Modeling and control of an integrated axial passive and radial active magnetic bearing system

In order to reduce power losses of magnetic bearings in a magnetically suspended control moment gyro (MSCMG), this paper reports the development of a magnetic bearing system that integrates axial repulsive passive magnetic bearing and radial active magnetic bearing. In this paper, modeling of the permanent magnetic for the Halbach structure has been done with the help of magnetic charge method. The repulsive forces and stiffness are estimated. The bearing stiffness varies strongly with the displacement from the modeling expressions. Robust PID controller is designed for radial active magnetic bearings to ensure the stability of the rotor suspension. A prototype has been designed and fabricated. The experimental results show that the estimated repulsive forces and stiffness are consistent with the theoretical analysis.