Unidimensional modulation technique for cascaded multilevel converters

This paper presents a simple and low computational cost modulation technique for multilevel cascaded H-bridge converters. The technique is based on geometrical considerations considering an unidimensional control region to determine the switching sequence and the corresponding switching times. In addition, a simple strategy to control the dc voltage ratio between the H-bridges of the multilevel cascaded converter is presented. Examples for the two-cell topology are shown but the proposed technique can be applied to develop modulation methods for a higher number of H-bridges. Experimental results are presented to validate the proposed technique.