Diagnosis And Mechanism Research On Noise Source For Magnetic Suspended Rotor

Magnetic suspended rotor is an electromechanical integral product of multidisciplinary intersection technique, which consists of mechanism, electromagnetic, control system and sensing transmitters. Until by now, there is neither a set of mature noise and vibration measurement method, nor carrying on any related experiment to verify it when magnetic suspended rotor is running.In this paper, this is made sound characteristics generalization about the researched rotor at first, and then classified its sound according to the sound characteristics and mechanism. The sound intensity measurement is applied to which is insensitive to background noise. In which, it introduces the phonometry fundamentals, errors kind, merits and drawbacks when using phonometry, and the most important predominance is that it doesn't need special anechoic chamber or random diffusion chamber. Second, it discusses some remarkable problems here: rotor assumption on sound intensity testing model;sound intensity testing under strong background noise field, air-stream noise under high-speed revolution.Connecting the magnetic suspended rotor structure, its noise source has been divided to three parts: electromagnetic noise in magnetic bearings which caused by the silicon-steel sheets magnetostriction;asynchronous motor noise which including aerodynamic noise, mechanical noise and electromagnetic noise, electromagnetic noise is obvious in low-frequency that mainly caused by the basic frequency of radial force fluctuation in motor stator magnetic field harmonic wave, unilateral magnetic force and working harmonic wave with order numbers of motor rotor pole-pairs;rotor and catching bearings noise which including rotor rotational noise, force transmission impact noise between rotor and catching bearings, it discusses catching bearings noise detailedly when magnetic suspended rotor suspension and turning, doesn't involve rotor raising speed or reducing speed. In that process, the catching bearings inherent noise, noise relate to manufacture, noise after assembling and improper using noise all have been discussed.In experiment, it builds a test model for magnetic suspended rotor and does sound intensity measurement separately at different locations when the magneticsuspended rotor suspension only and suspension and turning, finally, the radiation power of sound source distribution maps are acquired. The main sound source locations are found out along the rotor reference axis of rotation according to testing results. At the same time, the rotor vibration signals are picked in suspension only. The sound frequencies are analyzed, referenced the rotor temperature field pictures of infrared camera, finally, the potential frequencies are brought forward.In order to find out distribute of magnetic suspended rotor noise frequency further, the main rotor sound sources: magnetic bearings, asynchronous motor and catching bearings, which mechanism and transfer path are discussed and analyzed deep and systematically on the base of detachment. In this paper, some frequencies which have notable contribution to magnetic suspended rotor are calculated. These consequences provide certain stands and guide for magnetic suspended rotor theoretical study and practical application, at the same time, these also guide its design and manufacture.