Conical magnetic bearings with radial and thrust control

Conical magnetic bearings with radial and thrust (axial) control are discussed. A model of the conical bearing is developed in state-variable form. Air-gap flux, air-gap displacement, and velocity are used as state variables. A control method based on recent developments in control theory, called Q-parameterization theory, is proposed and used to design a stabilizing controller for the system, which without control is unstable. The control parameters are chosen using CONSOLE (a software tandem for interactive optimization-based design), so that all design requirements are satisfied. Digital simulation was used to verify the method. Transient responses, forced response in all three directions (vertical, horizontal, and axial), and the interactions between them are discussed. Stiffness and whirling characteristics are obtained. The results are satisfactory and confirm the validity of the technique. A method is proposed for compensation of imbalance in magnetic bearings