Comparison of SST Topologies Suitable for Energy Applications

Abstract

This paper presents an assessment of Solid State Transformer (SST) topologies from the usability in energy applications point of view. SSTs are nowadays at the center of researchers’ attention mainly due to reducing size and weight of traction transformers in railway vehicles. Our contribution aims to use the SST as a cornerstone of an Energy Router that should replace a typical distribution substation with a classical transformer. After a general overview of SST topologies classification an overview of design guidelines for key SST components (ferrite cores for medium frequency (MF) transformers, semiconductors and high voltage capacitors) is presented for two topologies that seem to be promising for energy applications: classical three-stage SST and two-stage SST with a low voltage DC link and galvanic insulation in the first stage. These two topologies are then compared from an economical point of view based on acquisition cost of key components in order to evaluate whether the technology has matured to be used commercially.