A study on the diagnostic and fail-safe of the PMSM

Abstract

A motor fault must be detected immediately and fault tolerant control is used to significantly reduce the effects from the fault. In this paper, four types of fault are defined and the varied fault tolerant control methods are discussed. Herein, faults are classified in four types: encoder, DC link voltage, DC link current, and phase current. In the case of encoder faults, the hall signal can be used to estimate the rotor position. Fault tolerant control using the defined voltage is performed for a DC link voltage fault. When the DC link current provides a malicious value, the fault tolerant control uses the DC link current, converted from the phase current, and the motor performs in limited mode. Because the phase current has the same RMS and frequency, and a phase difference in a certain place, the difference in the current signal is used to detect the fault. When phase current fault happens, fault tolerant control is performed using the other phase current signals. As a result of this work, the defined fault types could be immediately detected and the fault tolerant control performed without any problems.