Diagnosis of open-phase fault of five-phase permanent magnet synchronous motor by harmonic current analysis

Abstract

A new fault diagnosis strategy is proposed for the single-phase (two-phase) open-circuit faults of the five-phase PMSM (FP-PMSM). Firstly, the output characteristics of the terminal voltage before and after the open-circuit fault are analyzed, and the expressions of the fundamental current in the α-β subspace under 15 fault states and normal states are obtained. The trajectory of the fundamental current in the α-β subspace is circular in the normal state and elliptic in the fault state. Therefore, the open-circuit fault determination is based on the distance from the current trajectory to the origin. Secondly, according to the output characteristics of the terminal voltage under different fault states, the trajectory distribution characteristics of the third harmonic current in the d-q subspace under 15 open-circuit fault states are obtained. By comparison, the trajectory distribution characteristics of different open-circuit faults are very different, which can be used as a basis for fault location. Finally, an experimental platform built with DSP as the core is used to verify the proposed fault diagnosis strategy. Experimental results show that the fault diagnosis strategy quickly determines and locates faults in steady-state and dynamic conditions.