Battery Module Weld Inspection Using High-Frequency AC Impedance
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Solution Overview
Problem
Conventional methods for detecting welding defects in battery modules require large-capacity chargers/dischargers and lengthy charging and discharging processes, making them inefficient and economically burdensome, especially with increasing battery capacities.
Innovation Solution
A welding inspection apparatus that applies alternating current to battery modules using a smaller capacity equipment, measuring impedance and resistance values to rapidly detect defects by analyzing the real part of impedance using a high-frequency band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If DC resistance measurement method is used to detect welding defects, then measurement precision is improved, but loss of time increases and device complexity increases
Solution Approach 1:
The patent changes the measurement parameter from DC resistance to AC impedance at high frequencies (10 kHz to 100 kHz). By applying alternating current and measuring impedance magnitude and phase, the system achieves welding defect detection with significantly reduced measurement time while maintaining precision through multi-frequency analysis
Solution Approach 2:
The patent employs periodic alternating current excitation at multiple frequencies to measure impedance characteristics. This periodic action enables rapid detection of welding defects by analyzing the frequency-dependent impedance response, reducing the time required compared to conventional DC measurement methods
2Measurement precision
If high current charging and discharging is used to measure resistance, then measurement precision is improved, but use of energy increases and loss of time increases
Solution Approach 1:
The patent changes from high-current DC measurement to low-current AC impedance measurement at high frequencies. This parameter change reduces energy consumption significantly while maintaining measurement precision through the use of impedance magnitude and phase information obtained from alternating current excitation
3Productivity
If the number of parallel connections in a bank increases, then productivity is improved, but difficulty of detecting and measuring increases
Solution Approach 1:
The patent measures impedance of each bank independently by applying alternating current to each bank separately. This segmentation approach enables detection of welding defects in individual banks even when multiple banks are connected in parallel, reducing the difficulty of detection as the number of parallel connections increases
Solution Approach 2:
The patent uses AC impedance measurement at high frequencies with phase angle analysis to detect welding defects. This parameter change enables effective detection in banks with multiple parallel connections by identifying abnormal impedance characteristics and phase shifts that indicate welding defects, regardless of the number of parallel connections
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
Reduces the need for large-capacity chargers/dischargers and significantly shortens detection time while enabling precise identification of welding defects within battery modules.
Implementation Method 1
an alternating current application unit (310) for applying an alternating current to an entirety of the battery module (330)
Implementation Method 2
a measurement unit (320) for measuring an impedance of each of the banks (332)
Data Source
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AI summary
The present invention relates to a welding inspection apparatus for battery modules capable of applying alternating current to a bank constituted by two or more battery cells connected in parallel and a battery module constituted by one or more banks connected in series to calculate impedance and the resistance value of each of the banks and a method of inspecting welding of the battery module using the same.