Control of a six-switch inverter based single-phase grid-connected PV generation system with inverse Park transform PLL

This paper designs and analyzes the switching strategy and control schemes for a six-switch grid inverter based single-phase photovoltaic (PV) power generation system. Such six-switch PV grid inverter not only offers good grid current performance, but also enables low leaking current for the transformerless grid-connected PV system. With the inverse Park transform based PLL technique, the proposed control scheme in this paper can adapt the change in grid voltage and frequency effectively. Meanwhile, the PV power generation system can switch between the single-stage operation and the two-stage operation modes by controlling the boost converter, which links the PV modules and the grid inverter. The experiments on a 1.5kW laboratory setup have verified the good system performance in the steady-state operation, the starting process, the PV curve change, the operating mode switching, and the grid frequency adaptation.