New topology to reduce leakage current in three-phase transformerless grid-connected photovoltaic inverters

Three phase converters are favorable for high power grid connected systems. In photovoltaic (PV) application, it is possible to remove the transformer from the PV system in order to reduce size, losses, and cost; and improve the efficiency. In other hand, presence of the parasitic capacitor between the panel's metal frame and cells causes the leakage current issue. The leakage current increases current harmonics injected into the utility grid, the radiated and conducted electromagnetic interference, and losses. In this paper, a novel grid-connected inverter topology with an optimum modulation technique is proposed to address leakage current issue. The proposed topology also improves output current THD in three-phase transformerless PV inverters. Moreover, the proposed topology is compared by traditional three phase inverter in terms of common mode leakage current and output current THD. In reference to MATLAB/SIMULINK simulation results, the proposed topology is able to reduce the common mode ground leakage current and improve the output current THD by 2.17%.