Comparison of Hybrid Si/SiC and SiC Two-Level and Three-Level Converters for Low-Voltage Low-Power Applications

Abstract:
This study compares SiC two-level converters with hybrid Si/SiC and full-SiC three-level converter topologies for low-voltage and low-power applications in terms of electrical performance. Analytical loss models are derived for each topology and the loss models are iteratively solved with a thermal equivalent circuit. The results show that full-SiC three-level converters are slightly superior to hybrid Si/SiC equivalents in terms of output power capability and converter efficiency. Moreover, three-level converters do not offer major electrical performance improvements compared to two-level converters if SiC is used. The switching frequencies at which three-level converters are better than two-level converters are shifted to relatively high frequencies for SiC-MOSFETs compared to Si-IGBTs. For 400 V AC systems, two-level SiC converters are the most attractive option. For 690 V AC systems, three-level topologies can not be dismissed because 2300 V SiC chips are not available in the market yet.