Stiffness and critical speed calculation of magnetic bearing-rotor system based on FEA

The 3D finite element analysis (FEA) is used to establish the natural frequencies and vibration modes of the magnetic bearing-rotor system of high-speed machine and to define bearing stiffness of 3D-FEA model by exciting experiment. The critical speeds calculated by the method of FEA consistent with tested results of a high speed permanent magnet (PM). The study shows that the magnetic bearings introduce three new vibration modes with low frequencies which are often within the operating speed range of high-speed machine.