Battery Impedance Screening for Fast Low-Voltage Defect Detection
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Solution Overview
Problem
Existing battery defect inspection methods, particularly for medium or large-sized batteries formed by stacking monocells, are inefficient in detecting low-voltage defects and take a long time, leading to instability and reduced product reliability.
Innovation Solution
A high-speed battery defect inspection method involving impedance measurement, real part resistance extraction, and defect determination using a set frequency selected based on imaginary part resistance greater than 0, allowing for rapid identification of low-voltage defects in batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional battery voltage tracking or HPCD inspection methods are used, then low-voltage defective cells can be detected, but the inspection time is excessively long (2 weeks or more)
Solution Approach 1:
The patent changes the measurement parameter from conventional voltage tracking to impedance measurement at specific frequencies. By measuring impedance at frequencies where the imaginary part is greater than 0 and selecting the frequency where the real part resistance is maximum, the method achieves rapid defect detection within seconds while maintaining detection accuracy through the unique impedance characteristics of defective cells
Solution Approach 2:
The patent replaces the time-consuming voltage tracking method with an electrical impedance measurement method. This substitution enables high-speed inspection by using AC signal application and impedance analysis, reducing inspection time from weeks to seconds while detecting low-voltage defective cells through characteristic impedance patterns
2Productivity
If high-speed impedance measurement is performed, then inspection speed increases to thousands per second, but selecting the appropriate frequency becomes complex
Solution Approach 1:
The patent employs a self-service mechanism where the system automatically identifies the optimal measurement frequency by scanning multiple frequencies and detecting where the imaginary part of impedance is greater than 0. The system then automatically selects the frequency with maximum real part resistance, eliminating the need for manual frequency selection and simplifying the operation while maintaining high inspection speed
Solution Approach 2:
The patent implements feedback control by measuring impedance across multiple frequencies and using the imaginary part as a criterion to identify the appropriate frequency range. The system then uses the real part resistance values to determine the optimal frequency, creating a feedback loop that automatically adapts to different battery conditions and simplifies the measurement process
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
Enables rapid detection of low-voltage defects in batteries, reducing inspection time significantly and enabling non-destructive inspection of thousands to tens of thousands of batteries per second, applicable to mass production lines.
Implementation Method 1
an analysis target impedance measurement step (s30) of obtaining an analysis target impedance which is an impedance of an analysis target battery by applying alternating current of a set frequency to the analysis target battery
Data Source
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AI summary
The present invention relates to a high-speed battery defect inspection method, and, specifically, to a high-speed battery defect inspection method for determining, in a short time, whether a battery formed by stacking a plurality of monocells is defective, by predicting the degradation characteristics of the battery.