Design and Simulation of Seven Level Cascaded H-Bridge Quasi Z Source Multilevel Inverter for Solar PV System

Power electronic converters, especially DC/AC Sinusoidal Pulse Width Modulation inverters have been extending their range of use in industry because of their numerous advantages. They typically synthesize the stair –case voltage waveform (from several dc sources) which has reduced harmonic content. This paper describes the development of design, modelling and simulation of the proposed seven level quasi-Z-source cascaded multilevel inverter (QZS-CMI) based PV systems which inherits the advantages of traditional CMI while overcoming issues with imbalance DC-link voltages. The modified inverter can produce a better sinusoidal waveform by increasing the number of output voltage levels. This paper also aims to analyse and compare total harmonic distortion in conventional cascaded three level, five level and modified seven level H-bridge inverters and evaluates THD in the respective outputs. Simulations of the circuit configuration have been performed in MATLAB/Simulink and the results were verified. KeywordsCascaded Multilevel Inverter (CMLI), quasi-Z-source multilevel inverter (QZS-CMI), Total Harmonic Distortion (THD), photovoltaic (PV) power system.