Vehicle High Voltage Interlock Startup Fault Detection
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Solution Overview
Problem
High voltage electrical systems in hybrid-electric and all-electric vehicles face challenges in efficiently detecting faults and ensuring connectivity in traction battery and load connections, which can lead to safety issues and system failures.
Innovation Solution
A controller-programmed testing voltage is applied to the load, using power converters and switches like IGBTs, MOSFETs, and relays to check for faults, and an algorithm is implemented to manage current flow and voltage thresholds to protect the high voltage system, ensuring safe operation by preventing excessive voltage or current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full battery voltage is applied during startup to ensure proper initialization of all high voltage components, then component initialization is reliable, but undetected faults may cause safety hazards and system damage
Solution Approach 1:
The system performs a preliminary low-voltage initialization sequence before applying full battery voltage. The controller initially connects the battery to the DC-DC converter and motor controller at reduced voltage levels to verify proper operation and detect faults. Only after successful preliminary initialization does the system proceed to full voltage operation, ensuring safety while maintaining reliability.
2Object-affected harmful factors
If a comprehensive fault detection system is implemented before system startup to ensure safety, then safety hazards are reduced, but system complexity and initialization time increase
Solution Approach 1:
The fault detection process is integrated into the continuous startup sequence rather than being a separate preliminary step. The controller continuously monitors voltage levels, current flow, and component responses throughout the initialization process. This continuous monitoring approach provides comprehensive safety checks without requiring additional separate detection systems, thereby reducing overall system complexity.
3Object-affected harmful factors
If step-by-step voltage initialization is implemented to ensure safety and detect faults, then system safety is improved, but initialization time increases
Solution Approach 1:
The initialization process uses periodic voltage staging with defined thresholds. The controller applies voltage in discrete steps (e.g., 0V to 50% battery voltage, then to 100% battery voltage) with automated fault checks at each stage. This periodic approach ensures thorough safety verification while maintaining a predictable and optimized initialization timeline, preventing excessive delays.
4Speed
If high voltage is applied immediately upon connector engagement to ensure rapid system readiness, then system readiness speed is improved, but fault detection capability is reduced
Solution Approach 1:
The system performs preliminary low-voltage diagnostics immediately upon connector engagement, before applying full high voltage. The controller checks for proper connector seating, verifies component continuity, and detects any open circuits or short circuits at the lower voltage stage. This preliminary action enables rapid fault detection while maintaining quick system readiness by avoiding delays in the high-voltage application itself.
Data Source
AI summary
A vehicle high voltage system may include switches (e.g., IGBTs, contactors, relays, etc.), wires, a traction battery, electrical components with electrical properties and at least one controller. The at least one controller may be programmed to modulate a switch to provide a testing voltage for the electrical components, which is less than an operating voltage of the battery, and in response to a current flow associated with the testing voltage being less than a predetermined threshold, stop current flow between the battery and electrical components.