Battery Cell Fault Detection Using Adaptive Voltage Scatter
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Solution Overview
Problem
Existing methods for detecting faults in battery cells, particularly in high-voltage batteries for motor vehicles, face challenges in accurately identifying cell defects early due to varying voltage spreads caused by environmental conditions and aging, leading to potential battery fires.
Innovation Solution
A method that registers cell voltages at specific measurement times and calculates a scatter value to assess deviations, allowing for adaptive limiting values based on the operating state, thereby enhancing the detection of fault states by considering the spread of voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed reference value and tolerance range are used for cell voltage monitoring, then the detection method is simple to implement, but cell defects go unnoticed due to large tolerance ranges required to accommodate natural voltage variations
Solution Approach 1:
The patent applies dynamics by transitioning from a static reference value approach to a dynamic reference value approach. The reference value is continuously updated based on the running mean of cell voltages, allowing the monitoring system to adapt to changing operating conditions and natural voltage variations over time. This enables more precise fault detection without requiring overly complex predetermined tolerance ranges.
Solution Approach 2:
The patent implements feedback by using the measured cell voltages to continuously update the reference value through a running mean calculation. This feedback mechanism allows the system to learn from normal operating variations and adjust the reference accordingly, improving detection precision while maintaining relatively simple implementation through iterative adaptation rather than complex predefined rules.
2Reliability
If a large tolerance range is used for cell voltage deviations, then false warnings are avoided, but early cell defects are not detected
Solution Approach 1:
The dynamic reference value updates over time, allowing the system to establish a reliable baseline of normal operation before detecting deviations. This temporal adaptation enables the system to maintain high reliability while reducing the time to detect faults, as the reference value becomes increasingly accurate with each measurement cycle rather than relying on fixed, conservative tolerance ranges.
Solution Approach 2:
The system performs preliminary action by continuously updating the reference value during normal operation before a fault occurs. This preliminary adaptation phase allows the system to learn normal voltage variations and establish an accurate baseline, enabling earlier and more reliable fault detection when actual deviations occur, rather than waiting for large deviations to trigger alerts.
3Measurement precision
If small tolerance ranges are used for cell voltage monitoring, then early defects are detected, but unnecessary warnings are generated due to natural voltage drift
Solution Approach 1:
The feedback mechanism continuously updates the reference value based on actual measured voltages, allowing the system to distinguish between natural voltage drift and actual faults. By comparing deviations against this adaptive reference rather than a fixed value, the system maintains high detection precision while filtering out false warnings caused by normal operating variations.
Solution Approach 2:
The system performs self-service by automatically adapting its own reference value through the running mean calculation without requiring external calibration or manual adjustment. This self-adjusting capability enables the system to maintain high detection precision while automatically compensating for natural voltage variations, reducing false warnings without sacrificing early fault detection.
Data Source
AI summary
A method for detecting a fault state of at least one battery cell of a battery having multiple battery cells. A cell voltage of a respective battery cell of the multiple battery cells is registered at a measurement time and a comparison value is determined as a function of at least one of the cell voltages and is compared to a provided first reference value. The fault state is detected as a function of a result of the comparison. A scatter value is determined, which represents a scatter of at least part of the cell voltages registered at the specific measurement time, and the fault state is determined as a function of the scatter value.