Analyzing common-mode chokes for induction motor drives

This paper first analyzes the required characteristics of common-mode (CM) chokes for induction motor (IM) drive applications. It then presents an approach for specifying CM chokes in order to achieve specified CM-current reductions. To this end, a high-frequency IM model based on the IM zero-sequence impedance is suggested. The CM choke specification should be based on its particular application due to the unique characteristics of the CM currents. The ideas are verified by laboratory experiments.