Single-Stage Multiport Capacitive-Link Universal Power Converter as a Solid-State Transformer for Nanogrid and Microgrid Applications

This paper presents a single-stage capacitive-ac-link multiport power converter, which can function as an interface for interconnection of different types of sources and loads, dc or ac, in multi-input/multi-output systems and solid-state transformer (SST) applications. The proposed single-stage converter topology can actively manage the power flow between the sources and loads. This converter transfers the energy through a small high frequency capacitive-ac-link, which eliminates the need for electrolytic capacitors. If galvanic isolation is required a compact high frequency transformer can be added to the link. In this paper, a multiport system with a three-phase ac input source, one three-phase ac load, one photovoltaic (PV) source, and one battery energy storage system is considered to investigate and study different power flow scenarios in the proposed converter. The simulation and experimental results verify the promising features of the proposed single-stage topology as a multiport converter.