Research and design of a common mode hybrid EMI filter for switch-mode power supply

After the study of electromagnetic interference (EMI) mechanisms in switching mode power system (SMPS) and the soft switch, this paper proposes a novel hybrid filter (HEF) to suppress commend mode EMI in SMPS. This paper reviews the limits of pure passive and active EMI filter and discusses the advantages of the hybrid EMI filter (HEF). By studying the insertion loss, impedance compatibilities, and reliability of the hybrid EMI filter, a new HFF topology is proposed in this paper. And an example of HEF for flyback converter is designed. And the topology has been simulated in Saber. The simulation result verifies its advantages in better attenuation, lower cost, and higher efficiency.