AC solid-state transformer using DC-DC converters and without added rectifier and inverter stages

Solid-state transformers (SSTs) typically use several power electronic stages - a front-end rectifier, followed by a high frequency transformer-isolated DC-DC converter, and then an inverter. These multiple conversion steps result in a high component count and complexity. In contrast, this paper presents a novel topology for AC SSTs that solely uses isolated DC-DC converters and does not require additional rectification/ inversion stages. Simulation results and experimental verification with a three-phase AC prototype using series resonant DC-DC converter blocks are presented. The proposed SST can be used as a compact substitute for line-frequency transformers in space-constrained applications such as EV charging stations, wind turbine nacelles, and urban power distribution systems.