The new family of high step ratio modular multilevel DC-DC converters

This paper presents a family of modular multilevel converters (MMCs) for high step ratio dc-dc conversion. The modular multilevel unidirectional step-down dc-dc converter topologies are presented. The high step-up ratio bidirectional modular multilevel dc-dc converter is also provided. Operation principle and analysis of the bidirectional dc-dc converter are shown, and verified by experimental results with a conversion ratio of 1 : 10. The proposed converters achieve high voltage step ratio depending on the number of sub-modules and the charging ratio.