An Axial Flux Double-Rotor Counter-Rotating Permanent Magnet Machine for Underwater Vehicles

The research on the counter-rotating motor which can be used to drive the counter-rotating propeller is of great significance to improve the dynamic performance of underwater vehicles. This paper proposed an axial flux counter-rotating motor (AFCRM) with two counter-rotating rotors and a modular stator which can eliminate the brushes and slip rings, and at the meant time offer better torque density. The 2D linear motor model based on the equivalent magnetic reluctance in the magnetic circuit was proposed to analyze the AFCRM with an acceptable accuracy. And the electromagnetic performance of the AFCRM were analyzed and adjusted using the proposed 2D model. The magnetic fields on both sides will be periodically in series or in parallel, which causes the back EMF distortion and torque ripple, so a tooth and slot offset structure of the AFCRM was proposed. Finally, the advantages of AFCRM are presented by comparing AFCRM with the other two solutions for the counter-rotating propeller underwater vehicles.