficient is as follows: ; in, The Pearson correlation coefficient is the value corresponding to the i-th individual cell. For covariance; This represents the voltage sequence corresponding to the i-th individual cell. This refers to the reference voltage sequence corresponding to the reference cell. Let be the standard deviation corresponding to the i-th individual cell; This is the standard deviation corresponding to the reference battery cell.
[0034] In other words, the voltage sequence corresponding to each individual cell in the current charge / discharge segment is obtained. and the reference voltage sequence corresponding to the reference cell. Among them, voltage sequence It consists of the voltages of a single battery cell at various points in time during the current charge / discharge cycle; while the reference voltage sequence... It is constructed by referencing the voltage of the battery cell at various time points within the current charge / discharge cycle. The voltage sequence is ultimately determined based on the Pearson correlation coefficient formula. and reference voltage sequence The corresponding Pearson correlation coefficient is used, and each individual cell with a Pearson correlation coefficient higher than a set threshold is selected as the individual cell to be tested.
[0035] S12: Using bilinear interpolation, determine the voltage change of the individual cell under test and the actual charge throughput corresponding to the actual temperature in the voltage-charge model.
[0036] In specific embodiments, since the use of resources is considered when constructing voltage-charge models, corresponding voltage-charge models are constructed for each temperature range. That is, a voltage-charge model is constructed at 20°C, a voltage-charge model is constructed at 30°C, a voltage-charge model is constructed at 40°C, and so on. However, in actual applications, the specific temperature may be 25°C. Therefore, interpolation is required to determine the corresponding actual charge throughput.
[0037] In one preferred embodiment, a bilinear interpolation method is used to determine the voltage change and actual charge throughput corresponding to the actual temperature in the voltage-charge model of the single cell under test. This includes: acquiring voltage-charge data points corresponding to the voltage change and actual temperature in the corresponding voltage-charge model of the single cell under test; determining a first data point and a second data point adjacent to the voltage-charge data points in the voltage-charge model; acquiring a first temperature and a second temperature adjacent to the actual temperature; acquiring a first voltage-charge curve corresponding to the first data point and a second voltage-charge parameter curve corresponding to the second data point; acquiring the first charge throughput and the second charge throughput corresponding to the first voltage-charge curve at the first temperature and the second temperature, respectively; determining the actual temperature, the first charge throughput, the second charge throughput, and the first target charge throughput corresponding to the first and second temperatures using a first interpolation method; acquiring the third charge throughput and the fourth charge throughput corresponding to the second voltage-charge curve at the first temperature and the second temperature, respectively; determining the actual temperature, the third charge throughput, the fourth charge throughput, and the second target charge throughput corresponding to the first and second temperatures using a second interpolation method; and determining the corresponding actual charge throughput based on the first target charge throughput and the second target charge throughput.
[0038] The expression for the first interpolation method is: ; The expression for the second interpolation method is: ; in, The primary target is charge throughput; This represents the first charge throughput. This is the second charge throughput; This is the actual temperature; The first temperature; The second temperature; The second target is charge throughput; This represents the third charge throughput. This represents the fourth charge throughput.
[0039] In other words, determining the voltage change and actual charge throughput corresponding to the actual temperature in the voltage-charge model using bilinear interpolation involves the following nine steps: 1. According to Calculate the voltage change of the individual battery cell under test, and obtain the corresponding voltage and charge data points from the corresponding voltage and charge model. .in, This refers to the change in voltage. This is the voltage corresponding to the termination time in this charge / discharge segment; This is the voltage corresponding to the start time in this charge / discharge segment.
[0040] 2. Determine the voltage charge data points in the voltage charge model. Adjacent first data point Second data point .in The voltage represented by the first data point (which can also be understood as the corresponding first voltage-charge curve). The charge throughput is represented by the first data point; The voltage represented by the second data point (which can also be understood as the corresponding second voltage-charge curve) This represents the charge throughput as characterized by the second data point. And... .
