Impact of SiC/Si Technology on the conducted EMI generated by a Buck converter

This paper presents a comparative study of conducted common mode(CM) and differential mode(DM) EMIs generated by a DC-DC BUCK converter based on silicon (Si) or Silicon Carbide (SiC) Diodes and/or MOSFETs. Using Si technology as a reference, the prediction of EMI waveforms is carried out with simulation in both time and frequency domains using LTspice software. The paper shows the great influence of the use of SiC Diodes on the conducted EMIs in the frequency range [10MHz -100MHz]. The obtained results show that the switching cell equipped with the SiC MOSFET has a faster switching and a faster current response (High di/dt and dv/dt) generating an increase in CM and DM disturbance. Using SiC technology for both the MOSFET and Diode shows a reduction of conducted EMI for frequencies greater than 20MHz. The association of Si MOSFET and Sic Diode reduces conducted EMIs generated by the converter.