Isolated bidirectional DC-to-three-phase AC converter for integration of renewable energy sources to electric grid

Abstract

In this study, a new isolated bidirectional DC-to-three-phase AC converter for integration of renewable energy sources to the electric grid is presented. The main features of this topology are galvanic isolation, capability to control the power flow bidirectionally, soft switching, unit power factor under open-loop control and also allow step up and step down the voltage. Its operation principle is described and a modulation strategy is proposed, which allows to control the power flow according to the requirements of the load and to operate with minimum switching losses owing to the soft switching. The results revealed the feasibility of the proposal with a THDi of the AC current waveforms below 5% and the power factor above 0.98.