Battery Overcurrent Diagnostic System Using Voltage Difference
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Solution Overview
Problem
Current systems for diagnosing and managing overcurrent conditions in vehicle batteries lack effective detection and response mechanisms, leading to potential damage and inefficiency in electric vehicle propulsion systems.
Innovation Solution
A diagnostic system that includes a traction battery with multiple cells and sensors to measure operating parameters, a controller that indicates an overcurrent condition based on current sensor thresholds and voltage differences, and a control strategy to manage the battery by disconnecting from the high voltage bus or reducing power when an overcurrent condition is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If current sensor upper limit is used to detect overcurrent conditions, then detection speed is improved, but measurement precision deteriorates due to sensor saturation at high currents
Solution Approach 1:
The patent introduces voltage as an intermediary parameter to indirectly measure current. By measuring voltage across a known resistance and using the relationship V=IR, the system can determine current values that exceed the direct measurement range of the current sensor, thus resolving the contradiction between detection speed and measurement precision at high current levels
Solution Approach 2:
The patent changes the measurement parameter from direct current measurement to voltage measurement. This parameter transformation allows the system to measure high current values indirectly through voltage, avoiding the saturation problem of current sensors while maintaining fast detection response
2Measurement precision
If voltage difference threshold is set low for sensitive overcurrent detection, then detection accuracy is improved, but false positive rate increases
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors the voltage difference and compares it against the threshold. When the threshold is exceeded, the system provides feedback by triggering an overcurrent condition indication, allowing for continuous adjustment and validation of detection parameters to reduce false positives while maintaining sensitivity
Solution Approach 2:
The system performs preliminary validation by establishing the voltage difference threshold before operation and using it to pre-filter potential overcurrent conditions. This preliminary action allows the system to quickly identify candidates for overcurrent detection while the feedback mechanism validates them to prevent false positives
Data Source
AI summary
A diagnostic system for a vehicle includes a traction battery including a plurality of cells, and a controller configured to indicate an overcurrent condition in response to battery current being greater than a value of an upper limit of a current sensor and a difference between a measured battery voltage and an estimated battery voltage, that is based on the value, being greater than a threshold.