Battery Remaining Capacity Estimation Using Voltage-Corrected Current Integration
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Solution Overview
Problem
Conventional methods for estimating the remaining capacity of high-voltage batteries in hybrid and fuel cell vehicles are inaccurate, leading to potential overcharging or over-discharging, which can cause dangerous situations due to errors in current integration and voltage measurement methods.
Innovation Solution
A method that measures current, voltage, and temperature, corrects the current value based on voltage, calculates a current integration capacity while reflecting charge/discharge efficiency, determines if correction is needed using a forward voltage capacity, and selectively corrects the current integration capacity to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current integration method is used to calculate remaining capacity, then calculation speed is fast, but accuracy deteriorates due to sensor errors and cumulative integration errors
Solution Approach 1:
The patent applies feedback by continuously monitoring the deviation between current integration capacity and forward voltage capacity, then using this deviation to correct the initial state of charge (SOC) value. This closed-loop feedback mechanism eliminates cumulative integration errors and sensor errors while maintaining calculation efficiency, directly resolving the accuracy-complexity contradiction.
Solution Approach 2:
The patent replaces the purely electrical current integration method with a hybrid approach that incorporates electrochemical principles (forward voltage calculation based on open circuit voltage and capacity relationships). This substitution introduces a more accurate physical model that compensates for sensor errors and integration drift without significantly increasing computational complexity.
2Measurement precision
If forward voltage capacity calculation is performed continuously to correct errors, then accuracy improves, but computational load increases
Solution Approach 1:
The patent implements periodic correction by calculating forward voltage capacity at specific intervals or under specific conditions (such as when deviation exceeds a threshold) rather than continuously. This periodic action maintains accuracy by correcting errors when they become significant while minimizing unnecessary computational energy consumption during normal operation.
Solution Approach 2:
The patent dynamically adjusts the correction frequency and threshold parameters based on operating conditions such as current rate, temperature, and battery state. By changing these parameters adaptively, the system optimizes the balance between accuracy and computational energy consumption, performing intensive calculations only when necessary.
3Measurement precision
If initial SOC value is incorrectly estimated, then subsequent remaining capacity calculations diverge from actual values, but correcting initial SOC requires additional measurement precision
Solution Approach 1:
The patent performs preliminary forward voltage capacity calculation before final remaining capacity determination to verify and correct the initial SOC value. This preliminary action ensures that subsequent calculations are based on an accurate initial state, preventing divergence over time and enhancing long-term reliability without requiring additional external measurements.
Solution Approach 2:
The patent uses feedback from the comparison between current integration capacity and forward voltage capacity to continuously refine the initial SOC estimate. This feedback mechanism detects and corrects initial SOC errors dynamically, ensuring calculation reliability is maintained throughout the battery's charge-discharge cycles.
Data Source
AI summary
The present invention provides a technique for estimating a remaining capacity of a battery. In particular, the technique measures a current value, a voltage value and temperature of the battery and corrects the current value based on the voltage value. The corrected current value is then integrated and the result is used to calculate a current integration capacity by reflecting a charge/discharge efficiency accordingly. A battery forward voltage capacity is then determined from the measured current value, voltage value and temperature, and used to determine whether it is necessary to correct the current integration capacity. The current integration capacity is then converted into a remaining capacity, if it is determined that a correction is not necessary. If it is determined that a correction is necessary, the current integration capacity is corrected and then the corrected current integration capacity is converted into a remaining capacity.