Aerodynamic Bearing-Equipped High-Speed PM Motor with Auxiliary Levitation and Extra Torque

In high-speed motor systems, aerodynamic bearings can generate support to the rotor without external air supply, due to the dynamic pressure effect during the rotor motion. However, there is dry friction between the static and moving surfaces of the bearing before it reaches the lift-off speed. In this paper, it is proposed to add an auxiliary winding in the motor so as to provide auxiliary levitation before lift-off to reduce the dry friction, and then generate extra torque as an additional armature winding while the bearing is working at high speed. The auxiliary winding structure and operation principle are detailed hereafter. Moreover, analytical derivation and finite element method (FEM) verification are elaborated.