Three-phase transformerless grid-connected photovoltaic inverter to reduce leakage currents

Transformerless grid-connected PV inverter is widely used recently because it is smaller in size and highly efficient. Nevertheless, high leakage current flows between the PV array and the grid due to the parasitic capacitance. To overcome this problem, several conversion topologies and modulation techniques have been proposed recently. However, these lead to additional cost and low efficiency due to very low modulation index while improving the common behaviour. This paper is to propose a new three-phase transformerless topology without using complicated modulation techniques and expensive components. Only one extra switch is added. The operation and common mode (CM) performance of the proposed topology is discussed. The analysis and the performance are verified via simulation results.