Bearing Selection of 20KW High Speed Motor and Analysis of Rotor Dynamic Characteristics

High speed motor has the advantages of small size and large power and is widely used in the industrial field. To design a motor for an air bearing performance test bed, the motor’s speed is required to be 50000 r/min, and the power is 20 kW. Bearing, as an important part of rotor system, which working performance and life will affect the reliability of the whole motor. Therefore, bearing must be selected reasonably according to the working load, working speed, etc. Which is a necessary condition to ensure the normal operation of the motor, so as to effectively improve the motor life. At the same time, the high running speed makes the motor more and more demanding on the rotor dynamic characteristics. In order to avoid the resonance caused by the coincidence of the rated speed and the natural frequency of the rotor, the dynamic characteristics of the rotor were analyzed by Ansys, and the modal shape of the rotor under the corresponding working state was obtained. [1] According to the analysis of Campbell diagram, the resonance frequency of the rotor is much higher than 50000 r/min. In order to reduce the design margin, the first six natural frequencies are calculated under different bearing steel stiffness, providing a reference for bearing stiffness selection.