Method and device for evaluating difference between single batteries of battery pack

Abstract

The invention discloses a method and device for evaluating the difference between single batteries of a battery pack, and relates to the technical field of batteries, and the method comprises the steps: obtaining the operation data of a target battery pack, the operation data being the charging data or discharging data of each single battery in the target battery pack; determining a reference single battery from a plurality of single batteries in the target battery pack according to the operation data; and evaluating the difference of the single batteries of the target battery pack according to the voltage change curve of the reference single battery to obtain a target evaluation result. Through the method and the device, the problem of relatively low accuracy of difference evaluation caused by evaluating the difference of the single batteries by measuring the terminal voltage or the open-circuit voltage of each single battery in the lithium battery pack in a standing state in the prior art is solved.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a method and apparatus for evaluating the differences between individual cells in a battery pack. Background Technology

[0002] In the management and application of lithium-ion battery packs, ensuring the consistency of individual cells within the pack is crucial for improving overall performance and safety. A commonly used method in related technologies is to assess the differences between individual cells by measuring their terminal voltage or open-circuit voltage under static conditions. However, this static assessment method has significant limitations; it only reflects voltage differences at a specific point in time, ignoring the battery's actual performance during dynamic charge and discharge processes, resulting in relatively low accuracy in difference assessment.

[0003] There is currently no effective solution to the problem that the accuracy of individual cell differences assessment is relatively low when measuring the terminal voltage or open-circuit voltage of each cell in a lithium battery pack under static conditions. Summary of the Invention

[0004] The main objective of this application is to provide a method and apparatus for evaluating the differences between individual cells in a battery pack, in order to solve the problem that the accuracy of the difference evaluation is relatively low when evaluating the differences between individual cells in a lithium battery pack by measuring the terminal voltage or open circuit voltage of each individual cell in a static state.

[0005] To achieve the above objectives, according to one aspect of this application, a method for evaluating the differences between individual cells in a battery pack is provided. The method includes: acquiring operational data of a target battery pack, wherein the operational data is charging or discharging data of each individual cell in the target battery pack; determining a reference individual cell from a plurality of individual cells in the target battery pack based on the operational data; and evaluating the differences between the individual cells in the target battery pack based on the voltage variation curve of the reference individual cell to obtain a target evaluation result.

[0006] Further, determining the reference cell from multiple individual cells in the target battery pack based on the operating data includes: obtaining the voltage change curve of each individual cell from the operating data; determining the time information of each individual cell reaching the cutoff voltage based on the voltage change curve; and determining the reference cell from the multiple individual cells based on the time information.

[0007] Further, based on the voltage change curve of the reference single cell, the differences between the individual cells of the target battery pack are evaluated to obtain the target evaluation result, including: evaluating the capacity difference of the individual cells of the target battery pack based on the voltage change curve of the reference single cell, and obtaining a capacity difference evaluation result; evaluating the health status difference of the individual cells of the target battery pack based on the capacity difference evaluation result, and obtaining a health status difference evaluation result; and obtaining the target evaluation result based on the capacity difference evaluation result and the health status difference evaluation result.

[0008] Further, based on the voltage change curve of the reference single cell, the differences between the individual cells of the target battery pack are evaluated to obtain the target evaluation result. This includes: obtaining a first voltage change curve of the reference single cell at a first current value and obtaining a second voltage change curve of each target single cell at the first current value, wherein the target single cell is the single cell in the target battery pack other than the reference single cell; determining whether the similarity between the first voltage change curve and the second voltage change curve is greater than or equal to a preset threshold; if the similarity is greater than or equal to the preset threshold, the differences between the individual cells of the target battery pack are evaluated based on the first voltage change curve and the second voltage change curve to obtain the target evaluation result.

[0009] Further, obtaining the second voltage change curve of each target cell at the first current value includes: performing temperature correction on the first initial voltage change curve of each target cell at the first current value based on the temperature data of the reference cell to obtain a first correction curve; performing internal resistance correction on the first correction curve of each target cell based on the incremental capacity curve of the reference cell to obtain a second correction curve; and performing capacity correction on the second correction curve of each target cell to obtain the second voltage change curve.

[0010] Further, the temperature correction of the first initial voltage change curve of each target cell at the first current value based on the temperature data of the reference cell includes: obtaining the first average temperature value of the reference cell and the second average temperature value of each target cell based on the operating data; calculating the difference between the first average temperature value and the second average temperature value to obtain a target difference; and performing temperature correction on the first initial voltage change curve based on the target difference and the entropy thermal coefficient of the target battery pack to obtain the first correction curve.

[0011] Further, the process of correcting the internal resistance of the first correction curve of each target cell based on the incremental capacity curve of the reference cell to obtain the second correction curve includes: obtaining the incremental capacity curve corresponding to each target cell based on the first correction curve; determining a first voltage value based on the incremental capacity curve of the reference cell, and determining a second voltage value corresponding to each target cell based on the incremental capacity curve of each target cell; and correcting the internal resistance of the first correction curve based on the difference between the first voltage value and the second voltage value to obtain the second correction curve.

[0012] Further, the second correction curve of each target cell is modified for capacity to obtain the second voltage change curve, which includes: obtaining the open-circuit voltage and state of charge relationship curve corresponding to each target cell; and modifying the second correction curve of each target cell for capacity based on the open-circuit voltage and state of charge relationship curve to obtain the second voltage change curve.

[0013] Further, the second correction curve for each target cell is modified to obtain the second voltage change curve by: obtaining the incremental capacity curve corresponding to each target cell based on the first correction curve; and modifying the second correction curve to obtain the second voltage change curve based on the cell capacity value corresponding to the peak value in the incremental capacity curve corresponding to each target cell.

[0014] Furthermore, after determining whether the similarity between the first voltage change curve and the second voltage change curve is greater than or equal to a preset threshold, the method further includes: if the similarity is less than the preset threshold, repeating the steps of obtaining the third voltage change curve of the reference single cell at the second current value and obtaining the fourth voltage change curve of each target single cell at the second current value, until the similarity between the current voltage change curve of the reference single cell and the current voltage change curve of the target single cell is greater than or equal to the preset threshold; evaluating the differences between the single cells of the target battery pack based on the current voltage change curve of the reference single cell and the current voltage change curve of the target single cell to obtain the target evaluation result.

[0015] Furthermore, the method further includes: obtaining a current adjustment range; adjusting the first current value according to the current adjustment range to obtain the second current value.

[0016] To achieve the above objectives, according to another aspect of this application, a device for evaluating the differences between individual cells in a battery pack is provided. The device includes: a first acquisition unit for acquiring operational data of a target battery pack, wherein the operational data is charging or discharging data of each individual cell in the target battery pack; a determination unit for determining a reference individual cell from a plurality of individual cells in the target battery pack based on the operational data; and a first evaluation unit for evaluating the differences between the individual cells in the target battery pack based on the voltage change curve of the reference individual cell, thereby obtaining a target evaluation result.

[0017] Further, the determining unit includes: a first acquisition subunit, used to acquire the voltage change curve of each individual cell from the operating data; a first determining subunit, used to determine the time information of each individual cell reaching the cutoff voltage based on the voltage change curve; and a second determining subunit, used to determine the reference individual cell from the plurality of individual cells based on the time information.

[0018] Further, the first evaluation unit includes: a first evaluation subunit, used to evaluate the capacity difference of the individual cells in the target battery pack based on the voltage change curve of the reference individual cell, and obtain a capacity difference evaluation result; a second evaluation subunit, used to evaluate the health status difference of the individual cells in the target battery pack based on the capacity difference evaluation result, and obtain a health status difference evaluation result; and a third determination subunit, used to obtain the target evaluation result based on the capacity difference evaluation result and the health status difference evaluation result.

[0019] Further, the first evaluation unit includes: a second acquisition subunit, configured to acquire a first voltage change curve of the reference single cell at a first current value and acquire a second voltage change curve of each target single cell at the first current value, wherein the target single cell is a single cell in the target battery pack other than the reference single cell; a judgment subunit, configured to determine whether the similarity between the first voltage change curve and the second voltage change curve is greater than or equal to a preset threshold; and an evaluation subunit, configured to evaluate the differences between the single cells of the target battery pack based on the first voltage change curve and the second voltage change curve if the similarity is greater than or equal to the preset threshold, thereby obtaining the target evaluation result.

[0020] Further, the second acquisition subunit includes: a first correction module, used to perform temperature correction on the first initial voltage change curve of each target single cell at the first current value based on the temperature data of the reference single cell, to obtain a first correction curve; a second correction module, used to perform internal resistance correction on the first correction curve of each target single cell based on the incremental capacity curve of the reference single cell, to obtain a second correction curve; and a third correction module, used to perform capacity correction on the second correction curve of each target single cell, to obtain the second voltage change curve.

