EMI filter for boost PFC converters based onhighfrequency model of commonmode chokes
                                            CHEN Hao, HU Yaowei, WANG Lei, CHEN Dongdong, CHEN Guozhu
                                            (College of Electrical Engineering, Zhejiang University, Hangzhou 310027, China)

Abstract: Aiming at the problem of conducted electromagnetic interference in Boost PFC converters, through the analysis of its commonmode and differentialmode interference conduction paths in Boost PFC converters with or without the balanced capacitor, the causes and suppression methods of mixedmode conducted electromagnetic interference in Boost PFC converters were studied. Considering the frequency characteristics of the core material and winding parasitic capacitors, the nonideal factors of commonmode chokes and the limitations of the existing highfrequency model were summarized. An improved Foster network series model was established and an EMI filter design scheme based on optimization of highfrequency impedance characteristics. Experiments were carried out using a prototype of 1.25 kW Boost PFC converter. The results indicate that after the designed EMI filter was added to the circuit, the device under test can pass the conducted interference test successfully.

Key words: conducted electromagnetic interference; balanced capacitor; high frequency model; EMI filter