A two-stage AC/DC SST based on modular multilevel converterfeasible to AC railway systems

This paper proposes the use of the modular multilevel converter (MMC) for ac-dc conversion using medium frequency transformers in a two-stage topology with unidirectional switches. The losses analysis of the propose converter are presented with a comparative studyamong others two topology well know in the literature for traction applications. The basic description of the topology and some simulation results are presented, followed by a comparative losses result.