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Publication Date

Summer 2011

Degree Type

Thesis - Campus Access Only

Degree Name

Master of Science (MS)


Computer, Information and Systems Engineering


Sun Chiao

Subject Areas



This thesis is motivated in part by the lack of published research pertaining to

active magnetic thrust bearings (AMTB), as compared to active magnetic radial bearings

(AMRB). This thesis presents one method in implementing AMTBs to provide a near

frictionless support to a rotor contained in a vacuum environment, mitigating the

concerns of viscous drag and chemical reaction as a result of the exposure to lubricants.

An analytical model was first developed to linearize the AMTB against a predefined

operating point. A finite element simulation was subsequently conducted to verify the

analytical model. The analytical and finite element methods both indicated that the

steady state power consumption of the AMTB was approximately 12 W, and there was

no occurrence of magnetic saturation within the material. The stress analysis showed that

the stresses experienced by the rotor part of the AMTB as it rotated at the maximum

rotation speed were well below the yield stress of the material. Lastly, a closed loop

feedback network with proportional-integral-derivative (PID) controllers was designed

and implemented as the control scheme for keeping the flywheel rotor at a predefined

axial position, while the rotor underwent axial position variations due to the external

disturbance, thermal expansion, or Poisson contraction effects. The resulting simulations

showed that the PID controller was able to stabilize the flywheel rotor 0.3 s after it was

disturbed by an external force equaling 10% of its weight.