Single Phase Integrated Ćuk Transformerless SiC Inverter for Grid-Connected PV Systems

This paper proposes a new single-phase transformerless inverter, using the principle of Ćuk converter for grid-connected photovoltaic (PV) systems. The new inverter has a common ground between the grid and the PV source, which helps to eliminate the leakage current in grid-connected PV application. Unlike common-ground type charge-pump based transformerless inverters, this topology eliminates inrush current and hence reduces the current stress on the components. Further, application of wide band-gap devices, such as SiC MOSFETs allows higher switching frequency to be achieved, and thus reduction of the size of the passive components. A novel switching strategy proposed here, allows current in both directions, positive and negative (to the load/grid or from the load/grid, for reactive loads), making the converter suitable for grid connection (unity power factor), as well as stand-alone operation with a reactive load. A prototype of the proposed converter has been fabricated, and experimental results has been presented also.