3-Phase Inverter Current Sensor Fault Diagnosis by Cycle-Average Vector
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Solution Overview
Problem
Existing systems for electric steering systems, which rely on phase current sensors for 3-phase inverters, fail to accurately diagnose sensor failures, leading to potential safety issues due to incorrect current compensation and resulting noise and vibration.
Innovation Solution
A diagnostic apparatus and method that includes phase current sensors, a controller to process and compare the magnitude and angle of detected currents with reference values, and additional components like a space vector pulse-width modulator and DQ converter to determine sensor failure by analyzing the average current over a cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phase current sensor failure is not diagnosed, then the system operates continuously, but excessive current is supplied to specific phases causing safety issues and motor damage
Solution Approach 1:
The system performs preliminary diagnostic actions by continuously monitoring phase current sensors and detecting failures before they cause excessive current supply. The controller checks sensor output values against expected ranges and identifies failures in advance, preventing harmful effects before they occur.
Solution Approach 2:
The system implements feedback by continuously monitoring phase current sensor outputs and comparing them against expected values. When deviations are detected, the system provides feedback signals to indicate sensor failure, enabling real-time detection and prevention of excessive current supply to motor phases.
2Productivity
If current sensor errors are compensated without diagnosis, then steering operation continues, but incorrect current compensation causes noise and vibration
Solution Approach 1:
The system performs preliminary diagnosis of current sensor failures before attempting compensation. By detecting sensor failures in advance through monitoring output values against expected ranges, the system prevents incorrect compensation that would generate noise and vibration, while still maintaining operational continuity.
Solution Approach 2:
The system converts the potentially harmful effect of undetected sensor failures into a beneficial diagnostic opportunity. By monitoring sensor outputs and identifying deviations from expected values, the system transforms what could be a source of noise and vibration into a detectable signal that triggers failure diagnosis and prevents harmful compensation.
3Reliability
If phase current sensor failure is detected, then safety is improved, but the diagnostic method complexity increases
Solution Approach 1:
The system monitors changes in sensor output parameters (current values) against expected ranges and detects failures when parameters deviate from normal operating conditions. This parameter-based monitoring approach enables accurate failure detection through straightforward comparisons rather than complex diagnostic algorithms.
Solution Approach 2:
The system replaces complex mechanical diagnostic procedures with electronic monitoring and software-based detection. By using the controller to monitor sensor outputs and compare against expected values, the system achieves accurate failure detection through electronic means rather than requiring complex mechanical diagnostic equipment or procedures.
Data Source
AI summary
The present disclosure relates to an apparatus and method for diagnosing a failure, which may include a motor, an inverter for driving the motor, a phase current sensor for respectively detecting a phase current supplied to the motor from the inverter, and a controller for converting the phase current detected by the phase current sensor into a current, obtaining an average value of the current in one cycle and comparing the magnitude and angle of the average value with a reference value to determine a failure of the phase current sensor.