Zero voltage switched chopper with SiC-MOSFETs

This paper describes a study applying SiC-MOSFETs to soft switching topology with ZVS (zero voltage switching) and evaluating performance of new dc-dc converter when compared with conventional one with silicon IGBTs. Soft switching topology is SAZZ (snubber assisted zero voltage zero current transition) proposed for high frequency, high efficiency and high power boost chopper. In optimization of SAZZ circuit design as the same output power chopper, capacitance of snubber capacitor could be reduced according to higher and higher rating voltage and switching speed of SiC-MOSFETs. In this paper it is shown that the improvement of total efficiency is possible with reduction of auxiliary circuit loss for soft switching using SiC-MOSFETs. Experimental results corresponding to 100 kHz, 8 kW boost chopper are presented with 1200 V, 33A SiC-MOSFETs. Total efficiency is improved from 97.8 % to 98.5 %.