A criterion function for broken bar fault diagnosis in induction motor under load variation using wavelet transform

Abstract

In this paper a novel criterion function is introduced to diagnose the breakage in rotor bars, which uses wavelet transform (WT) to process the stator current signal in faulty induction motors. This criterion function facilitates the diagnosis of fault in induction motors under load variation, precisely. The proposed function is based on wavelet coefficients of stator current in a specific frequency band. Meanwhile, in this paper broken rotor bar in induction motor is detected using spectrum analysis of stator current. It is also shown that increasing the load makes an increase in harmonic components amplitude of a faulty induction motor. A Time stepping finite element (TSFE) method is used for modeling broken rotor bar faults in induction motors. In this modeling, the effects of the spatial distribution of the stator winding, non uniform air-gap permeance, geometrical and physical characteristics of different parts of the motor, and finally non-linearity of the core materials are taken into account. The proposed algorithm is applied to the stator current of a healthy and faulty induction motor. The simulation results are obtained and their accuracy is verified by experimental results.