Three-phase inverter differential mode EMI modeling and prediction in frequency domain

This paper describes a frequency domain approach to the prediction of differential mode (DM) conducted electromagnetic interference (EMI) for a three-phase inverter at the early design stage. The approach is able to calculate the DM conducted EMI with more accurate noise source and parasitic path identification. The DM noise sources are identified as three device switching current and their frequency domain expressions are derived according to inverter operating principle. The parasitic components are identified using FEM analysis. The calculated DM EMI result is compared with experimental data and it can predict the high frequency resonant peak precisely. It is indicated that the frequency domain analysis with accurate noise source and parasitic modeling is an effective tool for DM EMI prediction for three-phase inverter circuit.