08-09-2017, 10:38 AM
To eliminate the common mode leakage current in the system connected to the transformerless photovoltaic network, an improved single-phase inverter topology is presented. The improved transformerless inverter can withstand the same low input voltage as the full bridge inverter and ensure that it fully complies with the common mode leakage current elimination condition. Both unipolar sinusoidal pulse width modulation (SPWM) and dual-frequency SPWM control strategy can be applied to implement the three-level output in the submitted inverter. The high efficiency and the comfortable thermal design are achieved by the decoupling of two additional switches connected to the DC side. In addition, the higher frequency and lower current ripples are obtained by adopting the dual frequency SPWM and, therefore, the total harmonic distortion of the current connected to the network is considerably reduced.