A New Grid-Connected Asymmetrical Multilevel Converter for PV Application

In this article, an asymmetrical multilevel inverter (MLI) for employment in PV systems is introduced. Using a unidirectional isolated dc–dc converter at the input of the system, in addition to increasing the PV voltage level, prevents reverse power flow and can be used in high-power applications. This converter also isolates the PV source from the grid through a high-frequency transformer. The dc link of the system is connected to the grid by the proposed 25-level inverter, which significantly reduces the size of the grid inductor. Most switches of the proposed inverter operate at the fundamental and low frequencies, and the capacitors comprise the ability of self-balancing voltage. Also, the isolation between the sources of the proposed inverter can be done through a low-power isolated dc–dc converter. In addition to reducing the number of isolated sources, this converter always maintains the ratio between the inverter sources and stabilizes the quality of the output voltage. The injection of active power into the grid is managed by the proportional-resonant controller. Also, it is possible to exchange reactive power with the grid by the bidirectional proposed inverter. The proposed inverter is simulated in MATLAB software for verification and then implemented experimentally.