Battery Pack State Detection Using Block Ratio Moving Averages
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for detecting the degraded state of a battery pack comprising series-connected parallel-cell blocks are inadequate due to variations in internal resistance values among cells, leading to inaccurate detection of degraded states.
Innovation Solution
A device and method that determine the state of a battery pack by calculating a parameter ratio of a parallel-cell block to an average value of multiple blocks, using a moving-average value to identify an index value that accurately reflects the block's state, and outputting warning or identification information when deviations occur.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the internal resistance value of a parallel-cell block is used to detect battery degradation, then the detection method is simple, but the detection accuracy deteriorates when cells have significantly different internal resistance values
Solution Approach 1:
The battery pack is divided into multiple parallel-cell blocks, and the detection is performed at the individual block level rather than treating the entire pack as a single unit. This segmentation allows identification of degraded cells within each block by comparing their specific internal resistance values against the block's average, enabling accurate detection even when cells have significantly different resistance values.
2Quantity of substance
If multiple parallel-cell blocks are connected in series to increase power storing capacity, then the battery capacity increases, but the complexity of accurately detecting the state of each block increases
Solution Approach 1:
Each parallel-cell block serves as its own reference by calculating its own average internal resistance value from its constituent cells. This self-service approach allows independent evaluation of each block's state without requiring external reference measurements, simplifying the detection system while maintaining accuracy across multiple series-connected blocks.
3Measurement precision
If the average internal resistance value of cells in a parallel-cell block is calculated, then the overall block resistance is obtained, but the degraded state of individual cells is masked
Solution Approach 1:
The detection method applies different evaluation criteria to different levels of the battery structure: the average internal resistance is used to characterize the overall block state, while individual cell internal resistance values are separately evaluated to identify degraded cells. This local quality approach preserves both the macroscopic block characteristics and microscopic cell-level degradation information simultaneously.
Data Source
AI summary
A parameter ratio that is a ratio of a parameter of a parallel-cell block to be determined to an average value of parameters of a plurality of parallel-cell blocks is calculated, a moving-average value of the parameter ratio is obtained, and a state of the parallel-cell block to be determined is determined based on an index value that is a difference between the parameter of the parallel-cell block to be determined and the moving-average value.