Affiliations: [a] State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University, Xi’an, China | [b] School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an, China
Correspondence:
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Corresponding author: Haipeng Geng, State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University, Xi’an, China; and School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an, China. E-mail: genghaipeng@mail.xjtu.edu.cn
Abstract: Gas foil bearings (GFBs) are widely used in synchronous motors for their splendid performance in high speed. However, its working principle can produce unbalanced magnetic pull (UMP) between stator and rotor inevitably. Based on the rotor transverse vibration, this paper analysis the influence of UMP on the dynamic behavior of the rotor system supported by GFBs. The results show that the UMP accounts for a higher proportion of the exciting force acting on the rotor system at lower speed range. And the UMP declines with the decrease of nominal clearance. It is found that UMP will advance the critical speed of rotor system. According to the simulation results, the rated speed of synchronous motor is set at 90 000 rpm, and the nominal clearance of GFBs is 8 μm. The experimental results show that the rotor system designed in this paper works stably and achieves the predetermined design goal.
Keywords: Synchronous motor, unbalanced magnetic pull, gas foil bearings, critical speed, trajectory calculation
