Battery Charging Time Estimation Using SOC and Internal Resistance
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Solution Overview
Problem
Existing methods for estimating the charging time of secondary batteries are inaccurate due to variations in charging current, temperature, and deterioration, leading to discrepancies between estimated and actual charging times, which can confuse users.
Innovation Solution
A method and apparatus that estimate charging time by measuring battery parameters such as voltage, current, and temperature to calculate internal resistance, and use SOC-OCV data to determine the time lengths of constant current and voltage charging sections, accurately estimating charging time in units of SOC steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If charging time is estimated by dividing battery capacity by charging injection current, then calculation is simple, but accuracy deteriorates due to current variations
Solution Approach 1:
The charging process is divided into multiple time intervals, with each interval having its own charging current measurement. The total charging time is calculated by summing the time required for each interval, where each interval's time is determined by dividing the capacity increment by the measured charging current for that interval. This segmentation allows the estimation to account for current variations while maintaining calculation feasibility.
Solution Approach 2:
The charging current is treated as a dynamic variable that changes over time rather than a constant value. The method measures the charging current at multiple time points during the charging process and uses these time-varying current values to calculate the charging time for each interval, thereby adapting to the dynamic nature of battery charging characteristics.
2Device complexity
If charging time estimation does not account for temperature and deterioration, then calculation is simple, but reliability deteriorates due to actual vs. displayed time differences
Solution Approach 1:
The method performs preliminary measurements of battery parameters including temperature and charging current at the beginning of the charging process. These preliminary data are used to establish the initial state of the battery and to select appropriate charging parameters. By capturing the initial temperature and current conditions, the method prepares the necessary information to account for temperature and deterioration effects without requiring continuous complex monitoring throughout the entire charging process.
Solution Approach 2:
The method continuously monitors battery parameters during charging and uses this feedback information to adjust the charging time estimation. By measuring temperature and current at multiple intervals and comparing actual charging progress with predicted progress, the method can correct estimation errors and improve reliability. The feedback loop allows the system to adapt to actual battery behavior including temperature changes and deterioration effects.
Data Source
AI summary
A method of estimating a charging time of a battery, includes: estimating an SOC of the battery by measuring at least one parameter of the battery; estimating an internal resistance of the battery based on the at least one parameter of the battery, the SOC of the battery, and SOC-OCV data; estimating a time length of a constant current (CC) charging section based on the SOC, the internal resistance, and the at least one parameter of the battery; and estimating a time length of a constant voltage (CV) charging section based on the SOC, the internal resistance, and the at least one parameter of the battery. The estimating of the time length of the CV charging section includes: estimating a charging current of the battery in a unit of an SOC step; and calculating the time length of the CV charging section in the unit of the SOC step.