Battery Cell Diagnosis Using Equivalent Circuit Parameters
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Solution Overview
Problem
Existing battery diagnosis methods are unable to quickly diagnose defects in battery cells within a battery pack, particularly during use, and do not differentiate between different defect types.
Innovation Solution
A battery diagnosis apparatus and method that utilizes an information obtaining unit to collect current and voltage data, and a controller to determine a target period based on current, calculate parameter values using an equivalent circuit model, and diagnose cell states based on these values, allowing for rapid identification of defects and differentiation between defect types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nondestructive testing or pulse response methods are used to diagnose battery state, then battery state can be diagnosed with minimal battery state change, but only degradation degree can be determined and defect diagnosis cannot be completed within a short period of time
Solution Approach 1:
The patent changes the diagnostic parameters from traditional voltage/current response to impedance spectrum parameters (real part and imaginary part of impedance). By analyzing impedance characteristics at different frequencies and time periods, the system can identify specific defect types (short circuit, negative electrode exposure, lithium precipitation) rather than just degradation degree, enabling rapid defect diagnosis during battery use.
Solution Approach 2:
The patent applies partial action by selecting specific time periods (first period and second period) from the impedance spectrum data to diagnose different defect types. Instead of analyzing the entire impedance spectrum, the system focuses on specific time windows that are most indicative of particular defects, enabling rapid diagnosis within a short period while maintaining high accuracy.
2Loss of information
If traditional diagnosis methods are used, then battery degradation can be assessed, but specific defect types cannot be identified and differentiated
Solution Approach 1:
The patent segments the impedance spectrum data into different time periods (first period and second period) and analyzes specific parameters (real part and imaginary part of impedance) in each period. This segmentation allows the system to identify and differentiate specific defect types (short circuit, negative electrode exposure, lithium precipitation) by examining characteristic patterns in different time windows, thereby recovering lost defect type information without requiring overly complex diagnostic equipment.
3Productivity
If battery diagnosis is performed during use, then early defect detection is possible, but existing methods cannot complete defect diagnosis within a short period of time
Solution Approach 1:
The patent applies partial action by focusing analysis on specific time periods (first period and second period) within the impedance spectrum data. This selective analysis of key time windows enables rapid defect diagnosis during battery use while maintaining high precision in identifying specific defect types, resolving the contradiction between fast detection and accurate diagnosis.
Solution Approach 2:
The patent changes from traditional diagnostic parameters to impedance spectrum parameters analyzed at specific time periods. By monitoring real and imaginary parts of impedance during battery operation and comparing them against reference values, the system achieves both rapid defect detection during use and precise identification of specific defect types.
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 diagnosis of battery cell defects and differentiation between defect types, enhancing safety by identifying potential issues before they lead to fires.
Implementation Method 1
calculate at least one parameter value of an equivalent circuit model by using the voltage data of each of the plurality of battery cells
Implementation Method 2
determine, as the analysis period, a period related to a resistance component considering an influence of movement of ions between an electrode interface and an electrolyte solution and a condenser component considering a capacitive effect
Data Source
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Figure 3A
AI summary
A battery diagnosis apparatus includes an information obtaining unit configured to obtain current and voltage data of each of a plurality of battery cells and a controller configured to determine a target period based on a current of each of the plurality of battery cells, calculate at least one parameter value of an equivalent circuit model by using the voltage data of each of the plurality of battery cells, corresponding to the target period, and diagnose a state of each of the plurality of battery cells, based on the at least one parameter value.