Leakage Resistance Detection in Electric Vehicle Battery Systems
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Solution Overview
Problem
Conventional electric vehicles face challenges in detecting electrical leakage paths between the high voltage traction battery and the vehicle chassis, which can lead to short circuits, and existing methods require additional circuits or risk battery discharge when not in use.
Innovation Solution
A vehicle system with a battery pack, electric motor, and contactor, along with control circuitry including a leak voltage detection sensor and controller, estimates leakage resistance between the battery and chassis by measuring battery and leak voltages using a monitoring circuit at the contactors, without requiring additional circuits, thus protecting the battery when not in use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional leakage detection methods are used, then leakage paths can be detected, but additional circuits are required and battery discharge risk increases
Solution Approach 1:
The existing contactor circuit is made to serve dual functions: its primary function of connecting/disconnecting the battery and an additional function of leakage detection. By measuring voltage at the contactor terminals during the closing transition, the system detects leakage without requiring separate detection circuits, thus reducing overall system complexity while maintaining detection capability
Solution Approach 2:
The system uses its own operational characteristics (voltage changes during contactor closing) to perform self-diagnosis for leakage detection. The battery management system leverages normal operational data from the contactor circuit to automatically detect leakage conditions without external intervention or additional dedicated detection infrastructure
2Reliability
If conventional leakage detection methods are used, then leakage paths can be detected, but battery discharge is prevented
Solution Approach 1:
Leakage detection is performed periodically at specific moments (during contactor closing transitions) rather than continuously. This intermittent measurement approach enables leakage detection while minimizing energy consumption, as the system only activates detection functionality when the contactor is transitioning states, naturally reducing battery discharge
Solution Approach 2:
The system performs leakage detection at the moment of contactor closing, which is a predetermined operational event. By timing the detection to coincide with this specific moment in the operational sequence, the system ensures leakage is checked before full power connection occurs, preventing energy loss while maintaining detection effectiveness
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
This method effectively detects and estimates leakage resistance between the traction battery and the vehicle chassis, preventing short circuits and battery discharge, while not needing additional circuits, thus enhancing safety and efficiency.
Implementation Method 1
a leak voltage detection sensor... configured to detect a voltage of the battery pack and a leak voltage
Implementation Method 2
output a leakage resistance between the battery and chassis based on the voltage of the battery pack, the leak voltage, and a leakage current
Data Source
AI summary
A vehicle includes a battery pack, an electric motor, and a contactor to electrically connect the pack and motor. The contactor is configured with a control circuit to electrically connect the pack and motor. The control circuit includes a leak detection sensor. The vehicle further includes a controller to output a leakage resistance associated with the pack. The leakage resistance is based on a voltage of the pack and a leak voltage detected by the sensor while the contactor is closed.