Battery SOH Estimation Using SOC Region and Temperature Weighting
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Solution Overview
Problem
Existing methods for estimating battery State of Health (SOH) are inaccurate due to errors from current sensor offsets and the need for full charge and discharge cycles, and do not adequately consider temperature and SOC change regions.
Innovation Solution
A battery SOH estimating apparatus and method that corrects SOH estimates based on SOC change amount, region, and temperature, using a weight calculation that combines voltage, current, and temperature factors to refine initial SOH estimates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the ampere counting method is used to estimate SOH, then measurement precision is improved, but productivity deteriorates due to the need for full charge and discharge cycles
Solution Approach 1:
The patent applies partial action by estimating SOH using only a portion of the battery capacity range rather than requiring full charge and discharge. The method calculates SOH based on voltage measurements at specific SOC points (e.g., 30% and 70% SOC) during normal operation, eliminating the need for complete cycling while maintaining estimation accuracy through selective measurement at critical points.
2Measurement precision
If the ampere counting method is used, then measurement precision is improved, but device complexity increases due to current sensor offset changes
Solution Approach 1:
The patent extracts and eliminates the dependency on current sensors by replacing the ampere counting method with a voltage-based SOH estimation method. By measuring only voltage at specific SOC points and using voltage-SOC correlations, the system removes the complex current sensor offset compensation requirements while maintaining estimation precision through alternative measurement principles.
Solution Approach 2:
The patent substitutes the mechanical/electrical current measurement system with an electrical voltage measurement system. Instead of using current sensors and integrating current over time, the method uses voltage measurements combined with voltage-SOC correlation data to estimate SOH, replacing a complex measurement chain with a simpler voltage-based approach.
3Measurement precision
If full charge and discharge cycles are performed, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent applies preliminary action by pre-establishing voltage-SOC correlation data through full charge-discharge cycles during battery manufacturing or initial calibration. This preliminary characterization creates lookup tables or mathematical models that map voltage to SOC. During normal operation, SOH estimation uses only brief voltage measurements at specific points, leveraging the pre-computed correlations to avoid repeated full cycling while maintaining accuracy.
Data Source
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AI summary
A battery SOH estimating apparatus according to an embodiment of the present disclosure includes a SOH estimating unit configured to estimate a first SOH of a battery based on the measured voltage and current of the battery; a SOC change calculating unit configured to calculate a SOC change region and a SOC change amount of the battery based on the measured voltage; a weight calculating unit configured to calculate a weight based on a SOC region factor calculated by comparing the SOC change region with a preset criterion SOC region, a SOC change amount factor based on the SOC change amount, and a temperature factor based on the measured temperature of the battery; and a SOH correcting unit configured to correct the first SOH according to the calculated weight and a preset second SOH.