Mechanical load fault detection in induction motors by stator current time-frequency analysis

This paper examines the detection of mechanical faults in induction motors by stator current analysis. Mechanical faults lead generally to periodic load torque oscillations. The influence of the torque oscillations on the induction motor stator current is studied. The mechanical fault results in a sinusoidal phase modulations of the stator current. Based on these assumptions, several signal processing methods suitable for stator current signature analysis are discussed: classical spectral analysis, instantaneous frequency estimation and time-frequency analysis using the Wigner distribution. Experimental and simulation results validate the theoretical approach