Design of a Thrust Actuator for Magnetic Bearings With Low Radial Attraction Force

Thrust actuators are essential for magnetically levitated rotating machines to provide axial force for rotor balancing. Conventional designs generally consist of windings and iron cores. They produce very small radial force and the thrust density is low. Recent thrust actuator designs often integrate permanent magnets into the stator core to enhance the thrust density. However, considerable radial force may present if they are not designed carefully. The radial force produced by the thrust actuator is not desirable since it becomes a burden to radial actuator control. This paper presents a new thrust actuator design for magnetic bearings. The actuator can produce high thrust but low radial attraction force. The actuator force characteristics are analyzed using finite-element analysis. Experimental verifications are also performed.