Battery Degradation Detection Using Multi-Rate Differential Capacity
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Solution Overview
Problem
Current methods for determining battery degradation information are inadequate, particularly when voltage changes are not clearly observed in capacity curves, and differential capacity analysis fails to adequately reflect hysteresis characteristics associated with battery degradation when using a single current rate for charge or discharge processes.
Innovation Solution
A battery management apparatus and method that acquires and analyzes four differential capacity curves by performing charge and discharge processes at least once using two different constant currents, detecting feature points and hysteresis values to determine battery degradation information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If differential capacity analysis is performed using a single current rate, then the analysis process is simple, but hysteresis characteristics associated with battery degradation are not sufficiently reflected
Solution Approach 1:
The patent applies parameter changes by performing differential capacity analysis at multiple current rates (first current rate and second current rate) rather than a single current rate. This changes the operational parameters of the analysis to capture hysteresis characteristics that are not visible at a single current rate, thereby improving degradation information accuracy while maintaining manageable process complexity through systematic multi-rate testing.
2Device complexity
If capacity curve is used for degradation determination, then the method is simple, but accurate degradation information cannot be obtained when voltage changes are not clearly observed
Solution Approach 1:
The patent transforms the analysis approach by changing from direct capacity curve analysis to differential capacity curve analysis. This parameter transformation (from dQ/dV to d²Q/dV²) enhances the visibility of voltage changes and degradation features that are not clearly observable in standard capacity curves, enabling accurate degradation determination even when voltage changes are subtle.
3Loss of time
If only one charge or discharge process is performed, then the testing process is simple, but hysteresis characteristics are not adequately captured
Solution Approach 1:
The patent applies segmentation by dividing the testing process into multiple distinct charge and discharge processes performed at different current rates. Instead of a single continuous test, the methodology segments the analysis into discrete charge-discharge cycles, each contributing specific hysteresis information that collectively provides comprehensive degradation characterization.
Data Source
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AI summary
Provided are a battery management apparatus, a battery management method and a battery pack. The battery management apparatus includes detects feature points of each of a first differential capacity curve acquired by charging the battery with a first constant current, a second differential capacity curve acquired by discharging the battery with the first constant current, a third differential capacity curve acquired by charging the battery with a second constant current and a fourth differential capacity curve acquired by discharging the battery with the second constant current, and determines degradation information of the battery based on voltage values of the feature points detected from each differential capacity curve.