Modelling and simulation of stator and rotor fault conditions in induction machines for testing fault diagnostic techniques

On-line diagnostics of induction machine faults such as broken rotor bars and shorted stator windings can be accomplished by analysing the anomalies of machine stator current. Defective rotor bars result in twice slip frequency sidebands around the fundamental frequency in the stator current, while stator winding short circuits cause changes in stator current amplitude and the occurrence of negative sequence current. This paper presents an induction machine model based on the Coupled Circuit Approach to simulate both the rotor and stator faults in an induction machine and to test fault diagnostic techniques. This model is realized in Matlab/Simulink and its construction in Simulink is explained with sufficient details. Simulation results of both the rotor and stator fault conditions are presented. A novel high-resolution spectral analysis approach and a technique based on Discrete Fourier Transform (DFT) for the detection of broken rotor bars are tested using the simulated data. The results confirm that the high-resolution method overcomes drawbacks of DFT such as the requirement for long data windows.