Design of a differential mode active EMI filter based on conducted emission analysis used in DC/DC converter

This paper presents a novel active EMI filter (AEF) topology specially used to reduce the differential mode (DM) electromagnetic interference (EMI) noise in a full bridge DC/DC converter. The AEF was mainly reported to reduce the common mode (CM) EMI noise in the past, and the proposed circuit extends the application of the AEF to eliminate the DM EMI. In this work, differential mode emission conduct mechanism and full bridge DC/DC converter modeling are combined to develop a practical voltage feedback DM AEF, which is aimed to achieve a large insertion loss. Experimental results to demonstrate the performance and effectiveness of the proposed AEF are also presented.