Single phase transformerless semi-Z-source inverter with reduced total harmonic distortion (THD) and DC current injection

A single phase transformerless semi-Z-source inverter topology is presented in this paper in order to incorporate distributed photovoltaic generators to the grid with reduced total harmonic distortion (THD) and DC current injection. These proposed inverter topologies are capable of achieving the sinusoidal output voltage by using only two active switches whereas the traditional inverters require four. A modified form of nonlinear SPWM technique is employed here to overcome the nonlinear voltage gain problem of semi-Z-source inverter for providing desired duty cycle which generates the sinusoidal voltage at the output. This inverter topology shows less DC current injection to the grid. Furthermore, common ground is being shared by both DC input and AC output voltage; hence common mode leakage current gets mitigated. Finally, a prototype rated 50W is constructed and a verification of theoretical outcome with the results of the experimental setup are presented. The results of the experiments satisfy the effectiveness of the aforementioned topology.