Analysis and accurate modeling of a flyback converter on conducted EMI

In this paper an accurate EMI model of a 5W flyback converter based on discrete devices modeling is presented. To improve the accuracy of EMI model, passive devices, active devices, power IC and the parameters of PCB are all taken into consideration. The simulation results show that, errors of main system-level parameters can be controlled in 5% and errors at the EMI peak values can be controlled in ± 5dB. Based on the proposed model, the existence of NIDM noise is verified and the impacts of parasitic parameters on PCB in this flyback converter are analyzed. The model-based analysis of EMI agrees well with the theory and measurement.