A Transistor‐Based Common‐Mode Active EMI Filter Design for DC–DC Converter

With the advancement of power electronic technology, various power converters are now employed for electric energy conversion. However, the fast and continuous switching of power devices in power converters inevitably generates serious electromagnetic interference (EMI), potentially threatening the reliability of the system. Compared to the most widely‐applied bulky passive EMI filter, active EMI filters (AEFs) composed of active components offer smaller size and higher power density. Instead of using the expensive operational amplifiers, a fully transistor‐based AEF for common‐mode (CM) EMI suppression, featuring a low‐cost design, is proposed in this paper. The proposed AEF presents the advantages of low cost and can realize high compactness, flexible, and easy‐controllable design. The working principle of the proposed AEF is demonstrated in detail, and the insertion loss provided by the AEF is predicted by calculation and simulation. Experimental test results demonstrate a strong agreement with the theoretical calculation results, confirming the effectiveness of the proposed AEF.