CN-122017648-A - Single battery difference evaluation method and device of battery pack

CN122017648ACN 122017648 ACN122017648 ACN 122017648ACN-122017648-A

Abstract

The application discloses a single battery difference evaluation method and device of a battery pack, and relates to the technical field of batteries, wherein the method comprises the steps of obtaining operation data of a target battery pack, wherein the operation data are charging data or discharging data of each single battery in the target battery pack; 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. According to the application, the problem of 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 static state in the related art is solved.

Inventors

LI SHENGDE
WANG ZUN
LIU YONG
SUN SHIQIANG

Assignees

兰钧新能源科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260211

Claims (14)

1. A method for evaluating a difference between unit cells of a battery pack, comprising: Acquiring operation data of a target battery pack, wherein the operation data are 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.
2. The method of claim 1, wherein determining a reference cell from a plurality of cells in the target battery pack based on the operational data comprises: acquiring a voltage change curve of each single battery from the operation data; Determining time information of each single battery reaching the cut-off voltage according to the voltage change curve; and determining the reference single battery from the plurality of single batteries according to the time information.
3. The method of claim 1, wherein evaluating the difference between the cells of the target battery pack according to the voltage change curve of the reference cell, to obtain a target evaluation result comprises: According to the voltage change curve of the reference single battery, evaluating the capacity difference of the single battery of the target battery pack to obtain a capacity difference evaluation result; Evaluating the difference of the health states of the single batteries of the target battery pack according to the capacity difference evaluation result to obtain a health state difference evaluation result; and obtaining the target evaluation result according to the capacity difference evaluation result and the health state difference evaluation result.
4. The method of claim 1, wherein evaluating the difference between the cells of the target battery pack according to the voltage change curve of the reference cell, to obtain a target evaluation result comprises: Acquiring a first voltage change curve of the reference single battery under a first current value and acquiring a second voltage change curve of each target single battery under the first current value, wherein the target single battery is a single battery except the reference single battery in the target battery pack; judging whether the similarity of the first voltage change curve and the second voltage change curve is larger than or equal to a preset threshold value; And if the similarity is greater than or equal to the preset threshold, evaluating the difference of the single batteries of the target battery pack according to the first voltage change curve and the second voltage change curve to obtain the target evaluation result.
5. The method of claim 4, wherein the obtaining a second voltage profile for each target cell at the first current value comprises: Temperature correction is carried out on a first initial voltage change curve of each target single battery under the first current value according to the temperature data of the reference single battery, so that a first correction curve is obtained; performing internal resistance correction on the first correction curve of each target single battery according to the increment capacity curve of the reference single battery to obtain a second correction curve; And carrying out capacity correction on the second correction curve of each target single battery to obtain the second voltage change curve.
6. The method of claim 5, wherein the performing temperature correction on the first initial voltage change curve of each target cell at the first current value according to the temperature data of the reference cell, to obtain a first correction curve comprises: Acquiring a first average temperature value of the reference single battery and a second average temperature value of each target single battery according to the operation data; calculating the difference value of the first average temperature value and the second average temperature value to obtain a target difference value; And carrying out temperature correction on the first initial voltage change curve according to the target difference value and the entropy heat coefficient of the target battery pack to obtain the first correction curve.
7. The method of claim 5, wherein performing the internal resistance correction on the first correction curve of each target cell according to the incremental capacity curve of the reference cell to obtain the second correction curve comprises: obtaining an incremental capacity curve corresponding to each target single battery according to the first correction curve; Determining a first voltage value according to the increment capacity curve of the reference single battery, and determining a second voltage value corresponding to each target single battery according to the increment capacity curve corresponding to each target single battery; And performing internal resistance correction on the first correction curve according to the difference value between the first voltage value and the second voltage value to obtain the second correction curve.
8. The method of claim 5, wherein performing capacity correction on the second correction curve for each target cell to obtain the second voltage variation curve comprises: acquiring a relation curve of open circuit voltage and charge state corresponding to each target single battery; and carrying out capacity correction on the second correction curve of each target single battery according to the relation curve of the open-circuit voltage and the state of charge to obtain the second voltage change curve.
9. The method of claim 5, wherein performing capacity correction on a second correction curve for each target cell, the second voltage variation curve comprising: obtaining an incremental capacity curve corresponding to each target single battery according to the first correction curve; And carrying out capacity correction on the second correction curve according to the battery capacity value corresponding to the peak value in the increment capacity curve corresponding to each target single battery, so as to obtain the second voltage change curve.
10. The method of claim 4, wherein after said determining whether the similarity of the first voltage profile and the second voltage profile is greater than or equal to a preset threshold, the method further comprises: If the similarity is smaller than the preset threshold, repeating the steps of acquiring a third voltage change curve of the reference single battery under the second current value and acquiring a fourth voltage change curve of each target single battery under the second current value until the similarity of the current voltage change curve of the reference single battery and the current voltage change curve of the target single battery is larger than or equal to the preset threshold; and evaluating the difference of the single batteries of the target battery pack according to the current voltage change curve of the reference single battery and the current voltage change curve of the target single battery to obtain the target evaluation result.
11. The method according to claim 10, wherein the method further comprises: acquiring a current adjustment range; and adjusting the first current value according to the current adjustment range to obtain the second current value.
12. A single cell difference evaluation device of a battery pack, characterized by comprising: A first obtaining unit, configured to obtain operation data of a target battery pack, where the operation data is charging data or discharging data of each unit cell in the target battery pack; A determining unit configured to determine a reference cell from a plurality of cells in the target battery pack according to the operation data; and the first evaluation unit is used for 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.
13. A computer-readable storage medium, characterized in that the computer-readable storage medium includes a stored executable program, wherein the executable program, when run, controls a device in which the computer-readable storage medium is located to perform the cell difference evaluation method of the battery pack according to any one of claims 1 to 11.
14. An electronic device, comprising: A memory storing an executable program; A processor for executing the program, wherein the program executes the cell difference evaluation method of the battery pack according to any one of claims 1 to 11 when executed.

