Adaptive Backstepping Control Of Cascaded H-Bridge Multilevel DC/AC Converters

Abstract

This paper aims at highlighting on the importance of the cascaded H-bridge multilevel inverter in overcoming the disadvantages of the conventional multilevel inverter by combining three H-bridge modules together so as to increase the power level. The three H-bridge modules, which are empowered fundamentally by an H-bridge module, generate seven voltage levels as output. This topology can be used for large-scale PV conversion systems (> 10MW), electric vehicles (EVs) or hybrid EVs through a hybrid control of cascaded H-bridge multilevel inverters, where each module of the inverter can be supplied using a DC source, found mainly in fuel cells, batteries, photovoltaic systems or ultra capacitors. Our main focus in this paper is to provide sinusoidal voltages with very low harmonic distortion to be used in an Uninterruptable Power Supply (UPS) system. The three-cell H-bridge inverter is commanded by PWM generators and controlled by two types of regulators. The first one is the nonlinear backstepping approach and the second one is the adaptive backstepping approach. The structure under investigation is analyzed using MATLAB/SIMULINK environment.