Permanent Magnets with Magnetizing Winding for Varying Mechanical Stiffness

Abstract

The paper considers passive magnetic bearings for small and medium-sized rotating rotors. It proposes several schemes of a magnetic support made using two permanent annular magnets with the axial magnetization. A distinctive feature of these magnetic bearing schemes is the possibility of short-term changes in the stiffness parameters. This is achieved through the use of bias windings. The technique and results of computational studies to determine the dependencies of the restoring magnetic forces and stiffnesses on the displacement of the rotor in the radial direction are presented. The validation of the calculation results was carried out according to the experimental data for an option of a controlled radial passive magnetic bearing used in a test rig. This rig implements a full rotor magnetic suspension, includes two radial passive magnetic bearings and one axial active magnetic bearing and is a prototype for small and medium-sized turbomachines. The paper also presents a comparative analysis of various design schemes of passive magnetic bearings with controlled stiffness.