A new repulsive type magnetic bearing-modeling and control

This paper reports on the development of a new repulsive type magnetic bearing system whose radial bearing section makes good utilization of the repulsive forces between stator and rotor permanent magnets resulting in a simplified axial control scheme. The shape and configuration of the permanent magnet is the most critical component for satisfactory operation of this type of magnetic bearing. In this paper, modeling of the permanent magnets has been done with the help of finite element analysis and the nature of the repulsive forces and stiffnesses are estimated along the three directions. Using the forces and expressing the rotor dynamics the issue of modeling a real physical repulsive type magnetic bearing system is discussed. The controller has been configured around a digital signal processor. A prototype model has been designed and fabricated in our laboratory and experiments are carried out.