Development of modular solid-state transformer based on distributed control

A solid-state transformer (SST) is a power electronics converter that converts high voltage alternating current to low voltage alternating current and it aims to replace conventional 60 Hz power transformers. The SST has been regarded as one of the most emerging technologies in power distribution systems. Transferring energy through a high-frequency transformer with power electronics brings SST advantages of low volume, low weight, fault isolation, and potential additional functions, such as voltage regulation, harmonic filtering, reactive power compensation, etc. However, the involvement of a large number of power devices makes the control of an SST a challenge. In addition, the high voltage and high-power hardware design of the SST are not easy. To resolve these issues, this research seeks to develop a modular solid-state transformer (MSST). Specifically, the overall SST system is built by multiple identical isolated AC/AC converter modules connected in an input-seriesoutput-parallel configuration. Also, a distributed control algorithm has been developed for MSST to further increase modularity. The proposed solution of SST significantly reduced the overall system complexity and cost. Compared to previous research on SST, MSST improves both conversion efficiency and power density. The modular architecture allows more flexibility on converter module design optimization. Therefore, optimization of the isolated DC/DC converter stage is studied in this research. The hardware implementation and a distributed control algorithm will be illustrated in detail. Simulation and experiment results will be shown to demonstrate the feasibility and performance of MSST.Electrical and Computer Engineerin