LPV Phase Current Observer for Motor Sensor Failure Detection
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Solution Overview
Problem
Conventional current sensor failure detection algorithms in PMSM motor control systems are inadequate for comprehensive failure detection, and existing observers fail to reliably estimate phase current signals, leading to instability and unreliable operation.
Innovation Solution
A linear parameter-varying (LPV) observer that estimates phase current values using reference control loop voltages, angular position, and velocity signals, combined with a failure detector to replace sensed current values with estimated values in case of sensor failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional current sensor failure detection algorithms are used, then the system can detect specific types of sensor faults, but the detection is not comprehensive and fails to detect all sensor failures
Solution Approach 1:
The LPV observer is designed to perform multiple functions: it estimates phase current signals for normal control operations and simultaneously detects various types of current sensor failures including offset errors, gain errors, and complete sensor failures. This multi-functional approach enables comprehensive failure detection across different fault modes without requiring separate detection algorithms for each fault type.
Solution Approach 2:
The system continuously compares the estimated phase current signals from the LPV observer with the actual sensed current signals from the current sensor. This feedback mechanism enables real-time detection of discrepancies indicating sensor failures. The observer gain is adjusted based on feedback from the comparison result, allowing dynamic adaptation to different operating conditions and fault types.
2Measurement precision
If conventional observers such as Luenberger observer or linear observer are used, then the system can estimate current signals, but the estimation performance is inadequate and cannot reliably detect sensor failures
Solution Approach 1:
The LPV observer employs dynamic observer gains that are adjusted in real-time based on the operating conditions of the PMSM drive system. The observer gain is modified according to the instantaneous operating point, allowing the observer to maintain high estimation accuracy across varying speeds and loads. This dynamic adaptation enables reliable failure detection that static conventional observers cannot achieve.
Solution Approach 2:
The system changes the observer parameters (gains) based on the operating conditions to optimize estimation performance. By adapting the observer parameters to match the current operating state, the LPV observer achieves superior current signal estimation accuracy and reliability compared to fixed-parameter conventional observers, enabling dependable sensor failure detection.
3Productivity
If the system operates with closed-loop current control, then the control performance is improved, but sensor failures become undetectable in the output feedback system
Solution Approach 1:
The LPV observer acts as an intermediary that generates estimated current signals independent of the current sensor feedback path. By creating a parallel estimation channel that does not rely on the sensed current signals, the system can detect sensor failures even when operating in closed-loop current control mode. The observer provides an alternative current signal path that reveals sensor faults through comparison.
Data Source
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AI summary
A linear parameter-varying (LPV) observer for an electric motor controller. The controller includes a control loop with a current sensor that senses phase current signals driving an electric motor and that provides sensed current values used in the control loop. The observer includes an input interface and a processor. The input interface provides a sensed angular speed value, a sensed angular position value, physical parameters of the electric motor, and a pair of control loop control voltages used in the control loop. The processor calculates estimated current values indicative of the sensed current values using the angular speed value, the angular position value, the pair of control voltages, and the electric motor physical parameters. A failure detector may compare the sensed current values with the estimated current values to detect a failure, and substitute the estimated current signals for the sensed current signals when a failure is detected.