High voltage dual active bridge with series connected high voltage silicon carbide (SiC) devices

Abstract

Using 6.5 kV Silicon (Si) IGBTs, high voltage high power DC to DC converters are realized either by multi-level converters or series connected devices based two level converters or modular multi-level converter using series connected devices two level converter as building blocks. The introduction of high voltage SiC devices (10 kV to 20 kV) reduces the component count significantly while improving the efficiency and power density of the converter. To explore further, this paper investigates the state of the art high voltage (>10 kV) SiC devices for high voltage dual active bridge (DAB) with series connected devices for high power applications. Experimental results for static and dynamic voltage balancing of 15 kV, 20 A SiC IGBT devices are given to validate the feasibility of series connection and also the experimental characterization of 10kV SiC MOSFET and 15 kV SiC IGBT with RC snubber are reported. By using energy loss data from the experimental characterization, HV side switching loss of a 1 MVA 16 kV/2 kV DAB topology has been evaluated for two independent cases with 10 kV, 10 A SiC MOSFET and 15 kV, 20 A SiC IGBT on the HV side of the converter, while using 1.7 kV Si IGBTs on LV side of the converter.