Battery SOH Estimation Using dV/dQ Features and a 2D-LUT
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Solution Overview
Problem
Existing battery state of health (SOH) estimation methods for lithium-ion batteries are time-consuming, temperature-dependent, and require significant computational effort, making them unsuitable for all cell chemistries and impractical for real-time applications.
Innovation Solution
A method and apparatus utilizing charge-discrete charge-derivative voltage (dV/dQ) analysis, combined with a 2D-Look-Up-Table (2D-LUT), to estimate SOH by detecting features in dV/dQ and average temperature, allowing for quick and accurate estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Coulomb-Counting method is used for direct measurement of capacity, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent applies partial action by using only a portion of the full discharge process. Instead of requiring complete discharge to cutoff voltage, the method uses a truncated discharge curve combined with dV/dQ analysis to extract sufficient information for SOH estimation, significantly reducing the time required while maintaining accuracy
Solution Approach 2:
The patent replaces the mechanical/time-intensive full discharge measurement with a computational approach using differential voltage analysis. By substituting physical discharge time with mathematical processing of voltage-current relationships, the system achieves rapid SOH estimation without waiting for complete battery discharge
2Measurement precision
If DVA-based SOH-estimation method is used, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts only the essential features from the complex DVA methodology. By focusing specifically on the dV/dQ relationship and its peaks during discharge, the method isolates the critical information needed for SOH estimation while discarding unnecessary computational complexity and filtering requirements
Solution Approach 2:
The patent segments the complex DVA process into manageable components: calculating dV/dQ from measured data, identifying peak positions and characteristics, and using these segmented features for SOH estimation. This segmentation reduces the overall computational burden while preserving measurement precision
3Ease of operation
If SOC-OCV relationship method is used, then ease of operation is improved, but adaptability worsens
Solution Approach 1:
The patent creates a universal SOH estimation method that works across different battery chemistries. By using dV/dQ analysis during discharge - a process that exhibits characteristic peaks for various chemistries including LFP, NMC, and NCA - the method achieves broad adaptability while maintaining operational simplicity through standardized measurement and calculation procedures
Data Source
AI summary
An apparatus for battery state of health (SOH) estimation, including: a DV-calculation unit (200) configured for calculating charge-derivative voltage dV/dQ according to operating parameters of a battery, and filtering the charge-derivative voltage dV/dQ; a feature detection unit (300) configured for performing a peak and threshold detection based on the filtered charge-derivative voltage dV/dQ to detect feature which fulfills requirements defined by a typical SOC range and height interval of a center graphite peak, and calculating an average temperature of the battery during a time interval corresponding to the detected feature; an estimation unit (400) configured for performing a SOH-estimate through a 2D-Look-Up-Table (2D-LUT) based on the detected feature and the average temperature.