Battery Cell Soft-Short Detection Using Voltage Slope Deviation
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Solution Overview
Problem
Current methods for diagnosing self-discharging in battery cells due to internal soft shorts are inefficient, requiring vehicles to be parked for extended periods, which is infrequent and difficult to manage.
Innovation Solution
An apparatus and method for detecting soft shorts in battery cells, involving periodic voltage measurements, determination of voltage slopes and deviations, and detection of battery cells with soft shorts based on threshold conditions, allowing for accurate diagnosis even when the vehicle is not parked for a long time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage measurements are taken periodically with normal sensitivity (2mV threshold), then the measurement system operates with standard sensitivity, but it takes a long time (e.g., 100 hours for 3mV drop) to detect significant voltage drops caused by soft shorts
Solution Approach 1:
The patent changes the measurement parameter from absolute voltage to voltage slope (rate of change). By monitoring how quickly voltage changes over time rather than just the voltage value itself, the system can detect soft shorts much earlier. The controller calculates voltage slopes between consecutive measurements and compares them to reference slopes, enabling detection of abnormal discharge rates before significant voltage drops occur.
Solution Approach 2:
The system performs preliminary measurements during vehicle operation to establish baseline voltage slopes for each battery cell. These reference slopes are stored and used for comparison during diagnostic mode. By having this preliminary data ready, the system can quickly identify deviations indicating soft shorts without needing to wait for significant voltage drops to manifest.
2Reliability
If the vehicle is maintained parked for a long time to diagnose self-discharging, then soft shorts can be detected, but this requires significantly low frequency events (long-term parking) which are infrequent and difficult to manage
Solution Approach 1:
The patent implements a dynamic diagnostic system that adapts its operation mode based on vehicle usage. The controller can operate in normal mode during vehicle use, continuously monitoring voltage slopes, and switch to diagnostic mode when parking is detected. This eliminates the need to deliberately park vehicles for extended periods, as the system can detect soft shorts during regular operation or immediately upon parking.
Solution Approach 2:
The system continuously monitors voltage slopes and provides feedback to the controller, which compares current slopes against reference slopes and historical data. When deviations exceed thresholds, the system generates alerts or diagnoses soft shorts. This continuous feedback mechanism enables real-time detection without requiring scheduled long-term parking events.
3Measurement precision
If multiple voltage measurements and slope calculations are performed, then detection accuracy improves, but the computational complexity and processing requirements increase
Solution Approach 1:
The patent segments the detection process into distinct operational modes: normal operation mode for baseline data collection and continuous monitoring, and diagnostic mode for detailed analysis. Each mode performs specific calculations appropriate to its purpose. The controller divides battery cells into groups and performs measurements in stages, reducing the computational burden compared to analyzing all cells simultaneously with full diagnostic algorithms.
Data Source
AI summary
An apparatus for detecting soft shorts of a battery cell and a method for the same are provided. The apparatus includes a sensor to measure voltages of a plurality of battery cells, and a controller to determine a slope of a voltage of each battery cell, the deviation of the slope of the voltage for each battery cell, and detect a battery cell, which has the soft shorts, of the plurality of battery cells, based on the slope and the deviation.