Black-Box Modeling of EMI Filters for Frequency and Time-Domain Simulations

A procedure for the derivation of a black-box model of electromagnetic interference (EMI) filters is proposed and discussed. The modeling approach is assessed by resorting to a real EMI filter. The equivalent circuit of the filter is directly obtained from a rational approximation of the scattering-parameter matrix measured at the filter ports. Therefore, the modeling procedure does not require any information on the internal structure of the filter (e.g., components, electrical/magnetic properties of the involved materials, connections leads, etc.). The circuit model is compatible with SPICE solvers and can be used for the prediction of conducted emissions in both the frequency and time domain. Specifically, the proposed modeling approach allows time-domain simulation and performance analysis of EMI filters in combination with power-electronic equipment (i.e., nonlinear, time-variant circuits).