Battery Impedance Diagnosis Using Selective Frequency Measurement
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Solution Overview
Problem
Existing battery diagnosis methods require measuring impedance at multiple SOC values across various frequencies, leading to increased data amounts and processing complexity, while still needing to accurately determine battery degradation states.
Innovation Solution
A method where the impedance of a battery is measured at a first frequency for multiple SOC values, determining a target SOC value based on a change ratio threshold, and then measuring the impedance at a second higher frequency only for the target SOC values, using these measurements to determine the battery's state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If impedance is measured at multiple SOC values across various frequencies, then measurement precision of battery state is improved, but quantity of data increases
Solution Approach 1:
The patent segments the frequency measurement process into two distinct stages: a first frequency measurement performed at multiple SOC values, and a second frequency measurement performed only at selected SOC values where the impedance change ratio exceeds a threshold. This segmentation reduces the total number of measurements while preserving critical diagnostic information for battery state determination.
Solution Approach 2:
The patent applies local quality by identifying specific SOC values where the impedance change ratio exceeds a predetermined threshold, and performing the second frequency measurement only at those localized points. This targeted approach focuses measurement resources on the most diagnostically valuable SOC regions rather than uniformly measuring all SOC values.
2Measurement precision
If impedance is measured at multiple SOC values across various frequencies, then measurement precision of battery state is improved, but device complexity increases
Solution Approach 1:
The patent segments the frequency measurement process into two distinct stages: a first frequency measurement performed at multiple SOC values, and a second frequency measurement performed only at selected SOC values where the impedance change ratio exceeds a threshold. This segmentation reduces the total number of measurements while preserving critical diagnostic information for battery state determination.
Solution Approach 2:
The patent applies local quality by identifying specific SOC values where the impedance change ratio exceeds a predetermined threshold, and performing the second frequency measurement only at those localized points. This targeted approach focuses measurement resources on the most diagnostically valuable SOC regions rather than uniformly measuring all SOC values.
Data Source
AI summary
In a diagnosis method of a battery of an embodiment, based on a measurement result of a first impedance of a battery at a first frequency, it is determined, for each of a plurality of SOC values, whether an absolute value of a change ratio of the first impedance to the SOC is not more than a reference value. In the diagnosis method, for a target SOC value whose absolute value of the change ratio is not more than the reference value in the plurality of SOC values, a second impedance of the battery at a second frequency higher than the first frequency is measured. In the diagnosis method, determination concerning the state of the battery is performed based on the measurement results of the first impedance and the second impedance for the target SOC value.