Abstract
A semi-two-stage common-ground-type transformerless dual-buck-based grid-connected inverter is proposed in this paper. The common-ground-type topology can eliminate common mode (CM) leakage current by connecting the negative terminal of the photovoltaic(PV) directly to the neutral point of the grid, which bypasses the PV array's stray capacitance. The dual-buck-based topology guarantees increased robustness since the dc-link cannot be short-circuited by a shoot-through event. The semi-two-stage topology features multi-level characteristic, which has a lower forward-voltage drop and smaller dv/dt. Compared with the conventional two-stage inverter, the proposed topology achieves higher efficiency and higher reliability. Experimental results of a 1.5kW prototype show that the proposed inverter is able to achieve high efficiency and low leakage currents.
Highlights
Since the energy crisis and environmental pollution problem is becoming increasingly serious, solar energy, wind energy, fuel cell and other new energy power generation technologies have been paid more attention to [1-3]
Because of the common-ground type structure, the common mode leakage current to the grid is eliminated by connecting the negative terminal of the PV directly to the neutral point of the inverter
(2), (3), it is known that the common-ground-type inverter can almost eliminate the common mode leakage current iCM
Summary
Since the energy crisis and environmental pollution problem is becoming increasingly serious, solar energy, wind energy, fuel cell and other new energy power generation technologies have been paid more attention to [1-3]. Because of the common-ground type structure, the common mode leakage current to the grid is eliminated by connecting the negative terminal of the PV directly to the neutral point of the inverter. Dual-buck structure cells, as shown in Fig.[2], with its high reliability, have become a research hotspot of many scholars in recent years[17-22]. Considering these aspects, a novel commonground-type five-level semi-two-stage dual-buck inverter is investigated in this paper for PV applications. It increases the efficiency and reliability of two-stage grid-connected inverter. Zhang et al.: Two-Stage Transformerless Dual-Buck PV Grid-Connected Inverters with High Efficiency 37
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