Reduction of common mode currents in PWM inverter motor drives

Abstract

Modern pulsewidth modulation (PWM) inverter motor drives are affected by dangerous common-mode currents due to the high rate of variation of the modulated voltage. An inexpensive alternative to low-pass filters, which are normally used to limit common-mode currents, consists in reducing such currents by using suitable modulation strategies. In this paper, a new approach for designing PWM strategies is presented, which is able to reduce common-mode currents by limiting the amount of variations of the common-mode voltage. The main characteristics of the proposed approach are experimentally evaluated on a standard PWM induction motor drive.