Investigation of Broken Rotor Bar Fault in Field Oriented Controlled Induction Motor Using Discrete Wavelent Transform

Fault diagnosis of Induction motor has been successfully done using motor current signature analysis. However, this technique is not effective with non-stationary signal associated with varying-load operation. With current development in motor drives, precise control techniques like field oriented control tend to mask the effect of fault, making diagnosis more difficult. This has prompted the application of Wavelet transform, a multi-resolution signal processing technique that can capture transient features. This paper investigates the effect of Broken Rotor Bar (BRB) fault in motor stator current using discrete wavelet transform to validate the robustness of wavelet diagnostic procedure over control regulator parameters and motor load. To achieve this, BRB fault is modelled in MATLAB/Simulink and the sampled signal processed using MATLAB commands. The results show that detail coefficient plot that correspond to low frequency range between 39Hz and 156Hz provide relevant information about fault presence where the operating frequency is 50Hz. The amplitude variation with severe conditions further makes discrete wavelet transform an effective fault scaling tool for field oriented controlled induction motor.