Voltage Sensor Fault Isolation in Hybrid Electric Vehicle Electrical Systems
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Solution Overview
Problem
In hybrid electric and battery electric vehicles, voltage sensors used to detect faults in contactors can fail, complicating the diagnosis and isolation of stuck-in-range voltage sensor and welded contactor faults, as they rely on accurate voltage measurements which are compromised by faulty sensors.
Innovation Solution
A method and system that utilize a voltage sensor to measure voltage between a ground and a conductive rail in an electrical system, with a controller comparing the measured voltage to a threshold to record diagnostic codes for stuck-in-range voltage sensor, stuck-closed contactor, and shorted faults, allowing for the isolation of voltage sensor failures from contactor failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If voltage sensors are used to detect contactor faults, then fault detection capability is improved, but diagnostic reliability deteriorates when the voltage sensor itself fails
Solution Approach 1:
The patent introduces an intermediary diagnostic method that uses the known operational states of the contactor (open/closed) as a reference to validate voltage sensor readings. By comparing expected voltage values (based on contactor state) with actual sensor readings, the system can detect both contactor faults and voltage sensor faults, resolving the reliability issue when sensors fail.
2Reliability
If contactors are used to isolate battery pack, then electrical isolation is improved, but system complexity increases due to fault diagnosis requirements
Solution Approach 1:
The patent enables the diagnostic system to self-diagnose by automatically comparing voltage readings with expected values based on contactor state, and autonomously identifying faults without requiring external diagnostic equipment or complex manual testing procedures.
Data Source
AI summary
A method for isolating voltage sensor errors from contactor errors in an electrical system includes measuring a voltage between ground and a voltage bus rail when a contactor is open, and comparing the measured voltage to a first threshold voltage corresponding to a calibrated voltage reading that is expected when the contactor is closed. A first diagnostic code is recorded with a stuck-in-range status for the sensor when the measured voltage is greater than 0 and less than the first threshold voltage. A second diagnostic code is recorded with a stuck-closed status for the contactor when the measured voltage is equal to the first threshold voltage. The measured voltage may be compared to a second threshold voltage that exceeds the first threshold voltage, with a third diagnostic code recorded with a shorted value for the sensor when the measured voltage exceeds the first threshold voltage or is less than 0.