Increasing resolution in three-phase cascaded asymmetrical multilevel inverters

Asymmetrical cascaded multilevel converters can generate more number of voltage levels for the same number of switching devices. Binary, Trinary and other different forms are available in literature. This paper has critically investigated such converters from the point of view of optimizing the number of levels. A mathematical tool to analyze the possibility of any asymmetric ratio for various three-phase topological configurations is developed. This mathematical tool is then used to find the ratio of asymmetry for three phase cascaded multilevel converters. Operation of the identified asymmetry is validated through simulation and experimental results using laboratory prototype.