[0021] Further, the first correction module includes: a first acquisition submodule, used to acquire a first average temperature value of the reference single cell and a second average temperature value of each target single cell based on the operating data; a calculation submodule, used to calculate the difference between the first average temperature value and the second average temperature value to obtain a target difference; and a first correction submodule, used to perform temperature correction on the first initial voltage change curve based on the target difference and the entropy thermal coefficient of the target battery pack to obtain the first correction curve.

[0022] Further, the second correction module includes: a first processing submodule, used to obtain the incremental capacity curve corresponding to each target single cell based on the first correction curve; a determination submodule, used to determine a first voltage value based on the incremental capacity curve of the reference single cell, and to determine a second voltage value corresponding to each target single cell based on the incremental capacity curve corresponding to each target single cell; and a second correction submodule, used to perform internal resistance correction on the first correction curve based on the difference between the first voltage value and the second voltage value to obtain the second correction curve.

[0023] Furthermore, the third correction module includes: a second acquisition submodule, used to acquire the open-circuit voltage and state of charge relationship curve corresponding to each target single cell; and a third correction submodule, used to perform capacity correction on the second correction curve of each target single cell based on the open-circuit voltage and state of charge relationship curve to obtain the second voltage change curve.

[0024] Furthermore, the third correction module includes: a second processing submodule, used to obtain the incremental capacity curve corresponding to each target single cell based on the first correction curve; and a fourth correction submodule, used to perform capacity correction on the second correction curve based on the battery capacity value corresponding to the peak value in the incremental capacity curve corresponding to each target single cell, to obtain the second voltage change curve.

[0025] Furthermore, the device further includes: an execution unit, configured to, after determining whether the similarity between the first voltage change curve and the second voltage change curve is greater than or equal to a preset threshold, if the similarity is less than the preset threshold, repeatedly execute the steps of obtaining the third voltage change curve of the reference single cell at the second current value and obtaining the fourth voltage change curve of each target single cell at the second current value, until the similarity between the current voltage change curve of the reference single cell and the current voltage change curve of the target single cell is greater than or equal to the preset threshold; and a second evaluation unit, configured to evaluate the differences between the single cells of the target battery pack based on the current voltage change curve of the reference single cell and the current voltage change curve of the target single cell, and obtain the target evaluation result.

[0026] Furthermore, the device further includes: a second acquisition unit for acquiring a current adjustment range; and an adjustment unit for adjusting the first current value according to the current adjustment range to obtain the second current value.

[0027] According to another aspect of the present invention, an electronic device is also provided, comprising: a memory storing an executable program; and a processor for running the program, wherein the program executes the single-cell difference evaluation method for a battery pack as described above.

[0028] According to another aspect of the present invention, a computer-readable storage medium is also provided, the storage medium storing a program, wherein, when the program is running, the device where the storage medium is located executes the single-cell difference evaluation method of the battery pack described above.

[0029] According to another aspect of the present invention, a computer program product is also provided, including a computer program or instructions, which, when executed by a processor, implement the single-cell difference evaluation method for a battery pack according to any one of the above embodiments.

[0030] In this embodiment, the following steps are adopted: obtaining the operating data of the target battery pack, wherein the operating data is the charging data or discharging data of each individual cell in the target battery pack; determining a reference cell from multiple individual cells in the target battery pack based on the operating data; evaluating the differences between individual cells in the target battery pack based on the voltage change curve of the reference cell, and obtaining the target evaluation result. This solves the technical problem in related technologies where the accuracy of difference evaluation is relatively low when evaluating the differences between individual cells by measuring the terminal voltage or open circuit voltage of each individual cell in the lithium battery pack under static conditions.

[0031] In this approach, operational data of the target battery pack during charging and discharging is collected. Based on this data, a single cell is selected as a benchmark cell. Direct comparison with the benchmark cell accurately identifies differences in other cells, avoiding the uncertainties caused by voltage self-discharge differences between cells in static evaluation. Using the voltage variation curve of the benchmark cell, the performance of each cell in the target battery pack is evaluated to obtain the target evaluation result. Through the collection and analysis of dynamic data, and comparison with the benchmark cell, the consistency and trends of battery performance under actual operating conditions can be better reflected. This allows for a comprehensive assessment of the health status and differences of individual cells, achieving the technical effect of improving the accuracy of difference assessment. Attached Figure Description

[0032] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0033] Figure 1 A hardware block diagram of a computer terminal for implementing a method for evaluating the differences between individual cells in a battery pack is shown.

[0034] Figure 2 This is a flowchart of a method for evaluating the differences between individual cells in a battery pack according to an embodiment of this application;

[0035] Figure 3 This is a schematic diagram of the method for evaluating the differences between individual cells in a battery pack according to the embodiments of this application. Figure 1 ;

[0036] Figure 4 This is a schematic diagram of the method for evaluating the differences between individual cells in a battery pack according to the embodiments of this application. Figure 2 ;

[0037] Figure 5 This is a schematic diagram of the method for evaluating the differences between individual cells in a battery pack according to the embodiments of this application. Figure 3 ;

[0038] Figure 6 This is a schematic diagram of the method for evaluating the differences between individual cells in a battery pack according to the embodiments of this application. Figure 4 ;

[0039] Figure 7 This is a schematic diagram of the method for evaluating the differences between individual cells in a battery pack according to the embodiments of this application. Figure 5 ;

[0040] Figure 8 This is a schematic diagram of the method for evaluating the differences between individual cells in a battery pack according to the embodiments of this application. Figure 6 ;

[0041] Figure 9 This is a schematic diagram of the method for evaluating the differences between individual cells in a battery pack according to the embodiments of this application. Figure 7 ;

[0042] Figure 10 This is a schematic diagram of the method for evaluating the differences between individual cells in a battery pack according to the embodiments of this application. Figure 8 ;

[0043] Figure 11 This is a schematic diagram of the method for evaluating the differences between individual cells in a battery pack according to the embodiments of this application. Figure 9 ;

[0044] Figure 12 This is a schematic diagram of the method for evaluating the differences between individual cells in a battery pack according to the embodiments of this application. Figure 10 ;

[0045] Figure 13 This is a schematic diagram of the method for evaluating the differences between individual cells in a battery pack according to the embodiments of this application. Figure 10 one;

[0046] Figure 14 This is a schematic diagram of a battery pack individual cell difference evaluation device provided according to an embodiment of this application;

[0047] Figure 15 This is a structural block diagram of an electronic device according to an embodiment of this application. Detailed Implementation

[0048] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0049] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0050] It should be noted that the information collected in this application (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for display, data used for analysis, etc.) are information and data authorized by the user or fully authorized by all parties. Furthermore, the collection, storage, use, processing, transmission, provision, disclosure, and application of this data all comply with relevant laws, regulations, and standards, necessary confidentiality measures have been taken, and they do not violate public order and good morals. Corresponding access points are provided for users to choose to authorize or refuse. For example, interfaces are set up between this system and relevant users or organizations, providing users with corresponding access points to choose to agree to or refuse automated decision-making results; if the user chooses to refuse, the process proceeds to the expert decision-making stage.

[0051] Example 1

[0052] According to an embodiment of this application, a method embodiment for evaluating the differences between individual cells in a battery pack is also provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0053] The method embodiment provided in Embodiment 1 of this application can be executed on a mobile terminal, computer terminal, or similar computing device. Figure 1 A hardware block diagram of a computer terminal (or mobile device) for implementing a method for evaluating the differences between individual cells in a battery pack is shown. Figure 1As shown, the computer terminal 10 (or mobile device) may include one or more processors 102 (shown as 102a, 102b, ..., 102n in the figure) 102 (processor 102 may include, but is not limited to, a microprocessor MCU or a programmable logic device FPGA, etc.), a memory 104 for storing data, and a transmission device 106 for communication functions. In addition, it may also include: a display, an input / output interface (I / O interface), a universal serial bus (USB) port (which may be included as one of the ports of a BUS bus), a network interface, a power supply, and / or a camera. Those skilled in the art will understand that... Figure 1 The structure shown is for illustrative purposes only and does not limit the structure of the aforementioned electronic device. For example, computer terminal 10 may also include... Figure 1 The more or fewer components shown, or having the same Figure 1 The different configurations shown.

[0054] It should be noted that the aforementioned one or more processors 102 and / or other data processing circuits are generally referred to herein as "data processing circuits". These data processing circuits may be embodied, in whole or in part, in software, hardware, firmware, or any other combination thereof. Furthermore, the data processing circuits may be a single, independent processing module, or may be integrated, in whole or in part, into any other element within the computer terminal 10 (or mobile device). As involved in the embodiments of this application, the data processing circuits serve as a processor control mechanism (e.g., selection of a variable resistor termination path connected to an interface).

