Application of EWT for Analysing Stator Inter-Turn Fault in SPMSM using Finite Element Method

Abstract

Stator winding inter-turn short circuit (ITSC) accounts for 21 % of faults in Permanent Magnet Synchronous Motors (PMSM). One of the biggest challenges in the area of inter-turn fault is to detect the fault having less than 10% of total turns in a phase. In this paper, an attempt is made to analyse stator inter-turn fault in Surface Mounted Permanent Magnet Synchronous Motor (SPMSM) using Finite Element Method (FEM). A 0.55 kW SPMSM model is obtained from ANSYS Maxwell finite element tool and it is linked to ANSYS Simplorer by transient - transient link to supply power and apply load to the motor. Three phase voltage source inverter with Space Vector Pulse Width Modulation (SVPWM) control technique is created in MATLAB Simulink and coupled with Simplorer to control the machine. Analysis is carried out for different inter-turn fault severities such as 15T (7.2%), 30T (14.4%) and 45T (21.6%) respectively. Various machine parameters such as phase current, torque, speed, flux distribution over the machine and radial air gap flux density are analysed and compared with faulty machines. It has been observed that flux density distribution is less in the stator teeth and core region of faulty coil and the rms value of winding current and radial air gap flux density increases proportionally with severity of ITSC fault. Empirical Wavelet Transform (EWT) is applied to analyse the stator current of SPMSM for various inter-turn severities. It is observed that peak magnitude of the EWT decomposed components increases when there is increase in severity of fault.