Bearing current profiles in a 3-phase VSI fed induction motor drive using a simplified measurement approach

This paper presents a new simplified method of measuring the bearing current in the induction motor driven from a voltage source inverter (VSI). This proposed method significantly reduces the modifications required to be made from inside the motor for making necessary measurements, making it an inexpensive proposition. This paper introduces two types of bearing current profiles and also makes a comparison of bearing current obtained with reduced common mode voltage(CMV) pulse width modulation(PWM) and coventional PWM methods. Suitable experiments are carried out on an FPGA controlled VSI driving a 3-phase induction motor drive suggests that reduced CMV-PWM is said to result in no electric discharge machining (EDM) current compared to the other PWMs and this is justified by using power spectral density analysis presented in this paper. © 2012 IEEE.