Three-Phase Four Wire High-Frequency Link Converter for Residential DC Grids

There is increasing penetration of dc native renewable technologies, such as batteries and photovoltaics in the distribution grid. These renewable technologies can be interconnected with dc microgrids, which in turn often have a bidirectional connection with the ac distribution grid to enable energy exchange. For safety reasons, this connection is often galvanically isolated with a transformer. This paper presents a single stage high frequency link converter, based on an indirect matrix converter. A three leg four wire configuration is proposed to be able to operate in unbalanced conditions and provide various ancillary grid services. A digital controller is developed to control the grid currents and eliminate distortion at the zero crossing of the matrix converter. The results are verified with a PSIM model.