Design and Implementation of Asymmetric Multilevel Inverter and Auxiliary unit Based High Gain Converter for Enhanced Grid Connected Solar Photovoltaic System

Abstract

In grid-connected solar photovoltaic rooftop systems, the solar newlinephotovoltaic system voltage is much lower than the grid voltage. newlineTherefore, the transformer is a mandatory portion of stepping the voltage newlinelevel to meet grid voltage for integration. Hence, the cost and size of the newlinesystem become higher, and many single-phase customers are not coming newlineforward to install grid-connected solar rooftop systems. Multilevel newlineinverters and high-gain DC-DC converters are alternative solutions to newlineovercome these drawbacks in grid-connected solar rooftop systems. This newlineresearch proposes a five-level asymmetrical multilevel inverter and a newlinehigh-gain DC-DC converter. The operating principles of the proposed newlineinverter and converter are analyzed and implemented for grid-connected newlinesolar photovoltaic systems. The hysteresis current control technique newlineintegrates solar photovoltaics and grid with the proposed five-level newlineasymmetrical multilevel inverter. A conventional five-level cascaded H- newlineBridge multilevel inverter requires eight switches and two DC sources to newlineproduce a five-level output voltage. The proposed five-level multilevel newlineinverter developed with six switches and a single DC source. The newlineproposed system helps improve the voltage level higher than single-phase newlineVSI. newlineFor solar photovoltaic modules with lower voltage or systems newlineoperated with fewer photovoltaic modules, the conventional DC-DC newlineconverter must be operated with a higher duty ratio to meet the grid newlinevoltage level. However, the conventional boost converter operated at newlineexcessively high duty ratios might push the converter beyond its optimal newlineoperating range, leading to instability or failure. newlinevi newlineTo overcome the drawback mentioned above, proposed an newlineauxiliary unit-based high-gain DC-DC converter for DC grid integration newlinewith solar photovoltaic systems. This research describes the detailed newlinecontinuous conduction mode and discontinuous conduction mode newlineoperations for proposed high-gain converters. The mathematical analysis newlineunder each operating state is reported in this research.