Evaluation of 1.2 kV SiC MOSFETs in Modular Multilevel Cascaded H-Bridge Three-Phase Inverter for Medium Voltage Grid Applications
This paper describes a study evaluating 1.2 kV SiC MOSFETs in modular multilevel cascaded H-bridge (CHB) threephase inverter for medium voltage ac grid applications. The main purpose of this topology is to remove the need of a bulk 60 Hz transformer that is normally used to step up the output signal of a voltage source inverter to the medium voltage level. Using SiC devices (1.2 kV ~ 6.5 kV SiC MOSFETs), with their high breakdown voltage, enables the system to meet and withstand the medium voltage stress, with a minimized number of cascaded modules. The SiC-based power electronics, when used in the presented topology, they significantly reduce the complexity usually faced when Si devices are used to meet the medium voltage level and the power scalability. The simulation and preliminary experimental results, on a low-voltage prototype, verifies the ninelevel CHB topology that is presented in this paper.