[0055] The memory 104 can be used to store software programs and modules for application software, such as the program instructions / data storage device corresponding to the battery pack single-cell difference evaluation method in this embodiment. The processor 102 executes various functional applications and data processing by running the software programs and modules stored in the memory 104, thereby realizing the aforementioned battery pack single-cell difference evaluation method. The memory 104 may include high-speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory 104 may further include memory remotely located relative to the processor 102, and these remote memories can be connected to the computer terminal 10 via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0056] The transmission device 106 is used to receive or send data via a network. Specific examples of the network described above may include a wireless network provided by the communication provider of the computer terminal 10. In one example, the transmission device 106 includes a Network Interface Controller (NIC), which can connect to other network devices via a base station to communicate with the Internet. In another example, the transmission device 106 may be a Radio Frequency (RF) module, used for wireless communication with the Internet.

[0057] The display may be a touchscreen liquid crystal display (LCD) that allows the user to interact with the user interface of the computer terminal 10 (or mobile device).

[0058] Under the aforementioned operating environment, this application provides the following: Figure 2 The method for evaluating the differences between individual cells in the battery pack is shown. Figure 2 This is a flowchart of a method for evaluating the differences between individual cells in a battery pack according to Embodiment 1 of this application. The method for evaluating the differences between individual cells in this battery pack includes:

[0059] Step S201: Obtain the operating data of the target battery pack, wherein the operating data is the charging data or discharging data of each individual cell in the target battery pack.

[0060] Optionally, the operating data of the lithium battery pack can be collected from continuous discharge from 100% SOC to 0% SOC, or from charging from 0% SOC to 100% SOC. It should be noted that the operating data includes, but is not limited to, the voltage, temperature, charge and discharge current, SOC (state of charge), and SOH (state of health) of each individual battery in the pack.

[0061] Step S202: Based on the operating data, determine the reference cell from multiple individual cells in the target battery pack.

[0062] Optionally, before selecting a reference cell, the collected operational data can be preprocessed, such as by removing outliers or noise, to ensure data quality. The selection criteria for the reference cell can be determined based on requirements; for example, based on operational data, the first cell to reach the charge or discharge cutoff voltage can be identified and designated as the reference cell.

[0063] Step S203: Based on the voltage change curve of the reference single cell, evaluate the differences between the single cells of the target battery pack to obtain the target evaluation result.

[0064] Optionally, the capacity difference between individual cells in the target battery pack is evaluated based on the voltage change curve of the reference cell to obtain the capacity difference. Then, the health status difference between individual cells in the target battery pack can be evaluated based on the capacity difference to obtain the final target evaluation result.

[0065] In some embodiments, the similarity of the voltage curves of a reference cell and a selected cell is evaluated. The charge and discharge current is gradually adjusted until the similarity between the voltage curve of the selected cell and the reference curve exceeds a set threshold. Then, the current difference between the selected cell and the reference cell is integrated to obtain the capacity difference of the selected cell relative to the reference cell. Based on the capacity difference and historical data from battery cycling, the health status differences of individual cells are assessed. Through comprehensive evaluation based on the reference cell, the dynamic performance differences of individual cells within the target battery pack can be accurately captured and quantified. The evaluation results can be used for various aspects of battery pack equalization control, thermal management, fault diagnosis, and lifespan prediction, providing a basis for decision-making regarding the efficient operation and maintenance of the battery system.

[0066] In summary, by collecting operational data of the target battery pack during charging and discharging, and selecting a single cell as a benchmark cell based on this data, the differences between other cells can be accurately identified through direct comparison with the benchmark cell, avoiding the uncertainties caused by differences in voltage self-discharge between cells in static evaluation. Using the voltage variation curve of the benchmark cell, the performance of each cell in the target battery pack is evaluated to obtain the target evaluation results. Through the collection and analysis of dynamic data, and comparison with the benchmark cell, the consistency and trend of battery performance under actual operating conditions can be better reflected, thereby enabling a comprehensive assessment of the health status and differences of individual cells, achieving the technical effect of improving the accuracy of difference assessment.

[0067] Optionally, in the battery pack individual cell difference evaluation method provided in this application embodiment, determining the reference individual cell from multiple individual cells in the target battery pack based on operating data includes: obtaining the voltage change curve of each individual cell from the operating data; determining the time information of each individual cell reaching the cutoff voltage based on the voltage change curve; and determining the reference individual cell from multiple individual cells based on the time information.

[0068] In an optional embodiment, the voltage variation curve of each individual battery cell is extracted from the collected operational data. It should be noted that the voltage variation curve can be either the voltage change over time during the charging and discharging process of an individual battery cell, or the voltage change over capacity during the charging and discharging process, i.e., the VC curve, where C represents the state of charge (SOC).

[0069] For each voltage change curve, identify and mark the point where the individual cell reaches its cutoff voltage. This point is a key indicator for evaluating the performance of the individual cell, reflecting its response speed and health status. Record the time from the start of charging / discharging to reaching the cutoff voltage for each individual cell. Compare the time information for all individual cells to reach the cutoff voltage, identify the individual cell with the shortest time, and determine it as the benchmark individual cell.

[0070] In an alternative embodiment, such as Figure 3 The charging curves (voltage versus time curves) of multiple individual cells are shown, for cell-1, cell-2, and cell-3. From Figure 3 As can be seen from the data, Cell-1 is the first cell to reach the cutoff voltage; therefore, Cell-1 is selected as the reference cell.

[0071] Based on operational data, the most representative individual units are automatically selected as benchmarks, avoiding the uncertainty and bias caused by subjective selection and improving the accuracy of the evaluation results.

[0072] Optionally, in the battery pack individual cell difference evaluation method provided in this application embodiment, the difference between individual cells of the target battery pack is evaluated based on the voltage change curve of the reference individual cell to obtain the target evaluation result, including: evaluating the capacity difference of individual cells of the target battery pack based on the voltage change curve of the reference individual cell to obtain the capacity difference evaluation result; evaluating the health status difference of individual cells of the target battery pack based on the capacity difference evaluation result to obtain the health status difference evaluation result; and obtaining the target evaluation result based on the capacity difference evaluation result and the health status difference evaluation result.

[0073] In an optional embodiment, the individual cells in the target battery pack are evaluated for differences by comparison with a reference individual cell, thereby obtaining evaluation results regarding differences in capacity and health status.

[0074] In some embodiments, the capacity difference between a selected individual cell and a reference individual cell can be calculated using the voltage variation curves of the individual cells in the target battery pack, thus obtaining the aforementioned capacity difference assessment result. For example, by comparing the voltage variation curve of a selected individual cell in the target battery pack with the voltage variation curve of a determined reference individual cell, the voltage offset of the selected individual cell relative to the reference individual cell during the charge and discharge process can be calculated based on the curve comparison results. The capacity difference between the selected individual cell and the reference individual cell can then be calculated by using the voltage offset and the known battery parameters.

[0075] In some embodiments, based on the capacity difference information obtained from the aforementioned assessment, the differences in the state of health (SOH, i.e., the health status of the battery) of individual cells are further analyzed. For example, the differences in the state of health (SOH) of individual cells are obtained based on the standard capacity of the individual cells in the target battery pack and the capacity difference.

[0076] In addition to real-time SOH difference assessment, the health status of individual cells can be predicted by long-term tracking of the SOH difference trend between selected individual cells and benchmark individual cells, providing forward-looking guidance for adjusting battery management strategies.

[0077] By analyzing the voltage variation curves of a benchmark cell, the capacity differences among selected cells in the target battery pack can be precisely assessed, thus more accurately reflecting the inconsistencies within the battery pack. Based on the capacity difference assessment results, the health status differences of individual cells can be further evaluated, enabling the prediction of changes in the health status of individual cells, timely maintenance measures, extension of battery pack lifespan, and reduction of maintenance costs.

[0078] Optionally, in the battery pack individual cell difference evaluation method provided in this application embodiment, the difference between individual cells of the target battery pack is evaluated based on the voltage change curve of the reference individual cell to obtain the target evaluation result. This includes: obtaining a first voltage change curve of the reference individual cell under a first current value and obtaining a second voltage change curve of each target individual cell under a first current value, wherein the target individual cell is the individual cell in the target battery pack other than the reference individual cell; determining whether the similarity between the first voltage change curve and the second voltage change curve is greater than or equal to a preset threshold; if the similarity is greater than or equal to the preset threshold, the difference between individual cells of the target battery pack is evaluated based on the first voltage change curve and the second voltage change curve to obtain the target evaluation result.

