CONICAL MAGNETIC BEARINGS WITH RADIAL AND THRUST CONTROL

Conical magnetic bearings with radial and thrust (axial) control are discussed. First a model of the conical bearing is made in state variable form. Airgap flux, airgap displacement, and velocity are used as state variables. A new control method is proposed, based on recent developments in control theory. The method is called Q-parameterization theory and is used to design a stabilizing controller for the system which, without control, is unstable in nature. The controller parameters are chosen using console (a software tandem for interactive optimization-based design developed at the University of Maryland in 1987) so that all design requirements are satisfied. Digital simulation was used to verify the proposed control method. Transient responses, forced responses in all three directions (vertical, horizontal, and axial), and the interactions between them are discussed. Also, stiffness and whirling characteristics are obtained. The results obtained are satisfactory and suggest the robustness of the proposed technique.