Title page for ETD etd-0405103-131627

Type of Document Master's Thesis
Author Motee, Nader
Author's Email Address nmotee1@lsu.edu
URN etd-0405103-131627
Title Minimization of Power Losses in Active Magnetic Bearing Control
Degree Master of Science (M.S.)
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Marcio S. de Queiroz Committee Chair
Kemin Zhou Committee Member
Yitshak M. Ram Committee Member
  • nonlinear backstepping control
  • robust control
Date of Defense 2003-04-02
Availability unrestricted
A solution to the problem of AMB control with reduced electrical power losses will be presented in this thesis. The proposed control solution will be founded on the integrator backstepping technique, which decouples the rotor stabilization problem from the bias flux design problem. It further allows for the easy redesign of the control law to compensate for uncertainties in the AMB system. A class of nonlinear controllers will be developed that reduces the AMB power losses in comparison to standard fixed-bias controllers, while containing no control singularity. Control laws will be presented for the standard AMB operating mode where both electromagnets are active at all times, as well as for the “energy-saving” operating mode where only a single electromagnet is active at any given time.

The main contribution of this work is the development of a smart bias flux, and function of the rotor position and velocity. General conditions motivated by physical and mathematical properties are developed for the functional form of the bias, ensuring the reduction of power losses and the avoidance control singularities without affecting the closed-loop system stability. Simulation results also illustrate the interesting role the smart bias plays in stabilizing the rotor. Note that while the power loss discussion in this thesis is focused on ohmic losses, the proposed control strategies also help reduce eddy current- and hysteresis-induced losses due to their proportionality to the magnetic flux.

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