Tree Shaped Converter with High Modularity, High Power Density and High Extendability for the Second-Generation Vessel Integrated Power System

The second-generation vessel integrated power system (IPS) is characterized by more diversified energy ports with different voltage levels. The traditional distribution scheme based on a common medium voltage DC (MVDC) bus introduces complex and bulky MVDC converters. To overcome this problem, this paper proposes a novel tree shaped converter (TSC) providing low-voltage DC (LVDC) buses with multiple voltage levels. TSC features high modularity, high power density and high extendibility, which is constructed by connecting cascaded half-bridge converters (CHBCs) of different ratings at the submodule (SM) capacitors in a hierarchical manner. Fundamental topology, operating characterization, imbalance boundary and control strategy are studied and validated with simulation.