Integral Design and Analysis of Passive Magnetic Bearing and Active Radial Magnetic Bearing for Agile Satellite Application

In this paper, the design and development of a magnetic bearing system which consists of passive magnetic axial/tilting bearing and active two-axial radial magnetic bearing (RMB) used in magnetically suspended wheel (MSW) or magnetically suspended control moment gyroscope (MSCMG) for agile satellite application is presented. The passive axial/tilting magnetic bearing supplies an axial position stiffness to stabilize the rotor in the axial direction and a tilting stiffness to restrain the rotor when subjected to gyroscopic torque. The active two-axis radial magnetic bearing with bias permanent magnet stabilizes the rotor on the axes perpendicular to the rotation axis. Considering the complex distribution of flux density the system performance cannot be accurately analyzed by the conventional magnetic circuit method because of the high coupling between force and moment produced by the axial magnetic axial/tilting bearing and RMB. To analyze the coupling problem of the force, moment, position stiffness, and tilting stiffness between the passive magnetic axial/tilting bearing and RMB, an integral design and analysis method based on three-dimensional finite-element method is presented. An example is given and analysis results prove that the high coupling occurs on the radial direction and the light occurs on the axial and tilting directions orthogonal to the spin axis. Then the linearized model is given in this paper.