Battery SOC Estimation Using Historical Capacity Correction
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Solution Overview
Problem
The estimation of the state of charge (SOC) of a battery is inaccurate due to the use of an inaccurate capacity-temperature table, which affects the accuracy of ampere-hour integral calculations.
Innovation Solution
The method involves obtaining the maximum available capacity of the battery from historical complete charging and discharging periods, calculating a historical maximum available capacity, and using a difference value to determine a target capacity, which is then used in ampere-hour integral calculations to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a capacity-temperature table is used to determine available capacity, then the calculation process is simple, but the accuracy of SOC estimation deteriorates when the table is inaccurate
Solution Approach 1:
The patent implements feedback by comparing the available capacity calculated from the capacity-temperature table with the actual available capacity obtained through ampere-hour integral calculation. The difference between these two values is used to correct and update the capacity-temperature table, creating a closed-loop system that continuously improves accuracy while maintaining computational simplicity.
Solution Approach 2:
The patent changes the parameter approach by transitioning from using fixed capacity-temperature table values to dynamically updating these values based on actual battery performance data. The capacity-temperature table is updated with corrected values derived from comparing table lookup results with ampere-hour integral calculations, thereby adapting the parameter to actual conditions.
2Measurement precision
If historical data is used to calculate maximum available capacity, then the accuracy of SOC estimation is improved, but the device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing capacity-temperature table values and historical maximum available capacity data before they are needed for SOC estimation. This allows the system to use pre-processed information rather than performing complex real-time calculations, thereby improving accuracy without significantly increasing operational complexity.
Solution Approach 2:
The patent uses copying by creating a corrected capacity-temperature table that replicates the original table structure but with updated values derived from historical data and ampere-hour integral calculations. This copied table can then be used for future SOC estimations without requiring the complex data processing to be performed repeatedly.
Data Source
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AI summary
A method for estimating an SOC of a battery and a related apparatus. The method includes: obtaining a current value of the battery at a current moment, obtaining maximum available capacities corresponding to at least one complete charging and discharging period of the battery before the current moment, and calculating a historical maximum available capacity of the battery according to the maximum available capacities corresponding to various complete charging and discharging periods; calculating a difference value between the historical maximum available capacity and a current maximum available capacity, and taking the historical maximum available capacity as a target capacity if the difference value is greater than a preset difference threshold; or alternatively, taking the current maximum available capacity as the target capacity if the difference value is not greater than the preset difference threshold; and taking the target capacity as an available capacity of the battery at the current moment, and performing an ampere-hour integral calculation to obtain an estimation value of the SOC of the battery at the current moment. According to the aforementioned solutions, in the present application, when the current maximum available capacity of the battery has lower accuracy, the historical maximum available capacity, which is determined by using historical data, is used to determine the target capacity. Thus, the accuracy of calculation of the SOC is improved.