CHAPTER 9 - Solid state transformers with multilevel inverters

Abstract

The widespread use of distributed generation, integration of renewable energy sources, energy storage systems, and electric vehicles has increased the need for the coupling of different types of sources and loads in a modular power conversion system. The solid-state transformer (SST) has evolved rapidly in this new scenario of utility grid transformation with the aid of power semiconductors and multilevel inverter (MLI) technologies. The improvements seen in SSTs have created a new approach to applications of MLIs. The flexible and reliable architectures are developed with conventional line-frequency and high-frequency transformers for building SSTs, which are assumed to be robust competitors to replace magnetic core transformers. This chapter describes a survey of SST architectures and modular SST research. The main classifications of SSTs, namely input stage, transformation stage, and output stage, are discussed in detail. Device configurations and their design procedures are examined throughout the chapter.