Design considerations of 6.5kV enabled three-level and 10kV enabled two-level medium voltage SST

The advent of medium voltage silicon carbide (SiC) power semiconductor devices (6.5kV and 10 kV) has opened up the possibilities of looking into different converter topologies for the MV grid interfaced applications. A medium voltage mobile utility support equipment-based three-phase solid-state transformer (MUSE-SST) system is one such application aimed to interconnect a three-phase 4160 V/60 Hz grid to a three-phase 480 V/60 Hz grid to provide a shore-to-ship power interface for naval vessels. The system can be realized by both 10 kV SiC MOSFET and 6.5kV SiC MOSFET employing a two-level and three-level architecture respectively. The aim of this paper is to understand the thermal challenges and provides detailed design considerations of the two MV device-based architectures for a system scale-up to 500kVA rating. Device characteristics for both 6.5kV and 10kV SiC MOSFETs have been evaluated from experimental results. Based on these experimental data, the thermal performance of these devices enabled converter architecture is compared using elctro-thermal simulation-based loss comparison.