An improved transformerless grid connected photovoltaic inverter with reduced leakage current and soft-switching technique

Transformerless inverters are widely used in grid-connected photovoltaic (PV) generation systems and induce leakage current due to the unstable common mode voltage and absence of galvanic isolation. However, transformerless inverter topologies have a lot of advantages, such as low cost, light weight, small size and high efficiency, but their semiconductor devices are still on hard-switching state at present, which normally has low efficiency, since the power losses across the switching devices are high. In this paper presents a novel Zero-voltage-transition concept for a new full bridge neutral point clamped (NPC) transformerless inverter, which has soft-switching technique and low leakage current. The proposed topology unite two coupled inductor along with series connected switch on AC side that operate alternately in positive and negative half period of grid. Finally, proposed topology is simulated by MATLAB/Simulink software to validate the accuracy of the theoretical analysis.