Hybrid drives for naval auxiliary vessels

The introduction of affordable and reliable Active Front End (AFE) power electronics technology now enables the marine Power and Propulsion (P&P) designer to employ a hybrid design to achieve efficient electric drive for cruise speeds and cost effective mechanical drive for faster speeds. The electric drive allows the Main Diesel Generators (MDG) to provide power to Ships Electrcial Load (SEL) and the propulsion motors whilst those same motors operate as alternators when running on the Main Diesel Engines (MDE) at higher speeds. The design leads to fewer prime movers, fewer engine running hours and also fuel economy compared to the usual alternative designs: full mechanical and full electrical. BMT have recent experience of how such a design is achieved. In this paper a typical naval auxiliary vessel is used as an example to demonstrate the benefits of a hybrid design and some of the issues involved in its implementation.