[0041] 3. Obtain the actual temperature Adjacent first temperature Second temperature .
[0042] 4. Obtain the first data point The corresponding first voltage-charge curve and the second data point The corresponding second voltage-charge parameter curve .
[0043] 5. Obtain the first temperature respectively Second temperature First voltage-charge curve The corresponding first charge throughput Second charge throughput .
[0044] 6. Use the first interpolation method ( Determine the actual temperature First charge throughput Second charge throughput First temperature Second temperature The corresponding first target charge throughput That is to say, in On this line, the first temperature Second temperature The corresponding first charge throughput Second charge throughput Interpolation yields the actual temperature. The corresponding first target charge throughput .
[0045] 7. Obtain the first temperature respectively Second temperature Lower second voltage-charge curve The corresponding third charge throughput and fourth charge throughput .
[0046] 8. Use the second interpolation method ( Determine the actual temperature Third charge throughput Fourth charge throughput First temperature Second temperature The corresponding second target charge throughput That is to say, in On this line, the first temperature Second temperature The corresponding third charge throughput and fourth charge throughput Interpolation yields the actual temperature. The corresponding second target charge throughput .
[0047] 9. Based on the first target charge throughput Second target charge throughput Determine the corresponding actual charge throughput, that is, in Perform a linear interpolation in the dimension ( ) to obtain the corresponding actual charge throughput .
[0048] S13: Determine the corresponding single cell capacity based on the actual charge throughput.
[0049] In a specific embodiment, the change in charge state of the single cell under test in the current charge / discharge segment is first obtained. Then the actual charge throughput With charge state change The quotient is used as the single cell capacity corresponding to the cell under test. In addition, the capacity of a single battery cell... You can also take the final average value by measuring multiple times.
[0050] Therefore, it can be seen that, Figure 2 As shown, the complete process of determining the capacity of a single battery cell includes the following steps: S20: Begin.
[0051] S21: Voltage sequence acquisition and current data acquisition.
[0052] S22: Determine the start and end times.
[0053] S23: Determine the charge throughput corresponding to the reference cell.
[0054] S24: Determine the corresponding voltage and charge data points of the individual battery cell under test in the corresponding voltage and charge model. .
[0055] S25: Obtain the Pearson correlation coefficients between each individual cell in the battery pack (excluding the reference cell) and the reference cell within the same charge / discharge segment. .
[0056] S26: Judgment .
[0057] S27: If so, If not, proceed to step S31.
[0058] S28: .
[0059] S29: .
[0060] S30: .
[0061] S31: End.
[0062] Since steps S20-S31 are a summary of the above embodiments, they will not be described in detail here.
[0063] Furthermore, this application provides a specific implementation method: 1. The Battery Management System (BMS) records the voltage and total current of all individual cells at 50ms intervals during each charge and discharge cycle.
[0064] 2. When a continuous charge / discharge cycle with a current greater than 0.1C is detected, and the SOC (State of Charge / remaining battery capacity) changes by more than 5%, the calculation process is triggered.
[0065] 3. The system has a built-in healthy reference cell and its voltage and charge model.
[0066] 4. Calculate the Pearson correlation coefficient between the voltage of each individual cell and the reference cell voltage in this segment. .like If so, then that data segment will be retained.
[0067] 5. For the voltage change of the individual battery cell under test, the actual charge throughput is obtained by finding adjacent points in the corresponding voltage-charge model and performing bilinear interpolation. .
[0068] 6. The charge throughput obtained in this round The capacity value of the tested individual cell is updated by weighting the historical values. .
[0069] 7. The data points from this segment are also added to the voltage-charge model, and the model evolves over time.
[0070] Therefore, the method for determining the capacity of a single battery cell provided in this application has the following advantages: 1. No need for a complete loop: It can be calculated using any fragment of data from daily operation, which greatly improves data utilization and update frequency.
