Investigating Current and Radial Shaft Displacement of Induction Motor Driven by Pulse-Width Modulation Inverter for Bearing Fault Detection

Bearing faults account for a large majority of the faults in three-phase induction motors. Many researches have been conducted to develop a diagnosis technique for bearing faults using the motor current in an induction motor. However, the characteristics of the motor stator current and radial shaft displacement have not yet been clarified when there is a faulty bearing in an induction motor driven by a PWM inverter. The purpose of this paper is to investigate the relationship between the power spectral density of the rotational frequency band of the stator current and the radial shaft displacement of the induction motor driven by a PWM inverter. Experiments were performed with normal and abnormal motors. Then, the characteristics of the power spectral density of the rotational frequency band of the stator current are discussed based on the experimental results of the radial shaft displacement.