Electric Propulsion System with Hybrid Powertrain Equipped with Diesel/Gas Generators and Battery-Buffered AC Common Bus for LNG Ships

In the contemporary maritime industry, energy-efficient operations on ships are increasingly prevalent, motivated by mandatory regulations from sector-leading organizations aimed at reducing carbon emissions. Electric propulsion systems are an alternative solution to further enhance energy efficiency by ensuring optimum power flow between alternative sources and common busbars. This study presents an electric propulsion system with hybrid powertrain for an LNG ship and its power management system. The powertrain is composed of a common AC busbar, diesel generator, LNG generator, battery, and electric motors. The relevant system has the advantages of having an energy storage system to supply critical loads under challenging conditions and prioritizing the use of LNG instead of diesel generators, thereby reducing COx emissions. Additionally, it encompasses synchronization challenges brought about by the use of multiple power sources. The synchronization of these diesel and LNG generators to the battery-buffered common AC bus presents its own challenging issues. In this study, both the energy-efficient electric propulsion system layout and the power management system that ensures low-emission and efficient system operation have been described.