A High-Voltage Gain Transformerless Grid-Connected Inverter

Transformerless inverters are used in small and medium power photovoltaic grid-connected systems due to small-size, low-cost and high-efficiency. Transformerless inverters have problems of leakage current and low-voltage gain in applications due to the lack of electrical isolation and boost characteristics of transformers. According to these problems, this paper introduces a gain unit circuit in the front-stage based on the two-stage topology of Boost converter combined with the H-bridge inverter to improve the boost capability. The rear-stage adopts double Buck inverter, which has the ability to prevent the short circuit of the bridge arms and improves the reliability of the system. At the same time, it is ensured that there is no high-frequency component in the parasitic capacitance voltage, and the leakage current is suppressed. In this paper, the operational modes, circuit gain and devices stress of the proposed inverter are analyzed, and the simulation verified the feasibility of the scheme.