Study on Counter-Rotating Dual-Rotor Permanent Magnet Motor for Underwater Vehicle Propulsion

This paper proposes a counter-rotating dual-rotor permanent magnet synchronous motor to drive two counter-rotating propellers of a cylindrical underwater vehicle. This can avoid yawing and spinning of the underwater vehicle whilst maintain excellent electromagnetic performance. Because of a direct drive arrangement, the system efficiency of the motor drive is improved as well as the volume and costs. More importantly, the proposed motor has better reliability than conventional underwater dc drive systems owing to the removal of brushes and slip-rings. In electromagnetic design, the pole number, permanent magnet size, stator winding design, and nonmagnetic material are analyzed and optimized. Finally, a 10.8 kW 1000 r/min counter-rotating dual-rotor disc-type PM motor is designed, and its main performance parameters, such as EMF, torque, and mechanical stress, are analyzed, which have confirmed the effectiveness of the rotor design and its application to underwater propulsion applications.