500kVA Hybrid Solid State Transformer (HSST): Design and Implementation of the SST

This paper presents the design and implementation of a solid-state transformer (SST) that forms a part of a larger Hybrid Solid State Transformer (HSST). The HSST comprises of a high-power line frequency transformer (LFT) and a medium voltage SiC SST. The SST is based on a soft-switched dual-active bridge topology. Recently developed 7.2kV/60A SiC Austin SuperMOS devices are used as the medium voltage switches. The predicted SST efficiency at 500VRMS and 125A is 98.01 %, and the net HSST efficiency is estimated at 98.43 % at 500kVA. The MV SST has been tested at power of 10kW and results show a high efficiency of 97%.