Modeling and characterization of a 1 KW CCM PFC converter for conducted EMI prediction

The wide application of the power factor correction (PFC) techniques in the distributed power system (DPS) and the stringent international standards make it necessary to understand and predict the conducted electromagnetic interference (EMI) of the PFC circuit. Time domain simulation plus fast Fourier transform (FFT) is a viable method. However, the simulation circuit has to be carefully modeled, and must cover high frequency characteristics up to 30 MHz. For this purpose, multiple modeling and characterization techniques in the medium and high frequencies are developed, which finally lead to a good simulation circuit in Saber for a 1 KW continuous-conduction-mode (CCM) PFC converter. The conducted EMI of the PFC converter has been successfully predicted up to 30 MHz in terms of both differential-mode (DM) and common-mode (CM) noise, which substantiates the afore-mentioned modeling and characterization techniques. To explain the conducted EMI behavior of the CCM PFC in a systematic way, the DM and CM loop models of PFC EMI are proposed for describing the noise generation and propagation mechanisms. The effects of the PFC inductor and the parasitic capacitances at the MOSFET drain node are investigated to verify the validity of the DM and CM loop models.