Electrified Vehicle Drivetrain Intermittent Ground Fault Detection
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Solution Overview
Problem
Traditional ground fault detection systems in electrified vehicles are ineffective in detecting intermittent ground faults, which can occur due to harsh environmental conditions such as vibration, temperature changes, and debris, leading to potential undetectable faults that may cause major issues.
Innovation Solution
A control system and method that continuously monitors the potential between high-voltage cables and the chassis, using a controller to selectively open traction battery contactors based on amplitude thresholds and frequency domain analysis to detect and respond to intermittent ground faults, thereby disconnecting the traction battery from high-voltage components and transitioning to an internal combustion engine if necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional ground fault detection systems are used, then the system structure is simple, but intermittent ground faults cannot be detected
Solution Approach 1:
The system dynamically adjusts its detection strategy based on vehicle operating conditions. The controller monitors potential differences continuously and adapts the response threshold and duration based on whether the vehicle is moving or stationary, enabling reliable detection of intermittent faults without requiring overly complex fixed-threshold systems
Solution Approach 2:
The system performs preliminary monitoring and evaluation of potential differences before triggering a fault condition. By measuring the duration and magnitude of potential excursions in advance, the system can distinguish between transient noise and actual intermittent ground faults, improving detection reliability without immediate system shutdown
2Reliability
If the controller opens contactors for any potential threshold exceedance, then safety is improved, but false alarms increase due to transient fluctuations
Solution Approach 1:
The system uses periodic monitoring of potential differences with defined measurement intervals and duration thresholds. By requiring the potential to exceed the threshold for a specific duration (e.g., multiple consecutive measurement cycles) before triggering contactor opening, the system filters out transient fluctuations while maintaining safety response to genuine faults
Solution Approach 2:
The controller continuously monitors the potential difference between high-voltage cables and chassis and uses this feedback to adjust its response. The system evaluates both the magnitude and duration of potential excursions, and only opens contactors when the feedback indicates a sustained fault condition rather than a transient spike, reducing false alarms while maintaining safety
3Use of energy by moving object
If the vehicle operates in high-voltage electric mode, then energy efficiency is improved, but vulnerability to ground faults increases
Solution Approach 1:
The system implements protective monitoring that detects intermittent ground faults before they can cause major damage or safety incidents. By continuously measuring potential differences and identifying patterns of intermittent faults early, the system can take preventive actions such as opening contactors or alerting the driver, cushioning against the harmful effects of ground faults while allowing normal high-voltage operation
Solution Approach 2:
The controller acts as an intermediary between the high-voltage electric system and the low-voltage control system. It monitors the high-voltage system for ground faults and mediates the response by selectively opening contactors or transitioning to hybrid mode, protecting the energy-efficient electric operation from ground fault susceptibility while maintaining overall system safety
Data Source
AI summary
A control system for a vehicle includes a controller. The controller is configured to open traction battery contactors based on a potential between high-voltage cables and a chassis continuously exceeding an amplitude threshold for at least a predefined duration of time. The controller is further configured to selectively open the contactors based on data derived from the potential for periods that are each defined by the potential exceeding and then falling below the amplitude threshold without exceeding the predefined duration of time.