Fault tolerant three-level boost inverter with reduced source and LC count

Abstract

Presently single stage boost multilevel inverters are becoming more popular for power conversion in renewable energy systems, AC-DC hybrid microgrids etc. Usually in these boost inverter the voltage stress across the inverter leg switches as well as current through these switches are quite higher as compared to load ratings which increases the chances of inverter leg switch failure. In this paper a three level voltage source boost inverter is proposed to achieve rated three level AC output voltage in a single power conversion stage. It retains all the advantages of three level quasi Z- Source inverter by using less number of passive components in the intermediate network between DC source and inverter leg. Beside the inherent shoot through fault tolerant feature the proposed inverter is capable to operate in open circuit failure to give rated balanced AC voltage at load. The above advantages of the proposed single stage inverter make it suitable for low and medium power renewable energy applications where size, weight are main constraint and some of the critical loads are connected to the system. The proposed inverter is verified by simulation (in MATLAB Simulink) and experiment with the help of a laboratory prototype.