Detection of rotor broken bar and eccentricity faults in induction motors via second order sliding mode observer

This paper provides a novel approach for detecting certain abnormal operating conditions in squirrel cage induction motors (SCIMs). A mathematical model of the faulty operating mode is derived with the rotor broken bars and the rotor eccentricity being the faults of interest. To detect the fault occurrence, an appropriate FDI observer, based on second order sliding modes, is presented and analyzed by Lyapunov methods. The ability of the suggested FDI observer to produce suitable residual signals which allow a reliable threshold-based fault detection is shown. Once the fault is detected, dedicated FFT analysis of the residuals allows the classification of the fault. The proposed scheme has been verified by real implementation tests using measurements taken from certain commercial three-phase SCIMs intentionally damaged in order to reproduce the fault scenarios of concern. Experimental results confirm the reliability of the suggested framework.