The design of a centrifugal blower rotor with magnetic bearings based on rotor dynamics

摘要

A maglev centrifugal blower rotor with magnetic bearings is designed and developed by rotor dynamics. The shaft diameter is initially set according to the magnetic bearings and engineering experience, the finite element model calculation shows the first bending critical speed of the initially designed rotor without silicon steel sheets is closed to the rated speed. To avoid the resonance, the shaft diameter of magnetic bearings section increases and the length of left and right enameled wire section are reduced, thus the first bending critical speed increases, which and the second rigid critical speed have more than 15% margin to the rated speed within support stiffness of 10~5 N/m～10~7 N/m, the first bending critical speed of the revised rotor with silicon steel sheets increases a little compared to that without silicon steel sheets. At the condition of dynamic balance grade of G2.5 and the damping ratio of 0.707, the vibration amplitudes of the revised rotor are far less than the protective gap, the gyroscopic effect influences more and more with the increase of angular speed, so that the vibration amplitudes with different support stiffness tend to be the same, then the lower support stiffness such as 5×10~5 N/m can be chosen to facilitate the control system design.