Current signature identification and analysis for demagnetization fault diagnosis of permanent magnet synchronous motors

Abstract

Monitoring the safety and reliability of the motor has become a very important research field as a motor has been used as a main power source for electric vehicles. In this study, we propose a physics-based method for identifying the fault indicator for the demagnetization of permanent magnet synchronous motors with no fractional harmonics during its operation. The concept of deterministic current was introduced, which is theoretically calculated based on motor parameters with the consideration for control scheme. The fault-related current signatures were found by analyzing the deterministic current through signal processing technique. Unlike the previous studies it was found that the 8th harmonic component in stator current waveform rather than fractional harmonics is good indication for the demagnetization of PMSM. Simulation and experiment were also conducted using motors with different fault severity to verify the effectiveness and accuracy of the proposed method. In addition, simulation and experimental results show that the proposed scheme is valid regardless of the operating conditions of the motor.