A New Four-level Transformer-less Single-phase Inverter for Grid-connected Photovoltaic Systems

Because of the characteristics of high efficiency and low cost, the transformer-less photovoltaic (PV) grid-connected inverters have been popularized in the application of solar electric generation system in residential market. However, in these inverters the ground leakage current through the stray capacitors between the PV array and the ground is harmful and causes losses and electromagnetic interference. This paper presents a new four-level single-phase inverter for grid-connected photovoltaic systems with a low leakage current. The proposed inverter can operate in non-unity power factors. For minimizing the leakage current, a switching control strategy is presented. The simulation results verify the superiority of the proposed inverter structure.