Battery SOH Estimation Using SOC Change and Temperature Weighting
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Solution Overview
Problem
Existing battery State of Health (SOH) estimation methods, such as the ampere counting method, are inefficient and prone to inaccuracies due to temperature variations, discharging rates, and sensor offset changes.
Innovation Solution
A battery SOH estimating apparatus and method that corrects the estimated SOH based on the State of Charge (SOC) change amount, SOC change region, and battery temperature, using a weight calculation that considers these factors to improve estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the ampere counting method is used to estimate battery SOH, then the estimation can be performed continuously during battery operation, but the estimation accuracy deteriorates due to temperature variations, discharging rate changes, and current sensor offset drift
Solution Approach 1:
The patent implements a feedback mechanism by comparing the ampere counting method's SOH estimation with an open-circuit voltage (OCV) based estimation method. The system periodically performs full charge-discharge cycles to obtain accurate reference SOH values, then uses these references to correct and calibrate the continuous ampere counting estimations, thereby compensating for accumulated errors from temperature variations and sensor drift
Solution Approach 2:
The patent changes the estimation parameters by introducing temperature compensation factors and discharging rate correction coefficients. The system adjusts the ampere counting method's parameters based on measured temperature and current discharge rates, dynamically modifying the estimation calculations to maintain accuracy under varying operating conditions
2Measurement precision
If full charge and full discharge are performed to estimate battery SOH accurately, then the SOH estimation accuracy is improved, but the time consumption and operational efficiency deteriorate
Solution Approach 1:
The patent applies partial action by performing only necessary portions of full charge-discharge cycles at optimized intervals rather than complete cycles continuously. The system performs abbreviated calibration cycles that capture sufficient data for accurate SOH estimation without requiring complete depletion and recharging, thereby reducing time loss while maintaining estimation precision
Solution Approach 2:
The system performs preliminary calibration measurements at predetermined intervals and uses these pre-obtained reference values to correct subsequent continuous estimations. By preparing reference data in advance during low-demand periods, the system enables rapid accurate SOH estimation during high-demand operations without requiring time-consuming full cycles at all times
3Ease of operation
If current sensor offset is not corrected, then the system operation is simple, but accumulated errors during ampere counting cause SOH estimation inaccuracy
Solution Approach 1:
The patent implements self-service by enabling the system to automatically detect and correct its own sensor offset errors. The ampere counting system periodically compares its measurements with OCV-based reference measurements and automatically calculates and applies offset corrections without requiring manual calibration or external intervention, thereby maintaining both operational simplicity and measurement precision
Data Source
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.