[0079] In an optional embodiment, the voltage change curve of a reference cell at a preset first current value is obtained, i.e., the first voltage change curve mentioned above. The voltage change curves of each cell in the target battery pack, excluding the reference cell, at the same first current value are obtained, i.e., the second voltage change curves mentioned above.

[0080] To quantify the difference or similarity between two curves, it is necessary to evaluate the similarity between a proportionally scaled individual cell time-voltage curve and a reference individual cell time-voltage curve. Curve similarity evaluation is common in data analysis, and many methods exist, such as cosine similarity, Euclidean distance, and Dynamic Time Warping (DTW). This application does not impose detailed limitations on these methods. For example, a curve similarity evaluation algorithm (such as DTW) can be used to evaluate the similarity of the overlapping portion of the reference individual cell time-voltage curve and the selected individual cell time-voltage curve. The calculated similarity is then compared with a preset threshold. The preset threshold can be set according to the battery pack's performance requirements and consistency standards.

[0081] If the similarity is greater than or equal to the preset threshold, it indicates that the voltage change trend of the target cell is basically consistent with that of the reference cell at the first current value, and its specific performance indicators such as capacity difference and health status difference can be further analyzed.

[0082] Without requiring independent testing of each individual cell, the differences between all individual cells in the target battery pack can be quickly screened and evaluated by comparing with a benchmark cell and limiting preset thresholds, greatly improving evaluation efficiency.

[0083] Optionally, in the battery pack single-cell difference evaluation method provided in this application embodiment, after determining whether the similarity between the first voltage change curve and the second voltage change curve is greater than or equal to a preset threshold, the method further includes: if the similarity is less than the preset threshold, repeating the steps of obtaining the third voltage change curve of the reference single cell under the second current value and obtaining the fourth voltage change curve of each target single cell under the second current value, until the similarity between the current voltage change curve of the reference single cell and the current voltage change curve of the target single cell is greater than or equal to the preset threshold; evaluating the differences between the single cells of the target battery pack based on the current voltage change curve of the reference single cell and the current voltage change curve of the target single cell to obtain the target evaluation result.

[0084] In an optional embodiment, if the similarity is less than a preset threshold, the current magnitude is gradually changed, the charge / discharge current is adjusted to a second current value, and the reference single cell is recharged and discharged using the adjusted second current value to obtain a third voltage change curve. Each target single cell in the target battery pack (each cell other than the reference single cell) is charged and discharged at the same second current value, and their respective fourth voltage change curves are obtained.

[0085] Optionally, in the battery pack single cell difference evaluation method provided in the embodiments of this application, the second current value can be obtained in the following manner: obtain the current adjustment range; adjust the first current value according to the current adjustment range to obtain the second current value.

[0086] In an optional embodiment, a current adjustment range is pre-defined based on the battery pack's rated parameters and safe operating boundaries. This range may include a minimum adjustment current value and a maximum adjustment current value, used to limit the upper and lower limits of subsequent adjustments, ensuring all current adjustment operations are performed within battery safety and system controllability. During the iterative process of capacity difference identification, a first current value serves as the initial benchmark, initiating an iterative adjustment mechanism. The first current value is adjusted within the current adjustment range in preset steps (e.g., 0.05C) to obtain a second current value. By introducing explicit upper and lower limit constraints during current adjustment, physical distortion, system misjudgment, or safety risks caused by excessive current adjustment amplitude can be effectively avoided. This ensures that the algorithm can still stably, safely, and accurately output capacity difference assessment results under complex operating conditions, providing a reliable basis for battery pack balance control and health management.

[0087] After obtaining the fourth voltage change curve, the similarity between the third voltage change curve and each of the fourth voltage change curves is calculated again using a curve similarity evaluation algorithm (such as DTW dynamic time warping, Euclidean distance, etc.) to determine whether a preset threshold has been reached. If the similarity is still lower than the preset threshold at the second current value, the above process is repeated, gradually adjusting the current magnitude until the similarity between the current voltage change curve of the reference cell and the current voltage change curve of the target cell is greater than or equal to the preset threshold. Then, the individual cells of the target battery pack are evaluated for differences based on the current voltage change curve and the current voltage change curve of the target cell to obtain the target evaluation result.

[0088] In some embodiments, a similarity evaluation is performed on the overlapping portion of the reference cell time-voltage curve and the selected cell time-voltage curve. A reasonable similarity threshold is set, and the current magnitude is gradually changed. Iterative calculations are performed until the similarity between the selected battery curve and the reference cell curve is less than the set threshold, at which point the iteration process ends, and the current and the time t of the overlapping portion of the two curves are recorded. In an optional embodiment, a schematic diagram of the charging curve after iterative changes with gradually changing current magnitude is shown below. Figure 4 As shown, the charging curves include those of the Cell-1 reference battery. Figure 4 (blue curve in the image), and Cell-2 ( Figure 4 After iteration of the red curve in the image, and Cell-3 ( Figure 4The charging curve after iteration (green curve in the image). Capacity difference calculation: The difference between the iterative current Ii and the initial current Iinital is integrated over time t to obtain the capacity difference of the selected cell relative to the reference cell. The calculation formula is: ,in, This represents the capacity difference value.

[0089] In an optional embodiment, a comparison chart of the corrected charging capacity value (i.e., the corrected result) obtained through the embodiments of this application and the experimental test results is shown below. Figure 5 As shown, the experimental test results and correction results for Cell-1, Cell-2, and Cell-3 are presented. Figure 5 As can be seen, the corrected charging capacity value is basically consistent with the actual charging capacity. Therefore, the embodiments of this application can more accurately assess the capacity difference between the selected cell and the reference cell.

[0090] By using the selected current value and its corresponding time during the iteration process, and through an integral calculation formula, the capacity difference between the selected single cell and the reference single cell can be obtained. This capacity difference calculation method based on current changes during actual charging and discharging not only considers voltage changes but also integrates the current factor during charging and discharging, providing a more scientific way to evaluate capacity differences.

[0091] Optionally, in the battery pack single-cell difference evaluation method provided in this application embodiment, obtaining the second voltage change curve of each target single cell under the first current value includes: performing temperature correction on the first initial voltage change curve of each target single cell under the first current value based on the temperature data of the reference single cell to obtain a first correction curve; performing internal resistance correction on the first correction curve of each target single cell based on the incremental capacity curve of the reference single cell to obtain a second correction curve; and performing capacity correction on the second correction curve of each target single cell to obtain a second voltage change curve.

[0092] In an optional embodiment, in order to more accurately assess the differences between individual cells within the battery pack, the voltage change curve is corrected for temperature, internal resistance, and capacity.

[0093] Battery voltage characteristics are significantly affected by temperature. Higher temperatures can cause a slight decrease in battery voltage, while lower temperatures may cause an increase in voltage or a decrease in battery performance. Therefore, to eliminate the interference of temperature on the voltage change curve, temperature correction is needed for the voltage curve of the target individual cell. For example, ... Figure 6The temperature change curves of individual cells Cell-1, Cell-2, and Cell-3 within the group during charging are shown. Based on the temperature data of the reference cell, the initial voltage change curve (first initial voltage change curve) of each target cell at the first current value is adjusted to obtain the first corrected curve. For example, as shown... Figure 7 The charging curves of Cell-1, Cell-2, and Cell-3 after temperature correction are shown, with Cell-1 serving as the reference cell. This correction ensures that the voltage change curves of all individual cells are simulated under the same temperature conditions, thereby eliminating the influence of temperature factors on subsequent evaluation results.

[0094] Battery internal resistance increases with battery aging, directly impacting the voltage change curve. Higher internal resistance results in a larger voltage drop at the same current, and vice versa. Therefore, internal resistance correction aims to reflect battery performance under the same internal resistance conditions by adjusting the voltage curve. The incremental capacity curve (ICA curve) of a reference single-cell battery is used; the peak position of this curve is closely related to the battery's internal resistance and can be used to indirectly assess the battery's health. Based on the ICA curve, the internal resistance difference of the target single-cell battery is calculated, and the first correction curve is adjusted accordingly to obtain a second correction curve reflecting the elimination of the internal resistance difference.

[0095] Before batteries are assembled into packs, they are generally sorted by capacity and voltage. Cells can only be grouped if the voltage difference is within a certain range under a specific SOC. Generally, the SOC difference between individual cells within a pack is small, but the different aging states of individual cells over long-term cycling will increase the SOC difference between individual cells. The main sources of SOC difference are that some cells have a low initial SOC when charging, resulting in the loss of voltage curve data at the end of charging, or some cells have a high initial SOC when discharging, resulting in the loss of voltage curve data at the end of discharging, or the loss of voltage curve data at the end of charging and discharging. Therefore, the second correction curve of each target cell is corrected for capacity to obtain the second voltage change curve.

