Study on Prediction Models of EMI Filter with Near-field Coupling Effect

With the electromagnetic compatibility (EMC) standard becoming more stringent, the EMI filter plays an important role for reducing the electromagnetic interference (EMI). Therefore, it needs an accurate model of EMI filter to predict its attenuation characteristic for more easily improving performance in design step. In this paper, we proposed respectively differential-mode and common-mode models for EMI filter. We used the method of impedance curve fitting to extract the parasitic parameters of the equivalent circuits, and used the electromagnetic finite element simulation to analyze and obtain the near-field coupling coefficients in the EMI filter. Finally, we used the comparison between simulated and measured S21 parameters to verify the accuracy of modeling methods for EMI filter.