Multiphase Multilevel NPC Converter for MVDC Electric Ship Applications

Electric propulsion has been used in marine systems for a while, but it was the availability of power electronic converters that allowed for the electrification of large ships. MVDC power systems have become of interest for future low emission, fuel-efficient vessels, but they require effective analysis tools due to their complexity. Modeling and simulation are essential to design, analyze, and optimize the system. This paper proposes a multi-phase multi-level power electronics-based converter for medium voltage DC electric ship applications, along with a generalized framework for multiphase multilevel space vector modulation (MPML-SVM) technique to control the converter effectively. The proposed approach is based on a hierarchical method that involves SVM basic calculations, SVD for MPML-SVM, and integration of parametrized calculations and SVD to solve dwell time equations and extract switching signals. Simulation studies are performed and compared for MPML converters in a medium-voltage electric ship system (MVESS) to validate the analytical models under different conditions.