Battery Pack Impedance Screening for Connection and Cell Consistency
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Solution Overview
Problem
Conventional methods for detecting the consistency of battery packs struggle to accurately identify inconsistencies within the battery pack, particularly due to unreliable electrical connections such as cold solder joints, which can be more significant than internal cell differences in affecting reliability.
Innovation Solution
A method and device utilizing an electrochemical workstation with auxiliary voltage measurements to detect AC impedance spectra of battery cells or modules, comparing ohmic and charge transfer impedances to determine consistency, allowing for rapid and non-destructive analysis of both cell and connection point consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional single-channel electrochemical workstation is used to detect battery pack consistency, then measurement precision of single cell is improved, but productivity and detection speed deteriorate due to sequential measurement requirement
Solution Approach 1:
The patent divides the battery pack into multiple detectable units (cells or modules) and uses multiple detection channels to measure them simultaneously. The electrochemical workstation is configured with multiple channels that can independently measure different cells in parallel, transforming a sequential single-channel process into a parallel multi-channel process, thereby improving detection speed while maintaining measurement precision.
Solution Approach 2:
The patent combines multiple detection channels into a single integrated measurement system. By merging the capabilities of multiple channels into one electrochemical workstation, the system achieves both high-speed parallel measurement and comprehensive analysis of battery pack consistency, resolving the contradiction between precision and productivity.
2Productivity
If multi-channel electrochemical workstation is used to measure multiple cells simultaneously, then productivity is improved, but ability to detect connection point issues deteriorates due to lack of localized impedance information
Solution Approach 1:
The patent applies segmentation by separating the impedance measurement into two distinct components: ohmic impedance (R0) representing connection point quality, and charge transfer impedance (Rct) representing cell performance. This segmentation allows the system to simultaneously evaluate both connection reliability and cell consistency using the same multi-channel measurement data, thereby maintaining high detection speed while improving connection point detection capability.
Solution Approach 2:
The patent focuses on local quality by specifically analyzing ohmic impedance as an indicator of connection point quality. By extracting and analyzing the R0 parameter from the impedance spectra, the system can identify local connection issues such as cold solder joints without compromising the overall productivity of the multi-channel measurement system.
3Device complexity
If traditional electrochemical workstation without auxiliary voltage measurements is used, then device complexity is reduced, but ability to simultaneously detect cell and connection consistency deteriorates
Solution Approach 1:
The patent makes the electrochemical workstation multi-functional by enabling it to perform both cell consistency detection and connection point detection using the same hardware platform. By utilizing auxiliary voltage measurements and analyzing impedance spectra parameters (R0 and Rct), the workstation achieves comprehensive detection capabilities without requiring separate specialized equipment, thus maintaining simplicity while improving detection precision.
Solution Approach 2:
The patent employs parameter changes by analyzing different parameters from the impedance spectra (specifically R0 and Rct values) to extract different types of information. By changing the analysis focus between these parameters, the system can detect both connection quality and cell consistency using the same measurement data, eliminating the need for additional complex hardware while improving detection precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables effective detection of abnormal connections and cell inconsistencies within battery packs, improving the reliability of electrical connections and extending the cycle life of battery packs by identifying and addressing cold solder joints without damaging the battery pack.
Implementation Method 1
simultaneously detecting AC impedance spectra of the plurality of cells or the plurality of parallel battery modules through the auxiliary voltage measurements on the basis that the electrochemical workstation applies AC signals with different frequencies and specific amplitudes to the battery pack
Implementation Method 2
comparing corresponding ohmic impedances and charge transfer impedances in the AC impedance spectra of the plurality of cells or the plurality of parallel battery modules to determine the consistency of the battery pack
Data Source
AI summary
The present disclosure provides a method and device for detecting the consistency of connection points of a battery pack. The battery pack includes a plurality of cells or a plurality of parallel battery modules, and the connection points are arranged among the plurality of cells or the plurality of parallel battery modules. The method is based on an electrochemical workstation with auxiliary voltage measurements, and includes the following steps: simultaneously detecting AC impedance spectra of the plurality of cells or the plurality of parallel battery modules through the auxiliary voltage measurements on the basis that the electrochemical workstation applies AC signals with different frequencies and specific amplitudes to the battery pack; and comparing corresponding ohmic impedances and charge transfer impedances in the AC impedance spectra of the plurality of cells or the plurality of parallel battery modules to determine the consistency of the battery pack.