Evaluation of DC-AC single-phase solid-state transformers

Abstract

This work presents an evaluation of three topologies of DC-AC single-phase solid-state transformers, for applications in electric microgrids. The main features of these topologies are galvanic isolation, capability to control the power flow bidirectionally, soft switching and unit power factor under open loop control. The principle of operation of each topology is described and the modulation strategy used is detailed. A comparison of the THDi of the current waveform injected into the grid, the power factor and the utilization factor of the semiconductor switches for each topology is presented. As a result, the most suitable topology for the integration of microgrids with high penetration of renewable energies to the grid is determined. Simulation results are presented to validate the theoretical analysis.