Multistring seven-level quasi Z-source based asymmetrical inverter

Abstract

In this paper, a single-phase multistring seven-level Quasi Z-source based Asymmetrical Inverter suitable for grid-connected photovoltaic (PV) system is presented. This topology is an upgrade of quasi Z-source dc-dc (qZs) network and Asymmetrical multilevel inverter (AMLI). The AMLI generates a higher number of levels with reduced switch count and number of sources when compared to symmetrical cascaded based MLI. The qZs network acts as an intermediate stage between the low-voltage PV array and AMLI, to enhance the output voltage gain of the inverter. The steady state performance of the topology is verified through MATLAB simulation and experimentation. A laboratory prototype model is developed for a capacity of 200 W to validate the theoretical studies. Finally, a comparative assessment of the proposed with the existing topologies is presented.