Analysis of Inverter-Fed Squirrel-Cage Induction Motor During Eccentric Rotor Motion Using FEM

Asymmetric electromagnetic force caused by the frictional worn bearing, rotor misalignment, and unbalanced rotor, etc., leads to an asymmetrical operation, vibration, and electromagnetic noise. The need for the detection of these rotor eccentricities has lead to the development of monitoring methods by increasing sensitivity and noise immunity. This paper proposes a diagnosis method for an induction motor driven by a PWM-controlled inverter considering the harmonics in a transient magnetic phenomenon. The effects of asymmetrical whirling motion are studied using the current, vibration spectrum, and back EMF of a search coil. The analysis results of rotor eccentricity could be obtained by comparing the characteristics of motors that have normal and irregular air gaps and verified reliability. Simulation and experimental results can be useful for online fault detection monitoring systems for induction motors.