Design of a Non-Isolated Three-Switch Inverter for Renewable Energy Systems, Featuring Simple Circuit, Continuous Output Current, Common Ground and Buck-Boost Operation

Compared to the transformer isolated photovoltaic (PV) inverters, majority of the non-isolated PV inverters can achieve higher efficiency. In addition, they can have lower weight, cost and size. However, the non-isolated PV inverters must be designed carefully and properly to limit the common-mode leakage current between the PV arrays and the grid to a maximum allowable legal value.The output voltage of the PV arrays varies in a wide range with temperature, light, environment, and so on. Therefore, the PV inverters should adapt to the wide voltage range. In order to address the above two issues, this paper presents a novel non-isolated PV inverter for PV applications, which do not generate leakage current and have the buck-boost ability. The simple circuit topology and operation makes the proposed inverter a strong candidate for the renewable energy systems especially PV applications. Theoretical analysis followed by the experimental results is provided to verify the performance of the proposed inverter.