[0096] By revising the process, the accuracy of individual cell difference assessment can be significantly improved, ensuring that the assessment results are not affected by changes in external conditions.

[0097] Optionally, in the battery pack single-cell difference evaluation method provided in this application embodiment, the first initial voltage change curve of each target single cell under a first current value is temperature-corrected based on the temperature data of the reference single cell to obtain the first correction curve. This includes: obtaining the first average temperature value of the reference single cell and the second average temperature value of each target single cell based on the operating data; calculating the difference between the first average temperature value and the second average temperature value to obtain the target difference; and performing temperature correction on the first initial voltage change curve based on the target difference and the entropy thermal coefficient of the target battery pack to obtain the first correction curve.

[0098] In an optional embodiment, a first average temperature value (T0) of a reference cell during the charge-discharge process is extracted from the operational data. This step ensures a temperature standard for subsequent temperature correction. Similarly, a second average temperature value (Ti) is extracted from the operational data for each target cell in the target battery pack (all cells except the reference cell). This temperature value represents the average temperature state of each cell during the charge-discharge process and is used for subsequent temperature difference calculations and corrections.

[0099] Then, the average temperature difference (ΔTi = Ti - T0) between each target cell and its reference cell is calculated. This difference reflects the temperature difference between cells and is a fundamental parameter for temperature correction. The open-circuit voltage (OCV) of a battery changes with temperature, and typically, the entropy thermal coefficient (dU / dT) reflects this relationship. The entropy thermal coefficient represents the slope of the battery voltage change with temperature and is an important parameter for temperature correction. Therefore, the entropy thermal coefficient (dU / dT) of each cell is obtained. For example, as... Figure 8 The curves showing the entropy-thermal coefficient variation of the battery under different SOCs are shown.

[0100] Finally, the difference in average temperature between each individual cell and the reference cell, ΔTi, is used to correct the differences in the charge-discharge curves (time-voltage) caused by temperature differences. The correction formula is as follows: U 修正 =U 原始 +dU / dT·△Ti.

[0101] By adjusting the voltage change curve based on temperature correction, the influence of temperature differences on voltage response is eliminated, making it closer to the behavior characteristics of the battery at standard temperatures.

[0102] Optionally, in the battery pack single-cell difference evaluation method provided in this application embodiment, the process of correcting the internal resistance of the first correction curve of each target single cell based on the incremental capacity curve of the reference single cell to obtain the second correction curve includes: obtaining the incremental capacity curve corresponding to each target single cell based on the first correction curve; determining a first voltage value based on the incremental capacity curve of the reference single cell, and determining a second voltage value corresponding to each target single cell based on the incremental capacity curve of each target single cell; and correcting the internal resistance of the first correction curve based on the difference between the first voltage value and the second voltage value to obtain the second correction curve.

[0103] In an optional embodiment, based on the first corrected curve obtained after temperature correction, the incremental capacity curve of each target single cell is obtained using incremental capacity analysis (ICA). The IC curve peaks reflect different stages in the battery's electrochemical reaction process, and the peak position on the IC curve shows a strong correlation with the battery voltage. It is effective for correcting SOC and internal resistance estimation. For cells connected in series, the current of each cell is the same; therefore, the different voltage shifts of the same IC curve peak from different cells can reflect the differences in internal resistance between the cells. For example, as... Figure 9 The diagram shows the dQ / dV curves (i.e., IC curves) of Cell-1, Cell-2, and Cell-3 after temperature correction.

[0104] Considering the differences in the SOC usage range of individual cells within the battery pack, some peaks of a single cell may not be very obvious. Therefore, this application selects the position of the highest main peak on the IC curve as the source of internal resistance difference information. Based on the voltage value corresponding to the main peak of the IC curve, the internal resistance difference reflected by each cell within the pack can be obtained. For example, by analyzing the incremental capacity curve of a reference cell, selecting the voltage value corresponding to the main peak of the IC curve for each cell, and calculating the voltage difference between each cell and the reference cell, the voltage offset ΔUi of each cell's curve relative to the reference cell's curve can be obtained. Subtracting this offset ΔUi from each cell's curve completes the internal resistance correction. The specific calculation formula is as follows:

[0105] Unew = Uold — (Up_curve_i — Up_curve_0)

[0106] Where Upnew and Uold are the selected cell voltages before and after correction, Up_curve_0 is the voltage value corresponding to the main peak of the IC curve of the reference cell, and Up_curve_i is the voltage value corresponding to the main peak of the IC curve of the other cells.

[0107] In an optional embodiment, a comparison diagram of the internal resistance correction values ​​of Cell-1, Cell-2, and Cell-3 obtained after the internal resistance (DCR) correction process of this application embodiment with the measured values ​​is shown below. Figure 10 As shown, from Figure 10 It can be seen that the corrected internal resistance value (i.e., the correction result) is basically consistent with the true internal resistance value (i.e., the experimental test). A schematic diagram illustrating the difference between the corrected internal resistance values ​​(i.e., the correction results) of Cell-2 and Cell-3 and the corrected internal resistance values ​​of the Cell-1 baseline group, and the difference between the true internal resistance values ​​(i.e., the experimental test) of Cell-2 and Cell-3 and the true internal resistance value of Cell-1, is shown below. Figure 11 As shown, it can be seen that the difference between the corrected internal resistance values ​​is basically consistent with the difference between the true internal resistance values.

[0108] Through the internal resistance correction process, the embodiments of this application can effectively eliminate the performance differences of individual cells in the battery pack caused by differences in internal resistance, and provide a more standardized voltage change curve for subsequent capacity correction and other evaluation processes.

[0109] Optionally, in the battery pack single cell difference evaluation method provided in the embodiments of this application, the second correction curve of each target single cell is modified to obtain the second voltage change curve by capacity correction, which includes: obtaining the open circuit voltage and state of charge relationship curve corresponding to each target single cell; and modifying the second correction curve of each target single cell according to the open circuit voltage and state of charge relationship curve to obtain the second voltage change curve.

[0110] In an optional embodiment, if the initial SOC of some cells is too low, resulting in the loss of voltage curve data at the end of charging, or if the initial SOC of some cells is too high, resulting in the loss of voltage curve data at the end of discharging, or if there is a problem with the loss of voltage curve data at the end of charging and discharging, the SOC-dynamic voltage table can be consulted, and the lost voltage curve data can be supplemented by time conversion. That is, the open circuit voltage-state of charge relationship curve (open circuit voltage-state of charge (OCV-SOC) curve) corresponding to each target cell can be obtained. The OCV-SOC curve records the open circuit voltage (OCV) value of the battery at different states of charge (SOC). Based on the open circuit voltage-state of charge relationship curve, the second correction curve of each target cell is adjusted for capacity to obtain the second voltage change curve.

[0111] Based on the data completion and capacity correction method of the OCV-SOC curve, the embodiments of this application can effectively address the problem of data loss caused by different SOC starting points during battery charging and discharging.

[0112] Optionally, in the battery pack single cell difference evaluation method provided in the embodiments of this application, the second correction curve of each target single cell is modified to obtain the second voltage change curve by performing capacity correction: obtaining the incremental capacity curve corresponding to each target single cell based on the first correction curve; and modifying the second correction curve to obtain the second voltage change curve based on the battery capacity value corresponding to the peak value in the incremental capacity curve corresponding to each target single cell.

[0113] In an optional embodiment, the first correction curve of each target cell after temperature and internal resistance correction is converted into an ICA curve (Incremental Capacity Analysis Curve). The ICA curve is a curve plotted as the relationship between the rate of voltage change and capacity during the charging and discharging process of the battery. It can reflect the details of the internal electrochemical reaction of the battery, especially the performance differences of the battery under different aging conditions.

[0114] Then, the peak value is identified in the ICA curve, and the corresponding battery capacity value is determined. This capacity value reflects the state of charge (SOC) at the location of the peak, which is an important characteristic point during battery charging and discharging. For example, as... Figure 12 As shown, the capacity increment curve (orange part) and the voltage change curve (blue part) are displayed. Figure 12 The vertical line in the diagram represents the peak value in the ICA curve, and the corresponding battery capacity value is determined based on this peak. Based on the battery capacity value corresponding to the peak value in the ICA curve, the second correction curve (i.e., the curve corrected for temperature and internal resistance) is truncated to the same capacity range to eliminate the impact of differences in the SOC starting point. For example, [the following is a possible interpretation, but the context is unclear]. Figure 12 The values ​​to the left of the vertical line are discarded, thus obtaining the second voltage change curve.

[0115] By adjusting the length of the curves, the voltage change curves of all individual cells are aligned within the same battery capacity range, achieving capacity standardization. This eliminates evaluation errors caused by capacity differences and provides a more accurate data foundation for subsequent battery pack performance evaluation and health management.

