Fault Diagnosis of Inter-turn Short Circuit Faults in Dual Three-Phase PMSM Drives

Abstract

The high current density of the multiphase PMSM drives makes it more prone to inter-turn short circuit fault. If the fault can not be detected in time, it may cause secondary fault or even damage the motor. Therefore, this study proposes an online fault diagnosis strategy for inter-turn short circuit fault of dual three-phase permanent magnet synchronous motor (PMSM) drives. The proposed diagnosis strategy integrates the state observation method and the high-frequency injection method, and the iterative method is used to reduce the amount of calculation in online detection. In the state observation method, an extended state observer is introduced to observe the back EMF of PMSM, and the negative-sequence component of back EMF in the static coordinate system is extracted to get the fault index to measure the severity of the fault. For the high-frequency injection method, the change of motor impedance in high frequency can be used to locate the faulty phase and assist in identifying the severity of inter-turn short circuit fault. The two detection methods can be integrated into the DSP controller, and only the phase current, the terminal voltage and the more speed are needed as inputs without additional sensors. The simulation is carried out on MATLAB / Simulink platform. The results show that the diagnosis method is effective, and the fault parameters obtained by the diagnosis can also provide parameters for the fault-tolerant control of the motor.