Battery State of Health Determination via Multi-Factor Normalization
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Solution Overview
Problem
Existing battery state of health (SoH) determination methods are limited by their specificity to particular battery types and models, requiring pre-processed test data and not accounting for variations in capacity, nominal voltage, and state of charge (SoC), making them ineffective for diverse battery chemistries and configurations.
Innovation Solution
A method employing multi-dimensional normalization using a discharge current pulse, analyzing the battery's response, and normalizing it based on nominal voltage and initial open circuit voltage (OCV) to determine SoH without prior knowledge of battery chemistry or configuration, allowing for testing of batteries with different capacities and SoC without pre-test data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing battery SoH determination methods are used, then testing is specific to particular battery types and models with pre-processed data, but this limits applicability to diverse battery chemistries and configurations
Solution Approach 1:
The patent applies normalization techniques to create a universal testing method that can determine SoH across different battery chemistries (Li-ion, LiFePO4, LiMn2O4, etc.) and configurations without requiring separate pre-processed data for each battery type. The normalization factors adjust measurements based on battery capacity and voltage, enabling one testing system to handle multiple battery varieties.
Solution Approach 2:
The patent changes the parameters of the testing approach by introducing normalization factors that adjust the discharge pulse current and voltage measurements based on battery capacity and nominal voltage. This transforms a battery-specific testing method into a universal method that adapts to different battery parameters through mathematical normalization rather than separate pre-processing for each battery model.
2Measurement precision
If battery testing accounts for different capacities and nominal voltages, then accuracy improves across diverse batteries, but measurement and analysis complexity increases
Solution Approach 1:
The patent changes the measurement approach by normalizing voltage and current parameters based on battery capacity and nominal voltage. Instead of creating complex battery-specific test protocols, the method applies mathematical normalization factors to the measurements, simplifying the analysis while improving accuracy across different battery types.
Solution Approach 2:
The patent introduces normalization factors as intermediary elements that mediate between the raw battery measurements and the final SoH determination. These factors serve as a bridge that accounts for differences in battery capacity and voltage without requiring complex battery-specific analysis procedures.
3Reliability
If discharge pulse amplitude is normalized to battery capacity, then consistent SoH determination is achieved across different battery sizes, but the testing system complexity increases
Solution Approach 1:
The patent changes the discharge pulse amplitude parameter by normalizing it to battery capacity. Instead of using a fixed discharge current for all batteries, the system adjusts the pulse amplitude based on the battery's capacity rating, ensuring that smaller batteries receive proportionally smaller discharge currents while larger batteries receive proportionally larger currents, achieving consistent SoH determination across different battery sizes.
Data Source
AI summary
A battery is subjected to a discharge current pulse that is normalized to its capacity. The battery voltage is measured before, during and after the pulse, and various parameters are calculated therefrom. The parameters are adjusted depending on both the value of the nominal or maximum cut-off voltage of the battery and on its open circuit voltage prior to the pulse. Based on the open circuit voltage, one of multiple different analysis paths is selected, each representing a different state of charge range. The analysis selected involves a comparison of the adjusted parameters with a set of thresholds that are specific to the selected analysis and that depend on the desired cut-off point between good and poor state of health. Batteries of different nominal voltages, capacities and chemistries can be tested without knowing their state of charge and without the tester having been calibrated for a specific battery model.