High-Voltage Relay Diagnostic System for EV Safety
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Solution Overview
Problem
High-voltage relays in electric or hybrid vehicles can fail, leading to safety hazards due to constant exposure to high voltage even when the vehicle is not in use, necessitating a method to diagnose relay failures effectively.
Innovation Solution
A high-voltage relay system that includes a first and second contact part, a relay between them, a first resistor, and a controller that determines relay failure based on ON/OFF control signals and voltage measurements between the resistor's ends, allowing for the application of constant voltage and signal control to diagnose whether the relay is normal, open, or short-circuited.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a relay is installed in the high-voltage circuit to control power flow, then the ease of operation is improved, but the reliability deteriorates due to potential relay failure causing safety hazards
Solution Approach 1:
The diagnostic system performs preliminary detection of relay status before failure occurs. The controller continuously monitors relay operation state through voltage measurements and control signal analysis, enabling early detection of abnormal conditions such as failure to open or close, allowing preventive maintenance before safety hazards arise.
Solution Approach 2:
The system implements feedback by continuously monitoring the relay's actual state through voltage sensors and comparing it with the expected state based on control signals. When a discrepancy is detected (e.g., relay should be open but voltage indicates closed state), the controller receives feedback and can trigger alarm signals or protective actions to prevent safety accidents.
2Reliability
If a diagnostic system is added to detect relay failures, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The controller serves multiple functions: it controls the relay operation, monitors the relay status through voltage measurements, diagnoses relay failures, and generates alarm signals. By making the controller multi-functional, the system achieves reliable failure detection without adding separate dedicated diagnostic hardware, thus avoiding increased device complexity.
Solution Approach 2:
The relay system performs self-diagnosis by using its own control signals and voltage measurements to detect its own failure state. The controller analyzes the relationship between the control signal it outputs and the actual voltage state it measures, enabling the system to self-monitor and self-diagnose without requiring external diagnostic equipment or complex additional sensors.
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
Enables reliable diagnosis of relay failures, preventing safety accidents by accurately determining the state of the relay through voltage measurements, ensuring safe operation of the vehicle.
Implementation Method 1
a voltage sensor configured to measure a voltage between both ends of the first resistor
Implementation Method 2
a relay disposed between the first contact part and the second contact part and short-circuited or opened
Data Source
AI summary
A high-voltage relay system for a vehicle is provided. The system includes a relay, a first contact part positioned between a battery and a power converter, a voltage application unit, and a second contact part positioned between the voltage application unit and the ground. A first resistor is connected, at a first end thereof, in series to a second end of the second contact part and connected, at a second end thereof, to the ground. A controller operates the relay in response to an ON/OFF control signal to short-circuit or open the contacts at both ends of the first contact part or the contacts at both ends of the second and determines whether the relay fails based on the type of the ON/OFF control signal and the voltage value between both ends of the first resistor.