Description

Single battery difference evaluation method and device of battery pack Technical Field The application relates to the technical field of batteries, in particular to a single battery difference evaluation method and device of a battery pack. Background In the management and application fields of lithium ion batteries, ensuring the consistency of single batteries in the batteries is a key for improving the overall performance and safety. A method commonly adopted in the related art is to evaluate the difference between the cells by measuring the terminal voltage or open circuit voltage of each cell in a stationary state. However, such static evaluation methods have significant limitations, and only reflect the voltage difference at a specific time point, but neglect the actual performance of the battery in the dynamic charge and discharge process, resulting in a problem that the accuracy of the difference evaluation is relatively low. Aiming at the problem that in the related art, the difference of the single batteries is evaluated by measuring the terminal voltage or the open circuit voltage of each single battery in the lithium battery pack in a standing state, so that the accuracy of the difference evaluation is lower, no effective solution is proposed at present. Disclosure of Invention The application mainly aims to provide a single battery difference evaluation method and device of a battery pack, which are used for solving the problem that in the related art, the accuracy of difference evaluation is lower due to the fact that the single battery difference is evaluated by measuring the terminal voltage or the open-circuit voltage of each single battery in the lithium battery pack in a standing state. In order to achieve the above object, according to one aspect of the present application, there is provided a battery cell difference evaluation method of a battery pack. The method comprises the steps of obtaining operation data of a target battery pack, wherein the operation data are 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 differences of the single batteries of the target battery pack according to a voltage change curve of the reference single battery to obtain a target evaluation result. Further, determining the reference single battery from the plurality of single batteries in the target battery pack according to the operation data comprises the steps of obtaining a voltage change curve of each single battery from the operation data, determining time information of reaching an ending voltage of each single battery according to the voltage change curve, and determining the reference single battery from the plurality of single batteries according to the time information. Further, according to the voltage change curve of the reference single battery, the difference of the single batteries of the target battery pack is evaluated, and a target evaluation result is obtained, wherein the evaluation of the difference of the single batteries of the target battery pack according to the voltage change curve of the reference single battery is carried out to obtain a capacity difference evaluation result, the health state difference of the single batteries of the target battery pack is evaluated according to the capacity difference evaluation result to obtain a health state difference evaluation result, and the target evaluation result is obtained according to the capacity difference evaluation result and the health state difference evaluation result. Further, according to the voltage change curve of the reference single battery, the difference of the single batteries of the target battery pack is evaluated, and a target evaluation result is obtained, wherein the target evaluation result comprises the steps of obtaining a first voltage change curve of the reference single battery under a first current value and obtaining a second voltage change curve of each target single battery under the first current value, wherein the target single battery is the single battery except the reference single battery in the target battery pack, judging whether the similarity of the first voltage change curve and the second voltage change curve is larger than or equal to a preset threshold value, and if the similarity is larger than or equal to the preset threshold value, evaluating the difference of the single batteries of the target battery pack according to the first voltage change curve and the second voltage change curve, and obtaining the target evaluation result. Further, obtaining a second voltage change curve of each target single battery under the first current value comprises the steps of carrying out temperature correction on a first initial voltage change curve of each target single battery under the first current value accordin