Investigation and comparison of cascaded H-bridge and modular multilevel converter topologies for medium-voltage drive application

This paper investigates the design procedure of cascaded H-bridge (CHB) and modular multilevel converter (MMC) topologies for medium-voltage and high-power industrial motor drive application. The design is performed using 1.7-kV insulated gate bipolar transistor (IGBT) technology. A model is derived for multi-pulse transformer to take into account its leakage parameters' effect on converter design. Also a comparison is done between MMC and CHB topologies at three different voltage levels: 4.16-, 6.9- and 13.8-kV and three different power levels: 1-, 3- and 5-MVA Comparison is done from several points of view like capacitance requirements, diode front-end and inverter stage losses, semiconductor rating and junction temperature and parts count.