Symmetrical Hybrid Multilevel DC–AC Converters With Reduced Number of Insulated DC Supplies

Novel symmetric hybrid multilevel topologies are introduced for both single- and three-phase medium-voltage high-power systems. The topology conception is presented in detail, where a three-level switching cell with low component count, and its modulation pattern give the origin of the proposed converters. Voltage sharing and low output-voltage distortion are achieved. The theoretical frequency spectra are derived. Switching devices are separated into high- and low-frequency devices, generating hybrid converters. Five-level three-phase topologies are generated from only three insulated dc sources, while the number of semiconductors is the same as for the cascaded H bridge. Both simulation and experimental results are provided showing the validity of the analysis.