[0116] In an alternative embodiment, the following can be employed: Figure 13 The schematic diagram illustrates the evaluation of individual battery cell differences. It collects charge and discharge data of the lithium battery pack from continuous discharge from 100% SOC to 0% SOC or from 0% SOC to 100% SOC. Based on the charge and discharge data, it extracts the time-voltage curves of all cells, locates the cell that first reaches the charge / discharge cutoff voltage, selects this cell as the benchmark cell, and extracts the temperature of this cell during the charge / discharge process. To eliminate the influence of outliers, it performs smoothing filtering on the collected voltage and temperature data. Then, it calculates the average temperature of each battery cell and performs temperature correction based on the difference between the average temperature of the cell and the benchmark cell.

[0117] Calculate the reference cell IC curve, and use the charge-discharge curve corrected by temperature in the previous step to calculate the IC curves of the remaining cells. Select the voltage value corresponding to the main peak of the IC curve of each cell, and calculate the voltage difference between each cell and the reference cell. Then, the voltage offset ΔUi of each cell's battery curve relative to the reference cell curve can be obtained. Subtracting this offset ΔUi from each cell's battery curve completes the internal resistance correction.

[0118] The main sources of SOC discrepancies are: some cells have a low initial SOC during charging, leading to the loss of voltage curve data at the end of charging; others have a high initial SOC during discharging, resulting in the loss of voltage curve data at the end of discharging; and still others may have lost voltage curve data at the end of charging and discharging. In these three cases, the lost voltage curve data can generally be recovered by consulting the SOC-dynamic voltage table and calculating the time. This method is simple, reliable, and highly accurate. In addition, the main peak parameter of the IC curve can also be used to correct the SOC. The specific correction method is as follows: find the charging capacity value corresponding to the same capacity increment peak for each cell, extract all voltage data with a charging capacity greater than this value, and truncate the data to the shortest length to reconstruct the matrix. At this point, the initial SOC of each cell can be considered aligned.

[0119] Based on the battery pack's charging / discharging data, the charging and discharging processes of each individual cell within the pack are treated as independent processes. Each cell independently changes its charging and discharging current, effectively scaling the original charging and discharging curve proportionally over time. To quantify the difference or similarity between the two curves, the similarity between the scaled cell time-voltage curve and the reference cell time-voltage curve needs to be evaluated. The overlap between the reference cell time-voltage curve and the selected cell time-voltage curve is evaluated for similarity. A reasonable similarity threshold is set, and the current magnitude is gradually changed for iterative calculations until the similarity between the selected cell curve and the reference cell curve is greater than or equal to the set threshold. The iteration process ends at this point, recording the current and the time of the overlap. For capacity difference calculation, the difference between the iterative current Ii and the initial current Iinital is integrated over time t to obtain the capacity difference between the selected cell and the reference cell.

[0120] By calculating the average temperature difference between each individual cell and a reference cell, and performing voltage compensation based on the entropy-thermal coefficient, it is ensured that the charge-discharge curves of all individual cells reflect performance under the same temperature conditions. This eliminates the impact of temperature fluctuations on battery performance evaluation, even in complex operating environments, enabling consistent data acquisition and analysis. The voltage offset ΔUi between each cell and the reference cell is calculated using the voltage value at the main peak of the ICA curve, thus correcting memory differences. By extracting and reconstructing a data matrix aligned with the SOC range, it is ensured that the charge-discharge curves of all individual cells are compared within the same SOC range. Even if the initial SOC of some individual cells is at a non-standard position, SOC differences can be effectively eliminated through data completion and reconstruction, laying a solid foundation for subsequent capacity difference identification. The charge-discharge curves of individual cells are scaled proportionally along the time axis and compared with the reference cell curve. This process, through iterative calculation and threshold setting, accurately identifies and quantifies the capacity differences between individual cells, providing crucial data for battery pack balancing strategy formulation, fault warning, and lifespan prediction.

[0121] The battery pack individual cell difference evaluation method provided in this application embodiment obtains the operating data of the target battery pack, wherein the operating data is the charging data or discharging data of each individual cell in the target battery pack; based on the operating data, a reference individual cell is determined from multiple individual cells in the target battery pack; based on the voltage change curve of the reference individual cell, the difference between individual cells in the target battery pack is evaluated to obtain the target evaluation result. This solves the technical problem in related technologies where the accuracy of difference evaluation is relatively low when evaluating the difference between individual cells by measuring the terminal voltage or open circuit voltage of each individual cell in the lithium battery pack under static conditions.

[0122] In this approach, operational data of the target battery pack during charging and discharging is collected. Based on this data, a single cell is selected as a benchmark cell. Direct comparison with the benchmark cell accurately identifies differences in other cells, avoiding the uncertainties caused by voltage self-discharge differences between cells in static evaluation. Using the voltage variation curve of the benchmark cell, the performance of each cell in the target battery pack is evaluated to obtain the target evaluation result. Through the collection and analysis of dynamic data, and comparison with the benchmark cell, the consistency and trends of battery performance under actual operating conditions can be better reflected. This allows for a comprehensive assessment of the health status and differences of individual cells, achieving the technical effect of improving the accuracy of difference assessment.

[0123] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0124] Example 2

[0125] This application also provides a device for evaluating the differences between individual cells in a battery pack. It should be noted that this device can be used to execute the method for evaluating the differences between individual cells in a battery pack provided in this application. The following describes the device for evaluating the differences between individual cells in a battery pack provided in this application.

[0126] According to embodiments of this application, a device for evaluating the differences between individual cells in a battery pack, used for implementing the above-described method for evaluating the differences between individual cells in a battery pack, is also provided, such as... Figure 14 As shown, the device includes: a first acquisition unit 1401, a determination unit 1402, and a first evaluation unit 1403.

[0127] The first acquisition unit 1401 is used to acquire the operating data of the target battery pack, wherein the operating data is the charging data or discharging data of each individual cell in the target battery pack.

[0128] The determining unit 1402 is used to determine a reference cell from multiple individual cells in the target battery pack based on the operating data.

[0129] The first evaluation unit 1403 is used to evaluate the differences between individual cells in the target battery pack based on the voltage change curve of the reference individual cell, and obtain the target evaluation result.

[0130] The battery pack single-cell difference evaluation device provided in this application embodiment acquires the operating data of the target battery pack through the first acquisition unit 1401, wherein the operating data is the charging data or discharging data of each single cell in the target battery pack; the determination unit 1402 determines the reference single cell from multiple single cells in the target battery pack based on the operating data; the first evaluation unit 1403 evaluates the differences of the single cells in the target battery pack based on the voltage change curve of the reference single cell, and obtains the target evaluation result. This solves the technical problem in related technologies that the accuracy of difference evaluation is relatively low when evaluating the differences of single cells by measuring the terminal voltage or open circuit voltage of each single cell in the lithium battery pack in a static state.

[0131] In this approach, operational data of the target battery pack during charging and discharging is collected. Based on this data, a single cell is selected as a benchmark cell. Direct comparison with the benchmark cell accurately identifies differences in other cells, avoiding the uncertainties caused by voltage self-discharge differences between cells in static evaluation. Using the voltage variation curve of the benchmark cell, the performance of each cell in the target battery pack is evaluated to obtain the target evaluation result. Through the collection and analysis of dynamic data, and comparison with the benchmark cell, the consistency and trends of battery performance under actual operating conditions can be better reflected. This allows for a comprehensive assessment of the health status and differences of individual cells, achieving the technical effect of improving the accuracy of difference assessment.

[0132] Optionally, in the battery pack single cell difference evaluation device provided in the embodiments of this application, the determining unit includes: a first acquisition subunit, used to acquire the voltage change curve of each single cell from the operating data; a first determining subunit, used to determine the time information of each single cell reaching the cutoff voltage based on the voltage change curve; and a second determining subunit, used to determine the reference single cell from multiple single cells based on the time information.

[0133] Optionally, in the battery pack single-cell difference evaluation device provided in this application embodiment, the first evaluation unit includes: a first evaluation subunit, used to evaluate the capacity difference of the single cells of the target battery pack based on the voltage change curve of the reference single cell, and obtain a capacity difference evaluation result; a second evaluation subunit, used to evaluate the health status difference of the single cells of the target battery pack based on the capacity difference evaluation result, and obtain a health status difference evaluation result; and a third determination subunit, used to obtain a target evaluation result based on the capacity difference evaluation result and the health status difference evaluation result.

