An innovative bidirectional isolated multi-port converter with multi-phase AC ports and DC ports

This paper presents an innovative bidirectional isolated multi-port converter with multi-phase AC ports and DC ports, which is a key element of Solid-State Transformers (SST) utilized for example in a wind energy generation system. The multi-port converter allows the direct coupling of the three-phase AC system of the power generator with the three-phase AC utility grid and an additional DC storage unit applying a single high-frequency transformer structure. The topology is stackable and hence, single converter modules can be connected in series at the input/output ports for medium or high voltage or in parallel for low voltage applications. The converter is operated utilizing a time-varying phase-shift control to draw or inject sinusoidal currents with a corresponding amplitude and phase at the AC ports. The topology, its operating principle including the theoretical analysis and simulation results of a prototype system are provided.