Design of Active EMI Filter for CM EMI Suppression with Cascaded Structure

In power electronic equipment, electromagnetic compatibility (EMC) is an important issue to ensure the reliable operation of the system. The performance of the electromagnetic interference (EMI) filters is critical to the EMC characteristics of the equipment. For the passive EMI filter which is used as the primary method for EMI suppression, its performance can be improved by cascading other passive EMI filters and a similar method can be used in the active EMI filter (AEF) which is composed of active components. In this paper, a current-sensing current-compensating AEF with cascaded structure for common mode (CM) EMI suppression is proposed. The CM EMI suppression effect of the cascaded AEF is verified by experiment, and it can suppress CM EMI better than the single stage AEF.