Critical speed calculation and mode analysis of rotor for high speed motor

A 3D finite element analysis(FEA) is used to establish the critical speed and vibration mode of the magnetic bearing-rotor system of high-speed motor.Also,the bearing stiffness of 3D-FEA model was determined using vibration experiment according to the suspension characteristics of the magnetic bearing system.The critical speeds calculated using FEA are consistent with actual results of the rotor system.The study shows that the bearing stiffness has significant impact on the critical speed of rotor.The critical speed can be adjusted by changing bearing stiffness and material properties.The shaft extension should be maintained at a safe range in order to avoid critical speed at rotor bending modes.