Configurations of slotless permanent magnet motors with counter-rotating rotors for ship propulsion drives

This paper describes configurations of permanent magnet motors with counter-rotating rotors. This machine topology can find applications in marine propulsion systems that use additional counter-rotating propeller in order to recover energy from the rotational flow of main propeller stream. In this case the use of a PM motor having counter-rotating rotors allows the elimination of the motion reversal epicyclical gear. For these kinds of motors, the ship propulsion drives is a very interesting application, especially for contra-rotating propeller. PM rotors do not have magnetisation losses, which simplifies the rotor construction and cooling. This can be very useful in slow speed and podded drives where a motor is installed in the propeller pod, and where space savings can bring significant benefits. Innovative applications of maritime object’s drives constructions with slotless disc and two type cylindrical counter-rotating electrical machines based on permanent magnets were proposed. In this study, differen permanent magnet motor configurations were analyzed. Numerical calculations of motor characteristics were performed with a three-dimensional finite element, timestepping simulation program (Flux3D). Results of simulations of disc type machine were verified with experimental measurements conducted on physical model.