Novel high-speed, Lorentz-type, slotless self-bearing motor

Active magnetic bearings are a preferred choice for supporting rotors spinning at high-speed due to low friction losses and no wear. However, the rotational speed in previous bearing topologies has been limited by complex rotor constructions, high rotor losses, or position control instabilities at high speed. This paper presents a novel Lorentz-type, slotless self-bearing motor concept which overcomes most limitations of previously presented high-speed AMBs. An analytical model for motor torque and bearing forces is presented and a design for 500 000 rpm is verified with FE simulations, showing exceptionally low negative stiffness cross coupling. Finally, a prototype system is described.