A Reliable Three-Phase Transformerless Grid-Connected PV Inverter With Inductive DC Link

In this paper, a modified buck-boost grid-connected three-phase photovoltaic inverter is presented. In the structure of inverter, an inductive dc link is used between the input and output. The merits of the employed inverter are soft switching and step-up/down conversion without any additional power converter stage. It is a transformerless inverter with no leakage current issue. Moreover, as a result of increased switching frequency, it offers output current total harmonic distortion within standard limits. It uses only one current sensor and there is no electrolytic capacitor in it, which leads to high reliability. The operating principle is thoroughly explained and a simple control strategy with a new maximum power point tracking (MPPT) algorithm is proposed. The simulation and experimental results are provided to verify the behavior of a modified inverter, its control strategy, and the MPPT method.