A Grid Connected Photovoltaic System with a Multilevel Inverter and a Le-Blanc Transformer

Abstract- In this paper a novel power conversion structure for grid-connected photovoltaic applications is presented. This structure is based on a multilevel inverter and on a LeBlanc transformer. The proposed multilevel power converter uses two single-phase voltage source inverters and a four wire voltage source inverter. The Le-Blanc transformer is connected at the output of the multilevel inverter. The configuration of the PV system is based on the multi-string technology. The structural design of this new power converter allows a seven level shaped output voltage wave at the output of the multilevel inverter. To control this power converter a sliding mode controller with a vectorial modulator is used. This control system allows obtaining a fast a robust response for the multilevel inverter. Several experimental results are presented, confirming the expected performance of the proposed power conversion structure. Keywords- Photovoltaic power conversion; grid connection; multilevel converter; LeBlanc transformer; cascade structure; sliding mode controller. 1