Battery Performance Evaluation Using Impedance and OCV Thresholds
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Solution Overview
Problem
Existing methods for evaluating secondary battery performance, such as the alternating current impedance measurement method, face reduced accuracy when the state of charge (SOC) is not adjusted, as batteries with defects like micro-short circuits are misclassified, affecting the evaluation of battery deterioration and reuse decisions.
Innovation Solution
A battery performance evaluation device that measures alternating current impedance and open circuit voltage, estimating SOC to be 0% based on threshold values for the imaginary component of impedance and voltage, allowing for accurate classification and capacity estimation, even without adjusting SOC, using a pre-trained neural network model for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If alternating current impedance measurement is performed without adjusting SOC, then measurement process is simplified, but evaluation accuracy deteriorates due to misclassification of batteries with defects
Solution Approach 1:
The patent introduces an intermediary classification process that uses multiple measurement parameters (alternating current impedance imaginary component, open circuit voltage, and charge/discharge characteristics) to accurately distinguish between batteries with SOC=0% and those with defects like micro-short circuits. This intermediary classification step resolves the contradiction by enabling accurate evaluation without requiring SOC adjustment, thus maintaining measurement simplicity while improving accuracy.
2Productivity
If SOC adjustment is eliminated to simplify the process, then productivity increases, but reliability decreases due to inclusion of defective batteries in evaluation
Solution Approach 1:
The patent applies preliminary action by performing classification based on multiple parameters (imaginary component, OCV, and charge/discharge characteristics) before the final capacity evaluation. This preliminary classification separates batteries with SOC=0% from those with defects, ensuring that only suitable batteries undergo further evaluation. This approach maintains high productivity by avoiding SOC adjustment while ensuring reliable evaluation results.
3Measurement precision
If multiple parameters are used for classification, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent implements universality by using a single evaluation system that measures multiple parameters (alternating current impedance, open circuit voltage, and charge/discharge characteristics) through integrated measurement processes. The evaluation device performs classification and capacity estimation using these multiple parameters without requiring separate specialized equipment, thus improving classification accuracy while avoiding excessive device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the accuracy and efficiency of battery performance evaluation by correctly identifying SOC and capacity, enabling better decision-making for battery reuse and recycling, with optimized neural network training for specific battery types and conditions.
Implementation Method 1
an alternating current impedance acquiring process of acquiring a measurement result of an alternating current impedance of a target secondary battery, the alternating current impedance measured by applying an application signal to the target secondary battery within a specific frequency range
Implementation Method 2
an open circuit voltage (OCV) acquiring process of acquiring an OCV of the target secondary battery
Data Source
AI summary
A battery performance evaluation device executes an alternating current impedance acquiring process (S1), an OCV acquiring process (S2), and an SOC estimating process (S3). The alternating current impedance acquiring process involves acquiring a measurement result of an alternating current impedance of a target secondary battery, the alternating current impedance measured by applying an application signal to the target secondary battery within a specific frequency range. The OCV acquiring process involves acquiring an OCV of the target secondary battery. The SOC estimating process involves estimating an SOC of the target secondary battery to be 0%, if an imaginary component of the measurement result of the acquired alternating current impedance at a predetermined frequency within the specific frequency range is greater than or equal to a first threshold value and the acquired OCV value is less than or equal to a second threshold value.