[0071] 2. Improve the robustness of capacity calculation: By using the Pearson correlation coefficient to screen highly consistent data, noise and interference are effectively eliminated, ensuring the quality of input data and improving the early fault warning capability.
[0072] 3. Non-invasive: Utilizes existing sensor data from the BMS without increasing hardware costs.
[0073] 4. Strong noise immunity: Current integration error is common to all cells, but this application weakens its impact by comparing voltage curves.
[0074] 5. Automatic calibration: This method can run continuously, track the capacity decay of each individual cell in real time, and achieve online automatic calibration.
[0075] Figure 3 A structural diagram of an electronic device provided in another embodiment of this application, such as... Figure 2 As shown, the electronic device includes: a memory 20 for storing computer programs; The processor 21 is used to execute a computer program to implement the steps of the single cell capacity determination method mentioned in the above embodiments.
[0076] The electronic devices provided in this embodiment may include, but are not limited to, smartphones, tablets, laptops, or desktop computers.
[0077] The processor 21 may include one or more processing cores, such as a quad-core processor or an octa-core processor. The processor 21 may be implemented using at least one of the following hardware forms: Digital Signal Processor (DSP), Field-Programmable Gate Array (FPGA), or Programmable Logic Array (PLA). The processor 21 may also include a main processor and a coprocessor. The main processor, also known as the Central Processing Unit (CPU), is used to process data in the wake-up state; the coprocessor is a low-power processor used to process data in the standby state. In some embodiments, the processor 21 may integrate a Graphics Processing Unit (GPU), which is responsible for rendering and drawing the content to be displayed on the screen. In some embodiments, the processor 21 may also include an Artificial Intelligence (AI) processor, which is used to handle computational operations related to machine learning.
[0078] The memory 20 may include one or more computer-readable storage media, which may be non-transitory. The memory 20 may also include high-speed random access memory and non-volatile memory, such as one or more disk storage devices or flash memory devices. In this embodiment, the memory 20 is used to store at least the following computer program 201, which, after being loaded and executed by the processor 21, is capable of implementing the relevant steps of the single-cell capacity determination method disclosed in any of the foregoing embodiments. In addition, the resources stored in the memory 20 may also include an operating system 202 and data 203, and the storage method may be temporary storage or permanent storage. The operating system 202 may include Windows, Unix, Linux, etc.
[0079] In some embodiments, the electronic device may further include a display screen 22, an input / output interface 23, a communication interface 24, a power supply 25, and a communication bus 26.
[0080] Those skilled in the art will understand that Figure 3 The structures shown do not constitute a limitation on electronic devices and may include more or fewer components than those shown.
[0081] The electronic device provided in this application includes a memory and a processor. When the processor executes the program stored in the memory, it can implement the above-described method for determining the capacity of a single battery cell and has the same beneficial effects.
[0082] Finally, this application also provides an embodiment corresponding to a computer-readable storage medium. The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps described in the above method embodiments.
[0083] It is understood that if the methods in the above embodiments are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and executes all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.
[0084] The foregoing provides a detailed description of a method, apparatus, and medium for determining the capacity of a single battery cell. The various embodiments in the specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.
[0085] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
Claims
1. A method for determining the capacity of a single battery cell, characterized in that, include: A voltage-charge model at different temperatures is constructed based on the reference voltage variation and charge throughput of the reference cell in different charge-discharge segments at different temperatures. The reference cell is the individual cell with the lowest degradation rate among all individual cells in the battery pack; Within the same charge / discharge segment, obtain the Pearson correlation coefficients of each individual cell in the battery pack (excluding the reference cell) with the reference cell, and designate each individual cell with a Pearson correlation coefficient higher than a set threshold as the individual cell to be tested. Bilinear interpolation is used to determine the voltage change of the single cell under test and the actual charge throughput corresponding to the actual temperature in the voltage-charge model. The corresponding single-cell capacity is determined based on the actual charge throughput.
