Serial Peripheral Interface Based Primary Layer Control of a Solid State Transformer

The solid-state transformer (SST) is a developing technology which is being integrated in low and high-voltage power systems, supporting the integration of renewable energy in smart grid applications and fast charging stations for electric vehicles (EV). SST is becoming more critical in certain applications of advanced power distribution systems as it provides several advantages over the conventional transformer including its controllability, small weight and size, potential low cost, and simplicity of connection for offshore wind farms. However, some challenges arise in modular SST design and implementation including control architecture for equal power balancing, protection, and communication compatibility that need to be addressed. This paper provides an overview of different SST communication protocols and offers prospects, applications, and future directions for research and development. A control architecture for input and output voltage balancing is presented for a direct power conversion (DPC) type SST system. A detailed SPI communication protocol is also provided which allows the implementation of decentralized operation of the modular SST system.