A novel structure for multilevel converters

Abstract

In this paper a new structure for asymmetric multilevel converters is presented. The new topology is consisting of N series-connected of two interconnected multilevel converters per phase. The presented circuit is an optimized multilevel converter with minimum DC voltage sources and switches. The investigated topology can generate a large number of levels (odd and even) without increasing the number of switches and DC voltage sources. For this structure a new algorithm for calculating the levels of DC voltage sources is proposed. Also a complete analysis is given for calculating the harmonic distortion and THD. The proposed converter has higher efficiency because the number of switches is reduced and the devices which can be switched at low frequency. Then for showing the ability of the proposed converter, we use this converter as the core of a DVR, which is based on this converter. This DVR has been modeled and the simulation results show that the DVR can solve power quality problems such as: voltage sag, voltage swell, unbalanced and distorted voltages