[0134] Optionally, in the battery pack single-cell difference evaluation device provided in this application embodiment, the first evaluation unit includes: a second acquisition subunit, used to acquire a first voltage change curve of a reference single cell under a first current value and acquire a second voltage change curve of each target single cell under a first current value, wherein the target single cell is a single cell in the target battery pack other than the reference single cell; a judgment subunit, used to judge whether the similarity between the first voltage change curve and the second voltage change curve is greater than or equal to a preset threshold; and an evaluation subunit, used to evaluate the differences of the single cells in the target battery pack based on the first voltage change curve and the second voltage change curve if the similarity is greater than or equal to the preset threshold, and obtain a target evaluation result.

[0135] Optionally, in the battery pack single-cell difference evaluation device provided in this application embodiment, the second acquisition subunit includes: a first correction module, used to perform temperature correction on the first initial voltage change curve of each target single cell under the first current value based on the temperature data of the reference single cell, to obtain a first correction curve; a second correction module, used to perform internal resistance correction on the first correction curve of each target single cell based on the incremental capacity curve of the reference single cell, to obtain a second correction curve; and a third correction module, used to perform capacity correction on the second correction curve of each target single cell, to obtain a second voltage change curve.

[0136] Optionally, in the battery pack single-cell difference evaluation device provided in this application embodiment, the first correction module includes: a first acquisition submodule, used to acquire a first average temperature value of a reference single cell and a second average temperature value of each target single cell based on operating data; a calculation submodule, used to calculate the difference between the first average temperature value and the second average temperature value to obtain a target difference; and a first correction submodule, used to perform temperature correction on the first initial voltage change curve based on the target difference and the entropy thermal coefficient of the target battery pack to obtain a first correction curve.

[0137] Optionally, in the battery pack single-cell difference evaluation device provided in this application embodiment, the second correction module includes: a first processing submodule, used to obtain the incremental capacity curve corresponding to each target single cell based on the first correction curve; a determination submodule, used to determine a first voltage value based on the incremental capacity curve of the reference single cell, and determine a second voltage value corresponding to each target single cell based on the incremental capacity curve corresponding to each target single cell; and a second correction submodule, used to perform internal resistance correction on the first correction curve based on the difference between the first voltage value and the second voltage value to obtain the second correction curve.

[0138] Optionally, in the battery pack single cell difference evaluation device provided in the embodiments of this application, the third correction module includes: a second acquisition submodule, used to acquire the open circuit voltage and state of charge relationship curve corresponding to each target single cell; and a third correction submodule, used to perform capacity correction on the second correction curve of each target single cell based on the open circuit voltage and state of charge relationship curve to obtain a second voltage change curve.

[0139] Optionally, in the battery pack single cell difference evaluation device provided in the embodiments of this application, the third correction module includes: a second processing submodule, used to obtain the incremental capacity curve corresponding to each target single cell based on the first correction curve; and a fourth correction submodule, used to perform capacity correction on the second correction curve based on the battery capacity value corresponding to the peak value in the incremental capacity curve corresponding to each target single cell, to obtain a second voltage change curve.

[0140] Optionally, in the battery pack single-cell difference evaluation device provided in this application embodiment, the device further includes: an execution unit, configured to, after determining whether the similarity between the first voltage change curve and the second voltage change curve is greater than or equal to a preset threshold, if the similarity is less than the preset threshold, repeatedly execute the steps of obtaining the third voltage change curve of the reference single cell under the second current value and obtaining the fourth voltage change curve of each target single cell under the second current value, until the similarity between the current voltage change curve of the reference single cell and the current voltage change curve of the target single cell is greater than or equal to the preset threshold; and a second evaluation unit, configured to evaluate the differences between the single cells of the target battery pack based on the current voltage change curve of the reference single cell and the current voltage change curve of the target single cell, and obtain the target evaluation result.

[0141] Optionally, in the battery pack single cell difference evaluation device provided in the embodiments of this application, the device further includes: a second acquisition unit for acquiring a current adjustment range; and an adjustment unit for adjusting a first current value according to the current adjustment range to obtain a second current value.

[0142] It should be noted that the first acquisition unit 1401, the determination unit 1402, and the first evaluation unit 1403 mentioned above correspond to steps S201 to S203 in Embodiment 1. The three units and the corresponding steps implement the same instances and application scenarios, but are not limited to the content disclosed in Embodiment 1. It should be noted that the above modules or units can be hardware or software components stored in memory (e.g., memory 104) and processed by one or more processors (e.g., processors 102a, 102b, ..., 102n). The above units can also be part of a device and run in the computer terminal 10 provided in Embodiment 1.

[0143] Example 3

[0144] Embodiments of this application may provide an electronic device. Figure 15 This is a structural block diagram of an electronic device according to an embodiment of this application. Figure 15 As shown, the electronic device may include: one or more ( Figure 15 (Only one is shown) Processor 1502, memory 1504, memory controller, and peripheral interface, wherein the peripheral interface is connected to the radio frequency module, audio module and display.

[0145] The memory can be used to store software programs and modules, such as the program instructions / modules corresponding to the methods and apparatus in the embodiments of this application. The processor executes various functional applications and data processing by running the software programs and modules stored in the memory, thereby implementing the above-described methods. The memory may include high-speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory may further include memory remotely located relative to the processor, and these remote memories can be connected to the terminal via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0146] The processor can access information and applications stored in the memory via a transmission device to perform the following steps: acquiring the operating data of the target battery pack, wherein the operating data is the charging or discharging data of each individual cell in the target battery pack; determining a reference cell from multiple individual cells in the target battery pack based on the operating data; evaluating the differences between individual cells in the target battery pack based on the voltage change curve of the reference cell, and obtaining the target evaluation result.

[0147] The processor can access information and applications stored in the memory via a transmission device to perform the following steps: determining a reference cell from multiple individual cells in the target battery pack based on operating data, including: obtaining the voltage change curve of each individual cell from the operating data; determining the time information of each individual cell reaching the cutoff voltage based on the voltage change curve; and determining the reference cell from multiple individual cells based on the time information.

[0148] The processor can access information and applications stored in the memory via a transmission device to execute the following steps: Based on the voltage variation curve of a reference cell, evaluate the differences between individual cells in the target battery pack to obtain the target evaluation result, including: evaluating the capacity differences between individual cells in the target battery pack based on the voltage variation curve of the reference cell, obtaining a capacity difference evaluation result; evaluating the health status differences between individual cells in the target battery pack based on the capacity difference evaluation result, obtaining a health status difference evaluation result; and obtaining the target evaluation result based on the capacity difference evaluation result and the health status difference evaluation result.

[0149] The processor can access information and applications stored in the memory via a transmission device to perform the following steps: Based on the voltage change curve of a reference cell, evaluate the differences between individual cells in the target battery pack to obtain the target evaluation result. This includes: acquiring the first voltage change curve of the reference cell at a first current value and acquiring the second voltage change curve of each target cell at a first current value, wherein the target cells are the individual cells in the target battery pack excluding the reference cell; determining whether the similarity between the first voltage change curve and the second voltage change curve is greater than or equal to a preset threshold; if the similarity is greater than or equal to the preset threshold, then evaluate the differences between the individual cells in the target battery pack based on the first voltage change curve and the second voltage change curve to obtain the target evaluation result.

[0150] The processor can access the information and application programs stored in the memory via the transmission device to perform the following steps: obtaining the second voltage change curve of each target cell at the first current value includes: performing temperature correction on the first initial voltage change curve of each target cell at the first current value based on the temperature data of the reference cell to obtain a first correction curve; performing internal resistance correction on the first correction curve of each target cell based on the incremental capacity curve of the reference cell to obtain a second correction curve; and performing capacity correction on the second correction curve of each target cell to obtain a second voltage change curve.

[0151] The processor can access the information and application program stored in the memory via the transmission device to execute the following steps: Correcting the temperature of the first initial voltage change curve of each target cell at a first current value based on the temperature data of the reference cell to obtain a first corrected curve includes: obtaining the first average temperature value of the reference cell and the second average temperature value of each target cell based on the operating data; calculating the difference between the first average temperature value and the second average temperature value to obtain a target difference; and correcting the temperature of the first initial voltage change curve based on the target difference and the entropy-thermal coefficient of the target battery pack to obtain the first corrected curve.

[0152] The processor can access information and applications stored in the memory via a transmission device to execute the following steps: Correcting the internal resistance of a first correction curve for each target cell based on the incremental capacity curve of a reference cell to obtain a second correction curve includes: obtaining the incremental capacity curve corresponding to each target cell based on the first correction curve; determining a first voltage value based on the incremental capacity curve of the reference cell, and determining a second voltage value corresponding to each target cell based on the incremental capacity curve of each target cell; correcting the internal resistance of the first correction curve based on the difference between the first and second voltage values ​​to obtain the second correction curve.

