Dynamic Characteristics of Flexible Rotor System of High Speed Motor with Magnetic Bearings

High speed motor with magnetic bearings has been developing due to its advantages of small size, high power density, no mechanical wear and low maintenance cost. In order to reduce vibrations, dynamic characteristics of the flexible rotor system of high speed motor for operation rotation speed 200000r/min with magnetic bearings are investigated. Results show that high speed motor may pass through some critical speeds and it is accurate to consider the motor shaft as a flexible rotor. Meanwhile, it is necessary to take measures to reduce the amplitude of resonance region of high speed motor such as increasing system damping. The critical speed increases with the increase of the bearing stiffness, which is a good way to remove the critical speed below working rotation speed.