PV Cell Fed DC-AC Buck and Buck-Boost Inverter

Abstract

In this concept, two types of DC-DC converters with modified structures and different control methods for generating AC output voltage are proposed. In the modified cascaded dual buck inverter, absence of split capacitors leads to increased reliability of the inverter. Also, a new structure is proposed for integrated dual buck-boost inverter. The proposed inverters are capable of obtaining maximum power from solar cells by themselves. To evaluate operations of the proposed inverters, they have been modeled and simulated in PSCAD/EMTDC for different modulation indexes. Simulation results confirm validity and effectiveness of the proposed inverters.

AMONG various multilevel voltage-source inverters, the most commonly used and commercially available ones are the neutral-point-c1amped, flying capacitor and cascade H-bridge inverters. The cascaded inverters are capable of reaching higher output voltage level by using commercially standard lower voltage devices and components. They also feature a modular design concept which lessens the maintenance process and the cascade inverters are well suited for utility interface of various renewable energy sources, such as photovoltaic systems, fuel cells, battery energy storage, and electric vehicle drives, where separate DC Sources naturally exist. However, since most of cascaded inverters are based on a series connection of several single voltage source inverters (VSI) with two active devices in one leg, they suffer from shoot-through problems, which is the most dominating failure (drawback) of VSIs. In addition, for the hard-switched cascaded inverters operating at higher DC bus voltages, cause them to lose the benefit of using power MOSFETs as the active switching devices for efficiency improvement and fast switching speed when they are available at certain voltage and power level.The proposed concept is implemented to PV cell fed using matlab/simulink software.