Battery Cell Internal Resistance Screening for Undervoltage Faults
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Solution Overview
Problem
Battery packs suffer from reduced output and safety risks due to undervoltage defective battery cells, which are not efficiently detected in existing systems, leading to potential short-circuits and safety hazards in energy storage systems.
Innovation Solution
A battery management system (BMS) that calculates internal resistance values for each battery cell after charging or discharging, detects cells with the highest resistance, and determines defective cells based on repeated occurrences, triggering an alarm for early detection and prevention of safety issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional voltage monitoring is used to detect defective battery cells, then the detection method is simple, but the detection precision is insufficient and cannot identify undervoltage defective cells in early stage
Solution Approach 1:
The patent changes the detection parameter from simple voltage monitoring to internal resistance measurement. By calculating internal resistance values at different states of charge and comparing them across multiple charge-discharge cycles, the system can identify defective cells with higher precision before they cause safety issues or output degradation.
Solution Approach 2:
The system performs preliminary detection by measuring internal resistance during normal charge-discharge operations before defective cells develop into critical failures. This early detection approach allows identification of cells with abnormal resistance characteristics before they cause short-circuits or safety hazards.
2Reliability
If undervoltage defective battery cells are not detected early, then the battery pack continues to operate, but output degradation occurs and safety hazards arise
Solution Approach 1:
The system implements feedback by continuously monitoring internal resistance values during charge-discharge cycles and comparing them against reference values. When abnormal resistance patterns are detected across multiple cycles, the system provides feedback to identify and isolate defective cells, preventing both safety hazards and output degradation.
Solution Approach 2:
By performing preliminary internal resistance measurements during normal operation, the system identifies defective cells before they cause safety issues or productivity loss. This proactive approach maintains both reliability and productivity by enabling early intervention.
3Measurement precision
If internal resistance measurement is performed continuously, then defective battery cells can be detected early, but energy consumption increases
Solution Approach 1:
The system performs internal resistance measurements periodically during normal charge-discharge cycles rather than continuously. By measuring at specific intervals and comparing results across multiple cycles, the system achieves high detection precision while minimizing additional energy consumption, as the measurements are integrated into existing operational cycles.
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
The BMS effectively detects undervoltage defective battery cells early, preventing output degradation and safety hazards, ensuring efficient operation and safety of battery packs in energy storage systems.
Implementation Method 1
an internal resistance value calculation module configured to calculate an internal resistance value for each battery cell directly after each time the battery pack is charged or discharged
Data Source
AI summary
A battery pack in accordance with an embodiment may include a battery management system (BMS) controlling the battery pack, the BMS includes an internal resistance value calculation module calculating an internal resistance value for each battery cell directly after the battery pack is charged or discharged for a predetermined time, a maximum internal resistance valued battery cell detection module detecting a battery cell having a biggest internal resistance value of the calculated internal resistance values, and a defective battery cell determination module determining a defective battery cell on the basis of a detected number of time each battery cell has the biggest internal resistance value.