Battery DC Resistance Estimation Using Temperature Component Separation
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Solution Overview
Problem
Existing methods for estimating the DC resistance value of deteriorated secondary batteries are limited by their reliance on temperature coefficients, failing to accurately account for both temperature-independent and temperature-dependent components, which affects the accuracy of battery state estimation.
Innovation Solution
A battery state estimation apparatus calculates the measured DC resistance value based on current and voltage changes, separating it into non-temperature dependent and temperature dependent components using a constant calculation unit that employs methods like sequential least squares to determine these components accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature coefficient based on the Arrhenius equation is used to correct the resistance value, then the temperature-dependent component of DC resistance can be estimated, but the temperature-independent component cannot be accurately separated, reducing overall estimation accuracy
Solution Approach 1:
The patent segments the DC resistance value into two distinct components: a temperature-independent component (Ra) and a temperature-dependent component (Rb). This segmentation is achieved through a constant calculation unit that separates these components using mathematical relationships, allowing each to be estimated independently and accurately without requiring complex temperature correction models.
2Measurement precision
If only temperature correction methods are used, then the temperature-dependent resistance changes can be accounted for, but the overall DC resistance value after deterioration cannot be accurately estimated due to ignoring temperature-independent changes
Solution Approach 1:
The patent employs a dynamic estimation approach where the constant calculation unit continuously updates the temperature-independent constant (Ra) and temperature-dependent function (Rb) based on measured DC resistance values and temperatures. This dynamic adaptation allows the system to accurately track battery deterioration over time while maintaining accuracy across varying temperature conditions, making the method both precise and broadly applicable.
Data Source
AI summary
A battery state estimation apparatus calculates a measured DC resistance value of a DC resistance based on a current change amount and a voltage change amount, which are calculated in a predetermined period using measured current value and voltage value. The battery state estimation apparatus further calculates (i) a non-temperature dependent constant and (ii) a constant of a temperature dependent function based on (i) an estimated DC resistance value and (ii) the measured DC resistance value. The estimated DC resistance value is an estimated value of the measured DC resistance value; the estimated DC resistance value is represented as a sum of (i) the non-temperature dependent constant Ra, which indicates a temperature independent component of the DC resistance of the secondary battery, and (ii) the temperature dependent function Rb, which indicates a temperature dependent component of the DC resistance of the secondary battery.