Startup Scheme for the Active Front End Converter in a Medium Voltage Mobile Utility Support Equipment based Solid State Transformer (MUSE-SST)

摘要

Rapid growth in the field of power semiconductor devices has enabled the development and production of medium voltage wide bandgap semiconductor devices such as 15 kV SiC IGBTs and 10 kV SiC MOSFETs. These devices have opened up opportunities for using simple converter topologies in various medium voltage applications like solid-state transformers, high-speed motor drive applications, shore-to-ship converters, etc. A medium voltage Mobile Utility Support Equipment based Solid-State Transformer (MUSE-SST) enabled by Gen3 10 kV SiC MOSFETs is developed at FREEDM Systems Center to integrate a 4.16 kV grid to a 480 V grid or a load. While these SiC devices offer a multitude of advantages in terms of lower losses and superior switching speeds as compared to their silicon counterparts, the inrush handling capacity is limited. This can prove detrimental to the power semiconductor devices and consequently the entire system if adequate measures are not taken during the startup of the solid-state transformer. This is especially critical in the case of medium voltage grid-connections due to a comparatively higher voltage level. In this paper, various startup schemes are explored for connecting the medium voltage grid to the solid-state transformer as well as different schemes for minimizing the inrush current during turn-on of the active front end converter are also shown. Simulation and initial experimental results and are provided to validate the startup schemes.