유체동압베어링이 적용된 통신중계기용 쿨링 팬모터의 회전자 부상에 따른 소음 저감 강건설계

Abstract

We identified the noise source of the cooling fan motor with fluid dynamic bearings in telecommunication repeater due to flying height. Flying height of rotor was determined by the equilibrium equation of weight, thrust force, and unbalanced magnetic force. Thrust force and unbalanced magnetic force were calculated by using computational fluid dynamics (CFD) analysis and electromagnetic analysis, respectively. Analyzed flying height was verified by measuring the flying height of a rotor due to various mounting angles. We proposed the robust design that can prevent flying motion by adjusting the axial relative position between permanent magnet and stator in such a way that unbalanced magnetic force suppresses propulsive force of a rotating fan. We measured the flying height and overall noise of conventional and proposed models and we observed that the proposed model had lower noise than the conventional model.