Secondary Battery Power Prediction Using Nonlinear Equivalent Circuit Model
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing secondary battery models, particularly those using a single RC circuit, struggle to accurately predict maximum inputtable and outputtable power at low temperatures due to nonlinear changes in current-voltage characteristics, leading to reduced accuracy in power predictions.
Innovation Solution
An equivalent circuit model incorporating a DC resistance model, a reaction impedance model with a nonlinear relationship, and a diffusion impedance model with multiple RC parallel circuits is used to calculate polarization voltages and predict target power parameters, accounting for temperature-dependent nonlinearities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single RC circuit model is used to predict power parameters, then the model structure remains simple, but the prediction accuracy deteriorates in low-temperature regions due to nonlinear current-voltage characteristics
Solution Approach 1:
The equivalent circuit model is segmented into multiple RC parallel circuits (first RC parallel circuit and second RC parallel circuit) connected in series, rather than using a single RC circuit. Each RC circuit captures different time constants and electrochemical processes, enabling accurate representation of nonlinear current-voltage characteristics across varying temperatures while maintaining modular structure
Solution Approach 2:
The model incorporates temperature-dependent parameters where the resistance and capacitance values of each RC circuit are adjusted based on temperature conditions. This allows the model to adapt to nonlinear current-voltage characteristics at low temperatures while maintaining simplicity at higher temperatures, resolving the contradiction between accuracy and complexity
2Reliability
If a single RC circuit model is used, then the model is easy to implement, but the ability to express electrochemical behavior accurately deteriorates when current-voltage characteristics change nonlinearly
Solution Approach 1:
The equivalent circuit model is segmented into multiple RC parallel circuits (first RC parallel circuit and second RC parallel circuit) connected in series, rather than using a single RC circuit. Each RC circuit captures different time constants and electrochemical processes, enabling accurate representation of nonlinear current-voltage characteristics across varying temperatures while maintaining modular structure
Solution Approach 2:
The model dynamically adapts to changing electrochemical behavior by using multiple RC circuits with different time constants that can capture transient responses at various rates. This dynamic capability allows the model to accurately represent electrochemical processes during both steady-state and transient conditions, improving reliability without excessive complexity
Data Source
AI summary
In an apparatus, a circuit model includes a DC resistance model, and a reaction impedance model having a nonlinear relationship between a first potential difference across a reaction resistance and a current flowing through the secondary battery. The nonlinearly relationship depends on a temperature of the secondary battery. The circuit model includes a diffusion impedance model. The apparatus predicts a future remaining voltage across the secondary battery at a future timing when a predetermined duration will have elapsed since a prediction time. The apparatus calculates a future polarization voltage across the secondary battery at the future timing. The apparatus predicts a target power parameter of the secondary battery at the future timing according to the future remaining voltage, the future polarization voltage, a first potential difference across the reaction resistance, and a second potential difference across the DC resistance model.