Modified Topology for Three-Phase Multilevel Inverters Based on a Developed H-Bridge Inverter

Abstract

This paper proposes a modified three-phase inverter from the developed H-bridge structure having multilevel functionality. The proposed topology can generate 7-levels of phase voltages and 13-levels of line voltages. Simple control methods such as fundamental frequency control method can be applied to the proposed topology. By adding three single-phase transformers, galvanic isolation is created for use in three-phase Dynamic Voltage Restorer systems. The proposed three-phase inverter utilizes less number of components; dc sources, semiconductor switches and driver circuits. Lower rated power switches with reduced blocking voltages are also used. These attributes make the proposed topology less complex in-terms of architecture and control. Comprehensive analysis of the proposed three-phase multilevel inverter and other presented topologies are investigated with respect to levels of output voltage, driver circuit quantity, dc voltage count, total component quantity and standing voltage. Details of the appropriate control technique employed is explained. Finally, practicability of the proposed inverter is validated by simulation using EMTDC/PSCAD software and experimental prototype.