Cascaded Stability Assessment Methodology of Modular Triple-Port DC-DC Converter for the Next-Generation Vessel Integrated Power System

The modular triple-port DC-DC converter (MTDC) is recommended as the energy router for DC power distribution of the vessel integrated power system, and the stability assessment of MTDC is an issue of concern. However, the interactions among different branches are so significant that the conventional criterion may not have the ability to judge stability readily. Thus, research work related to stability analysis of MTDC is further explored, and a new criterion for MTDC is presented in this article. Firstly, the basic principle of MTDC is introduced, such as the topology, operating modes and control strategies. After that, the port impedances of all sub-converters are given, including the transfer functions of the port current to the non-corresponding port voltage in other branches. The small-signal model of the cascaded system is obtained by considering the system as an interconnected network. Then, the equivalent loop gains are precisely derived which indicates the cascaded stability criterion of MTDC. Finally, experiments were conducted in a 10 kW/500 V MTDC engineering prototype to verify the effectiveness of proposed stability assessment method.