Evaluation of rise in common mode voltage with variation in switching frequency for two level inverter fed induction motor drive

Common mode voltage (CMV) and switching frequency of an inverter fed induction motor drive are dependent quantities. Increase in common mode voltage (CMV) with increase in switching frequency for induction motor drive is studied in this paper. Conventional sinusoidal pulse width modulation technique is used to drive an inverter fed induction motor. It is demonstrated that the peak value of CMV increases by an amount of 5% with respect to DC bus voltage for increase in switching frequency from 1 kHz to 16 kHz. This may cause severe damage to motor drive when inverter is operated at higher switching frequencies in order to reduce size and overall cost of the drive. It is suggested to take preventive measures towards reduction or mitigation of CMV while operating wide band-gap semiconductor devices based highly efficient and compact motor drives. As these switches are operated at higher switching frequencies, unacceptable rise in CMV should be minimized.