Differential mode EMC input filter design for three-phase AC-DC-AC sparse matrix PWM converters

The design of a differential-mode EMC input filter for a three-phase AC-DC-AC very sparse matrix converter intended for electrical machine drive applications is discussed in this paper. A review of the steps to be performed in the course of the filter design is presented and a detailed mathematical model of the EMI test receiver for quasipeak measurement of conducted emissions in the frequency range of 0.15...30 MHz is established. Furthermore, formulas for the estimation of the quasipeak detector output based on the LISN output voltage spectrum are provided. As experimentally verified by using a novel three-phase CM/DM separator this procedure allows an accurate prediction of the converter differential mode conducted emission levels and therefore could be employed in the design process for ensuring compliance to relevant EMC standards.