Abstract:The transformerlsee photovoltaic (PV) unipolar SPWM full-bridge inverter with ac bypass brings low conduction loss and improves common-mode performance. In order to eliminate leakage current induced by common-voltage, the clamping technology is adopted to clamp common-voltage to a constant value. An improved inverter topology and modulation strategy has been proposed in this paper, two independence freewheeling paths and two diodes are added into the ac side of full bridge inverter. And then, the SiC-IGBT is adopted in the inverter to eliminate the reverse recovery problem. As a result, the efficiency can be significantly improved. The operation mode, differential-mode and common-mode characteristics of the proposed inverter are analyzed in detail in this paper. Finally, the performance of the proposed topology is verified by a prototype inverter rated at 3kW and 50kHz.