Research On The Electromagnet And Permanent Magnet Suspension Spinning Cup

The research object of this paper is spinning cup that using active magnetic bearing in the radialdirection and permanent magnetic bearing (PMB) in the axial direction. Firstly, the spinning cup’sworking principle and the bearing structure are introduced briefly. Then the strength of silicon steeland permanent magnet is analysed based on thick cylinder theory and simulated using ANSYS, theresults show that it meets the strength demand although the rotating speed is very high, because therotor diameter is relatively small. After that, the axial PMB is analysed, including numericalcalculation based on equivalent magnetic charge method and2-D electromagnetic field analysis, alsothe effect of magnet parameters on bearing performance is discussed, the characteristic curveillustrating the law that force changes with the displacement is obtained. In aspect of rotor dynamics,critical speed and vibration modes are calculated and the relationship between critical speed and thebearing stiffness is analyzed, the conclusion provides a theoretical basis for the design of magneticbearing. Finally, experiments about the spinning cup are carried out, including static suspensionexperiment、bearing characteristics experiment、experimental modal analysis and the high-speedrotating experiment. According to the experiment results, the maximum carrying capacity of spinningcup is10N in the axial direction and78N in the radial direction, the axial stiffness achieves maximumat the equilibrium position, the value is about6000N/m; the working rotating speed locates betweenthe second and the third critical speed, and has enough distance from the critical speed. In thehigh-speed rotating experiment, the coil current and the displacement signal are detected, which showthat the rotor’s vibration enhances obviously around the critical speed, but the rotor didn’t collide withthe stator when rotating.