[0153] The processor can call the information and application stored in the memory through the transmission device to perform the following steps: perform capacity correction on the second correction curve of each target cell to obtain the second voltage change curve, including: obtaining the open circuit voltage and state of charge relationship curve corresponding to each target cell; and perform capacity correction on the second correction curve of each target cell based on the open circuit voltage and state of charge relationship curve to obtain the second voltage change curve.

[0154] The processor can call the information and application stored in the memory through the transmission device to perform the following steps: perform capacity correction on the second correction curve of each target single cell to obtain the second voltage change curve, including: obtaining the incremental capacity curve corresponding to each target single cell based on the first correction curve; and performing capacity correction on the second correction curve based on the battery capacity value corresponding to the peak value in the incremental capacity curve corresponding to each target single cell to obtain the second voltage change curve.

[0155] The processor can call the information and application stored in the memory through the transmission device to perform the following steps: After determining whether the similarity between the first voltage change curve and the second voltage change curve is greater than or equal to a preset threshold, the method further includes: if the similarity is less than the preset threshold, repeating the steps of obtaining the third voltage change curve of the reference cell at the second current value and obtaining the fourth voltage change curve of each target cell at the second current value until the similarity between the current voltage change curve of the reference cell and the current voltage change curve of the target cell is greater than or equal to the preset threshold; evaluating the differences between the individual cells of the target battery pack based on the current voltage change curve of the reference cell and the current voltage change curve of the target cell to obtain the target evaluation result.

[0156] The processor can access information and applications stored in the memory via a transmission device to perform the following steps: obtain the current adjustment range; adjust the first current value according to the current adjustment range to obtain the second current value.

[0157] Those skilled in the art will understand that Figure 6 The structure shown is for illustrative purposes only. Electronic devices can also be smartphones, tablets, handheld computers, mobile internet devices (MIDs), PADs, and other terminal devices. Figure 6 This does not limit the structure of the aforementioned electronic device. For example, electronic devices may also include components that are more... Figure 6 The more or fewer components shown (such as network interfaces, display devices, etc.), or having the same Figure 6 The different configurations shown.

[0158] Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be implemented by a program instructing the hardware related to the terminal device. The program can be stored in a computer-readable storage medium, which may include: flash drive, read-only memory (ROM), random access memory (RAM), disk or optical disk, etc.

[0159] Example 4

[0160] Embodiments of this application also provide a computer-readable storage medium. Optionally, in this embodiment, the storage medium can be used to store the program code executed by the single-cell difference evaluation method for the battery pack provided in Embodiment 1.

[0161] Optionally, in this embodiment, the storage medium may be located in any computer terminal in a group of computer terminals in a computer network, or in any mobile terminal in a group of mobile terminals.

[0162] This application also provides a computer program product, which, when executed on a data processing device, is suitable for performing the steps of a method for evaluating the differences between individual cells in a battery pack.

[0163] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0164] In the above embodiments of this application, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0165] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0166] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0167] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0168] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it 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 includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, read-only memory (ROM), random access memory (RAM), portable hard drive, magnetic disk, or optical disk.

[0169] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A method for evaluating the differences between individual cells in a battery pack, characterized in that, include: Obtain the operating data of the target battery pack, wherein the operating data is the charging data or discharging data of each individual cell in the target battery pack; Based on the operational data, a reference cell is determined from among the multiple individual cells in the target battery pack; Based on the voltage variation curve of the reference single cell, the differences between the single cells of the target battery pack are evaluated to obtain the target evaluation result.

2. The method according to claim 1, characterized in that, The step of determining a reference cell from multiple individual cells in the target battery pack based on the operational data includes: The voltage change curve of each individual battery cell is obtained from the operational data; Based on the voltage change curve, determine the time information for each individual cell to reach the cutoff voltage; Based on the time information, the reference cell is determined from the plurality of individual cells.

3. The method according to claim 1, characterized in that, The evaluation of the differences between individual cells in the target battery pack based on the voltage variation curve of the reference cell yields the following target evaluation results: Based on the voltage change curve of the reference single cell, the capacity difference of the single cells in the target battery pack is evaluated to obtain the capacity difference evaluation result; Based on the capacity difference assessment results, the health status differences of the individual cells in the target battery pack are assessed to obtain the health status difference assessment results; The target assessment result is obtained based on the capacity difference assessment result and the health status difference assessment result.

4. The method according to claim 1, characterized in that, The evaluation of the differences between individual cells in the target battery pack based on the voltage variation curve of the reference cell yields the following target evaluation results: Obtain the first voltage change curve of the reference single cell under the first current value and obtain the second voltage change curve of each target single cell under the first current value, wherein the target single cell is a single cell in the target battery pack other than the reference single cell; Determine whether the similarity between the first voltage change curve and the second voltage change curve is greater than or equal to a preset threshold; If the similarity is greater than or equal to the preset threshold, the differences between the individual cells of the target battery pack are evaluated based on the first voltage change curve and the second voltage change curve to obtain the target evaluation result.

5. The method according to claim 4, characterized in that, The step of obtaining the second voltage change curve of each target single cell at the first current value includes: Based on the temperature data of the reference single cell, the first initial voltage change curve of each target single cell at the first current value is corrected by temperature to obtain the first correction curve; Based on the incremental capacity curve of the reference single cell, the internal resistance of the first correction curve of each target single cell is corrected to obtain the second correction curve; The second correction curve for each target single cell is modified for capacity to obtain the second voltage change curve.

6. The method according to claim 5, characterized in that, The step of performing temperature correction on the first initial voltage change curve of each target cell at the first current value based on the temperature data of the reference cell to obtain the first correction curve includes: Based on the operating data, the first average temperature value of the reference single cell and the second average temperature value of each target single cell are obtained; The difference between the first average temperature value and the second average temperature value is calculated to obtain the target difference value; The first initial voltage change curve is corrected for temperature based on the target difference and the entropy thermal coefficient of the target battery pack to obtain the first corrected curve.

7. The method according to claim 5, characterized in that, The process of correcting the internal resistance of the first correction curve for each target cell based on the incremental capacity curve of the reference cell to obtain the second correction curve includes: Based on the first correction curve, the incremental capacity curve corresponding to each target single cell is obtained; Based on the incremental capacity curve of the reference single cell, a first voltage value is determined, and based on the incremental capacity curve of each target single cell, a second voltage value corresponding to each target single cell is determined. The first correction curve is corrected for internal resistance based on the difference between the first voltage value and the second voltage value to obtain the second correction curve.

8. The method according to claim 5, characterized in that, The process of performing capacity correction on the second correction curve for each target single cell to obtain the second voltage change curve includes: Obtain the open-circuit voltage versus state of charge curve for each target cell. Based on the open-circuit voltage and state of charge relationship curve, the capacity of the second correction curve of each target single cell is corrected to obtain the second voltage change curve.

9. The method according to claim 5, characterized in that, The second correction curve for each target single cell is modified for capacity, resulting in the second voltage change curve, which includes: Based on the first correction curve, the incremental capacity curve corresponding to each target single cell is obtained; Based on the battery capacity value corresponding to the peak value in the incremental capacity curve for each target single cell, the second correction curve is corrected for capacity to obtain the second voltage change curve.

10. The method according to claim 4, characterized in that, After determining whether the similarity between the first voltage change curve and the second voltage change curve is greater than or equal to a preset threshold, the method further includes: If the similarity is less than the preset threshold, the steps of obtaining the third voltage change curve of the reference cell at the second current value and obtaining the fourth voltage change curve of each target cell at the second current value are repeated until the similarity between the current voltage change curve of the reference cell and the current voltage change curve of the target cell is greater than or equal to the preset threshold. The differences between the individual cells of the target battery pack are evaluated based on the current voltage change curve of the reference cell and the current voltage change curve of the target cell, and the target evaluation result is obtained.

11. The method according to claim 10, characterized in that, The method further includes: Obtain the current adjustment range; Based on the current adjustment range, the first current value is adjusted to obtain the second current value.

12. A device for evaluating the differences between individual cells in a battery pack, characterized in that, include: The first acquisition unit is used to acquire the operating data of the target battery pack, wherein the operating data is the charging data or discharging data of each individual cell in the target battery pack; The determining unit is configured to determine a reference single cell from multiple single cells in the target battery pack based on the operating data. The first evaluation unit is used to evaluate the differences between individual cells in the target battery pack based on the voltage change curve of the reference individual cell, and obtain the target evaluation result.

13. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored executable program, wherein, when the executable program is executed, it controls the device on which the computer-readable storage medium is located to perform the single-cell difference evaluation method for the battery pack according to any one of claims 1 to 11.

14. An electronic device, characterized in that, include: Memory, which stores executable programs; A processor for running the program, wherein the program, when running, executes the method for evaluating the individual cell differences of a battery pack according to any one of claims 1 to 11.

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