Active Magnetic Bearings and Self-Bearing Motors

This dissertation covers aspects of modeling and control of magnetic levitation devices, specifically, active magnetic bearings (AMBs) and self-bearing motors (SBMs). Chapters 2-4 focus on AMBs and how they are used to levitate high-speed rotating shafts in a variety of applications. First principle modeling, parameter identification, and feedback control designs are discussed and demonstrated in practice on a commercially available test stand. Various control approaches are presented to achieve basic stabilization, vibration suppression, and trajectory tracking. An SBM, which simultaneously levitates and rotates a shaft, is used to integrate an AMB with an electric motor for the sake of compactness and economy. This dissertation focuses on recent developments in SBM design which utilize the Lorentz force as the basis for levitation, in contrast to AMBs which establish levitation on more common basis of Maxwell force. SBMs are the topic of Chapters 5-7, with emphasis on levitation force and motoring torque characterization, dynamic modeling, and feedback control approaches necessary to drive robust performance.