Battery Parameter Estimation Using Warburg Impedance Approximation
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Solution Overview
Problem
Conventional battery parameter estimation methods using equivalent circuit models face challenges in increasing accuracy due to high computation loads, especially when attempting to estimate parameters in second-order or higher models, which complicates the estimation process.
Innovation Solution
The proposed apparatus and method estimate battery parameters by approximating the Warburg impedance using an n-th order Foster or Cauer equivalent circuit model, reducing the number of parameters to be estimated by using diffusion resistance and capacitance, thereby reducing computation load and improving estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an equivalent circuit model with increased number of resistors or capacitors is used to increase accuracy, then estimation accuracy is improved, but computation load increases
Solution Approach 1:
The patent changes the parameter representation by introducing Warburg impedance elements (diffusion resistance Rd and diffusion capacitance Cd) instead of using traditional Foster-type RC ladder circuit parameters. This parameter transformation allows the system to maintain high estimation accuracy while reducing computation load, as the Warburg impedance model requires fewer parameters to be estimated.
Solution Approach 2:
The patent extracts and separates the diffusion impedance characteristics from the overall battery model by specifically modeling the Warburg impedance component. This extraction allows the diffusion-related parameters (Rd and Cd) to be estimated independently, reducing the total number of parameters that need to be computed while maintaining accuracy for diffusion-dominated frequency ranges.
2Measurement precision
If a second order or higher equivalent circuit model is used to increase accuracy, then estimation accuracy is improved, but it becomes difficult to perform estimation due to increased complexity
Solution Approach 1:
The patent transforms the estimation problem by changing from estimating multiple RC pair parameters in high-order Foster models to estimating only two key parameters (Rd and Cd) in the Warburg impedance model. This parameter simplification makes second-order or higher modeling feasible while maintaining estimation accuracy.
Solution Approach 2:
The patent segments the battery impedance into distinct components, specifically separating the diffusion impedance (Warburg element) from other impedance components. This segmentation allows focused estimation of diffusion parameters without needing to simultaneously estimate all parameters in a complex high-order model, thereby improving estimation feasibility.
Data Source
AI summary
An apparatus and method for battery parameter estimation estimate the parameters of a battery equivalent circuit model while reducing the computation load. The apparatus includes a charge/discharge current detector (3) that detects a charge/discharge current value of a battery (1); a terminal voltage detector (2) that detects a terminal voltage value of the battery (1); and an estimator (4) that estimates, based on the charge/discharge current value and the terminal voltage value, parameters in a battery equivalent circuit model (41) that approximates the Warburg impedance of the battery (1).