Evaluation of Common Mode Disturbance Mitigation Devices in AC Motor Drives through HF Modelling

In this paper a method for verifying the performance of both passive filters and active compensation devices for common mode disturbance mitigation in PWM induction motor drive is presented. The method is based on the use of a lumped parameters HF circuit model of the whole drive simple to be implemented and studied through a standard circuit simulation software such as PSpice. Two solutions to reduce the common mode current flowing through the earth connection of the motor have been set up, these solutions are based respectively on a passive common mode choke and on an active common mode canceller. The comparison between simulated data and experimental tests allows to assess the suitability of the proposed model to accurately predict the impact of the different mitigation devices on common mode HF currents propagating within the drive