A Contra-Rotating Magnetically Geared Thruster

This paper presents the magnetic design of a new type of magnetically geared contra-rotating water thruster. To create contra-rotation the two outer rotors of the magnetic gear are connected to propellers and the inner rotor of the magnetic gear is driven using a high-speed motor. The reaction torque is provided by the propellers drag. The magnetic gear’s field modulation results in the two high torque outer rotors contra-rotating. A finite element analysis based magnetic design is presented along with a torque ripple analysis. The presented torque ripple reduction study includes an axial slicing analysis and a modulator slot shaping analysis. An experimentally constructed proof-of-principle prototype design is also presented.