Continuous switching operation of 15 kV FREEDM super-cascode

High voltage and wide bandgap (WBG) semiconductor devices like the 15 kV SiC MOSFET have attracted a lot of attention because of their potential applications in high voltage and high power converters. However, they are not commercially available at present and their high cost might be a hindrance to their widespread adoption in future. To address the commercial unavailability and the high cost issues of the 15 kV SiC MOSFET, the 15 kV FREEDM Super-Cascode, which is based on 1.2 kV SiC MOSFET and JFETs series connection, is designed and developed. In this paper, the high switching frequency operation of the newly developed 15 kV, 40 A FREEDM Super-Cascode is tested and reported for the first time. A 7.2 kV ac rms input, 400 V dc output, 40 kW converter is designed using the 15 kV FREEDM Super-Cascode, whose switching frequency varies from 15 to 64 kHz.