Cascaded Stability Analysis of Modular Triple-Port DC/DC Converter for Next Generation of Vessel Integrated Power System

To interconnect the medium voltage dc (MVdc) bus and distributed energy storage elements (ESEs), modular triple-port DC/DC converter (MTDC) is recommended to shipboard applications due to its outstanding characteristics. MTDC is characterized by modular cascaded structure that composed of three kinds of sub-converters, which are modular multilevel converter (MMC), dual active bridge (DAB) and duplicated chopping circuit (DCC). The cascaded stability at the connection points of these converters requires investigation. This paper models the sub-converters of MTDC under different operating modes, and analyzes the closed-loop impedance of each sub-converter to figure out the cascaded stability of MTDC. Experiments has been implemented to validate the theoretical analysis.