Analytical evaluation of modulation effect on three-phase inverter differential mode noise prediction

This paper presents the modulation effects on the differential mode (DM) conducted electromagnetic interference (EMI) for a three-phase inverter. The evaluation is to adopt a newly developed frequency-domain DM EMI prediction method with accurate noise source and parasitic path identification. Three different modulation schemes are studied and different DM noise sources expressions in frequency domain are derived. The parasitic components are identified using finite element analysis method (FEM). The calculated DM EMI results are compared with experimental data. It is indicated that the modulation schemes have significant impacts on EMI performance not only in switching frequency and its associated harmonics, but also in higher frequency regions.