A novel single-phase transformerless photovoltaic inveter connected to grid

A novel inverter topology for transformerless PV systems is proposed in this paper to meet the requirements of high efficiency, small size, light weight and low cost. The proposed inverter can guarantee not to generate the variable common-mode voltage, and the common-mode leakage current is nearly eliminated. Meanwhile, the three-level output voltage is achieved and only the same low input voltage is required as the conventional full-bridge inverter. Furthermore, not only the unipolar PWM but also the double frequency PWM can be both applied in the proposed inverter, and a lower ripple and a higher frequency of the filter inductor current can be achieved. Therefore, a smaller filter inductor can be employed and the copper losses and core losses are reduced greatly, or the higher quality and lower THD of the grid-connected current are achieved. At last, a 1kW prototype has been built and tested to verify the theoretical analysis of the paper.