A fully-integrated fault-tolerant multi-phase electric drive for outboard sailing boat propulsion

Marine transportation electrification is a technology process which is presently transforming large cruise and cargo ships, mega-yachts and military vessels. The proposed paper reports on a research project intended to fully electrify sailing boats by replacing the traditional internal combustion engine, used for maneuvering and emergency or weak-wind navigation, with an electric battery-fed fully-integrated outboard propulsion system, based on a four multi-three phase machine. The developed technology combines the propeller, the electric machine as well as the control and power-electronics apparatus into a compact, bidirectional and fully-integrated electric drive. An innovative design procedure for the electric machine windings allows a complete magnetic decoupling of each three-phase sections. An innovative control technique is also introduced, allowing complete decoupling of the control action among the different three-phase sections of the machine in case magnetic coupling is present, i.e. with a standard machine design. The main stages and aspect of the technology developments are being illustrated in the proposed paper along with the results achieved in the prototype design, construction and testing.