2. The method for determining the capacity of a single battery cell according to claim 1, characterized in that, Obtaining the reference voltage change and charge throughput of the reference cell during the charge / discharge cycle includes: Obtain the current parameters of the battery pack in the current charge / discharge segment; Obtain the start and end times corresponding to the current charge / discharge segment; Obtain the starting reference voltage of the reference cell at the starting time and the ending reference voltage at the ending time; The charge throughput is obtained by integrating the current parameters at the start time and the end time. The difference between the starting reference voltage and the ending reference voltage is calculated to obtain the change in the reference voltage.
3. The method for determining the capacity of a single battery cell according to claim 1, characterized in that, Obtaining the Pearson correlation coefficients of each individual cell in the battery pack (excluding the reference cell) with the reference cell, including: Obtain the voltage sequence corresponding to each individual cell in the current charge / discharge segment; Obtain the reference voltage sequence corresponding to the reference cell in the current charge / discharge segment; The Pearson correlation coefficients for the voltage series and the reference voltage series are determined based on the Pearson correlation coefficient formula.
4. The method for determining the capacity of a single battery cell according to claim 3, characterized in that, The expression for the Pearson correlation coefficient formula is as follows: ； in, The Pearson correlation coefficient is the value corresponding to the i-th individual battery cell. For covariance; The voltage sequence corresponding to the i-th individual battery cell; The reference voltage sequence corresponding to the reference cell; Let be the standard deviation corresponding to the i-th individual cell; This represents the standard deviation corresponding to the reference cell.
5. The method for determining the capacity of a single battery cell according to claim 1, characterized in that, The method employs bilinear interpolation to determine the voltage change corresponding to the tested individual cell and the actual charge throughput corresponding to the actual temperature in the voltage-charge model, including: Obtain the voltage change corresponding to the single cell under test and the voltage charge data points of the actual temperature in the corresponding voltage charge model; In the voltage-charge model, determine the first and second data points adjacent to the voltage-charge data points; Obtain the first and second temperatures adjacent to the actual temperature; The actual charge throughput corresponding to the first data point and the second data point at the first temperature and the second temperature is determined by using the bilinear interpolation method.
6. The method for determining the capacity of a single battery cell according to claim 5, characterized in that, The step of determining the actual charge throughput corresponding to the first data point and the second data point at the first temperature and the second temperature using the bilinear interpolation method includes: Obtain the first voltage-charge curve corresponding to the first data point and the second voltage-charge parameter curve corresponding to the second data point; Obtain the first charge throughput and the second charge throughput corresponding to the first voltage-charge curve at the first temperature and the second temperature, respectively; The actual temperature, the first charge throughput, the second charge throughput, and the first target charge throughput corresponding to the first temperature and the second temperature are determined using a first interpolation method. The third and fourth charge throughputs corresponding to the second voltage-charge curves at the first and second temperatures are obtained, respectively. The actual temperature, the third charge throughput, the fourth charge throughput, and the second target charge throughput corresponding to the first temperature and the second temperature are determined using a second interpolation method. The actual charge throughput is determined based on the first target charge throughput and the second target charge throughput.
7. The method for determining the capacity of a single battery cell according to claim 6, characterized in that, The expression for the first interpolation method is: ； The expression for the second interpolation method is: ； in, The first target charge throughput; This is the first charge throughput; This is the second charge throughput; The actual temperature; The first temperature; The second temperature; The second target charge throughput; The third charge throughput; This refers to the fourth charge throughput.
8. The method for determining the capacity of a single battery cell according to any one of claims 1-7, characterized in that, Determining the corresponding single-cell capacity based on the actual charge throughput includes: Obtain the change in charge state of the single cell under test in the current charge / discharge segment; The quotient of the actual charge throughput and the charge state change is taken as the cell capacity corresponding to the cell under test.
9. An electronic device, characterized in that, Includes memory used to store computer programs; A processor, configured to execute the computer program to implement the steps of the single-cell capacity determination method as described in any one of claims 1 to 8.
10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the single-cell capacity determination method as described in any one of claims 1 to 8.