Fault Detection Device for Vehicle Power Supply Relays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fault detection devices in vehicles often incorrectly identify malfunctions in power supply relays due to abnormalities in other components, leading to unnecessary corrective measures.
Innovation Solution
A fault detection device that distinguishes contact welding faults in power supply relays from abnormalities in the discharge function of capacitors by monitoring voltage changes during controlled discharging processes, preventing inappropriate fail-safe operations and component replacements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fault detection devices monitor power supply relay status to detect contact welding, then reliability of fault detection is improved, but false positive identification increases when other components malfunction
Solution Approach 1:
The fault detection process is segmented into distinct phases: capacitor discharge phase and voltage measurement phase. During the discharge phase, the system actively discharges the capacitor through the motor driver, and during the measurement phase, it measures voltage without active discharge. This temporal segmentation allows the system to distinguish between voltage changes caused by relay contact welding and those caused by capacitor discharge abnormalities.
Solution Approach 2:
The system performs a preliminary capacitor discharge action before conducting the fault detection measurement. By discharging the capacitor through the motor driver in a controlled manner before measuring voltage, the system establishes a known baseline state. This preliminary action enables the subsequent voltage measurement to accurately reflect relay status rather than capacitor state.
2Reliability
If the system initiates fail-safe operations upon detecting relay malfunction, then vehicle safety is improved, but unnecessary corrective measures are taken when false positives occur
Solution Approach 1:
The system uses feedback from voltage measurements taken at specific moments (after capacitor discharge and during idle measurement periods) to determine relay status. The controller continuously monitors voltage and compares it against expected values, providing feedback that confirms whether a detected anomaly represents a true relay fault or a capacitor discharge issue. This feedback mechanism prevents premature fail-safe activation.
Solution Approach 2:
Before initiating fail-safe operations or notifying the driver of relay malfunction, the system performs preliminary diagnostic actions including controlled capacitor discharge and multiple voltage measurements. These preliminary actions verify the nature of the fault, ensuring that fail-safe operations are only triggered when relay contact welding is confirmed rather than when capacitor discharge abnormalities occur.
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
Accurately differentiates between relay faults and capacitor discharge abnormalities, reducing unnecessary repairs and maintaining vehicle functionality by initiating appropriate safety procedures.
Implementation Method 1
a capacitor connected at position between the pair of power supply lines
Implementation Method 2
the discharge of a capacitor by a motor driver
Data Source
AI summary
A fault detection device has a pair of power supply lines connected to a high voltage battery via power supply relays. Capacitors and inverters for driving a motor are disposed between the power supply lines. A controller in the fault detection device controls the inverters to discharge the capacitors at different times after the power supply from the battery to motor is stopped by switching OFF the power relays. The controller then determines whether the capacitor voltage has dropped after each capacitor is discharged. Based on the determination result of the voltage drop in each of the capacitors, the controller can determine whether the power supply relays or the capacitors are malfunctioning.