CN-121978566-A - System and method for detecting soft short circuit in battery

Abstract

Systems and methods for detecting soft shorts in batteries are provided. A system, vehicle, and method for detecting soft shorts in a battery utilize one or both of a first algorithm and a second algorithm to measure impedance of the battery at N z frequency points and at one or more voltages (e.g., using electrochemical impedance spectroscopy), calculate one or more errors, determine a number of occurrences of one of the calculated errors being greater than a threshold error, and identify the battery as having a soft short if the number of occurrences is greater than a threshold.

Inventors

• I.Chang
• HASKARA IBRAHIM
• M.P. Buck
• W.G. Zanadley

Assignees

• 通用汽车环球科技运作有限责任公司

Dates

Publication Date

20260505

Application Date

20241227

Priority Date

20241030

Claims (10)

1. 1. A method for detecting a soft short in a battery, comprising: measuring the impedance of the battery at N z frequency points within the frequency range and at a selected voltage below a predetermined voltage level, thereby producing N z respective measured impedances each having a respective real component; Calculating a respective error for each of the N z measured impedances by comparing the respective real component of each measured impedance to a respective reference impedance representing a healthy battery, thereby producing N z respective calculated errors; Determining a number of occurrences of one of the N z calculated errors being greater than the threshold error, and If the number of occurrences is greater than the threshold, the battery is identified as having a soft short.
2. 2. The method of claim 1, wherein impedance measurements at N z frequency points are made using electrochemical impedance spectroscopy.
3. 3. The method of claim 1, wherein the frequency range is about 0.01 to 1Hz.
4. 4. The method of claim 1, wherein each reference impedance is: An average real impedance component acting as a proxy for healthy batteries, or Representing a respective member of the set of real impedance components of a healthy battery.
5. 5. The method of claim 4, wherein the average real impedance component is obtained from an average of respective real components of respective impedances from two or more other batteries configured for use with batteries measured at a selected voltage and within a frequency range.
6. 6. The method of claim 4, wherein each respective member of the set of real impedance components corresponds to a respective one of the N z frequency points.
7. 7. The method of claim 1, wherein each reference impedance is obtained from a look-up table.
8. 8. The method of claim 1, wherein each measured impedance has a respective imaginary component.
9. 9. The method of claim 1, wherein the predetermined voltage level is defined as a voltage level below which the real component of the measured impedance of the soft short cell differs significantly from the real component of the reference impedance of the healthy cell over the frequency range.
10. 10. The method of claim 1, wherein the battery is a lithium ion battery, and wherein the predetermined voltage level is approximately 3.5 volts.

Description

System and method for detecting soft short circuit in battery Technical Field The present disclosure relates to systems and methods for detecting soft shorts in a battery (e.g., a battery module or a battery cell or group of battery cells within a battery pack). Background In battery-powered devices, such as automobiles, prediction of battery health plays an important role in battery management. Electrochemical Impedance Spectroscopy (EIS) is a viable method of monitoring battery health. EIS can be used to stimulate the cell and measure voltage changes, which then allows impedance analysis. However, there is a lack of clarity regarding impedance data (e.g., effective frequency range, etc.) and subsequent processing required to detect battery health anomalies (e.g., soft shorts). Disclosure of Invention According to one embodiment, a method for detecting soft shorts in a battery includes (i) measuring impedance of the battery at N z frequency points within a frequency range and at a selected voltage below a predetermined voltage level, thereby producing N z respective measured impedances each having a respective real component, (ii) calculating a respective error for each of the N z measured impedances by comparing the respective real component of each measured impedance to a respective reference impedance representative of a healthy battery, thereby producing N z respective calculated errors, (iii) determining that one of the N z calculated errors is greater than a number of occurrences of a threshold error, and (iv) identifying the battery as having soft shorts if the number of occurrences is greater than a threshold. Impedance measurements at N z frequency points can be made using electrochemical impedance spectroscopy, and the frequency range can be about 0.01 to 1Hz. Each reference impedance may be (i) an average real impedance component that acts as a proxy for a healthy battery, or (ii) a respective member of a set of real impedance components that represent a healthy battery. The average real impedance component may be obtained from an average of respective real components from respective impedances of two or more other batteries configured for use with batteries measured at a selected voltage and within a frequency range. Each respective member of the set of real impedance components may correspond to a respective one of the N z frequency points. Each reference impedance may be obtained from a look-up table and each measured impedance may have a corresponding imaginary component. The predetermined voltage level may be defined as a voltage level below which the real component of the measured impedance of the soft short cell differs significantly from the real component of the reference impedance of the healthy cell in the frequency range. The impedance of the battery may be measured at approximately the same temperature at N z frequency points. The battery may be a lithium ion battery, wherein the predetermined voltage level is approximately 3.5 volts. According to another embodiment, a method for detecting soft shorts in a battery includes (i) measuring the impedance of the battery at N z frequency points within a frequency range and at respective main and substitute voltages, each of the main and substitute voltages being above a predetermined voltage level, thereby producing N z pairs of respective measured main and substitute impedances, each of the main and substitute impedances having respective real components, (ii) calculating the respective measured impedance error for each of the N z pairs by comparing the respective real components of the respective measured main impedances with the respective real components of the respective measured substitute impedances, thereby producing respective measured impedance errors, (iii) calculating the respective reference impedance error for each of the N z pairs by comparing the respective real components of the respective main reference impedances corresponding to the main voltage with the respective real components of the respective substitute reference impedances, thereby producing N z respective reference impedance errors, (iv) calculating the respective error for each of the N z pairs by dividing the difference between the respective measured impedance error and the respective reference impedance error by the respective reference impedance error, thereby producing a maximum number of error, and (vi) determining that the error has occurred for the largest number of times of soft shorts of one of the largest errors (vi) occurs. In this embodiment, impedance measurements at N z frequency points may be made using electrochemical impedance spectroscopy, and the frequency range may be about 0.1 to 10Hz. At least one of the primary reference impedance and the alternate reference impedance may be (i) an average real impedance component that is a proxy for a healthy battery, or (ii) a respective member of a set of real impedance components that represent a he