Single-phase ac–dc–ac multilevel five-leg converter

In this study, a multilevel five-leg single-phase ac-dc-ac converter and its generalisation are presented. The converter is suitable to be used as an uninterrupted power supply or a unified power quality conditioner without an isolation transformer. The operating principles, the pulse-width modulation strategy and the control system for the proposed converter are presented. The proposed single-phase multilevel ac-dc-ac converter is composed mostly of low-power switches capable of generating input and output voltages with low harmonic content. The proposed configuration is compared with the conventional solution in terms of harmonic distortion, semiconductor losses and ratings of switches. Experimental results demonstrate the feasibility of the proposed configuration. The experimental verification of the proposed topology and control strategy was obtained by using IGBTs with dedicated drives and a digital signal processor TMS320F28335 with plug-in boards and sensors.