Study on Hybrid Magnetic Bearing

研究了静压空气轴承与磁轴承组合的复合式磁轴承的动态特性。本研究提出的混合磁轴承主轴的基本参数为：轴直径；60mm最大速度；50000rpm （DN值=3,000,000）径向承载能力；1000n，径向刚度；100N/mum轴向承载能力；5000N，轴向刚度；首先，设计和制造了可避免描述的混合磁力主轴，然后对主轴的动态特性进行了研究。所得结果如下：主轴的承载能力和静刚度与期望值基本一致，实验中观察到静压轴承和磁浮轴承对主轴承载能力和刚度的多重影响。通过对系统动态刚度的测试表明，调整PID参数以获得最大的性能是非常重要的。在高速旋转测试中，在45,000rpm以上观察到轴的明显偏转。根据这一结果，对轴的强度和制造工艺进行了进一步的研究。对于高速旋转时的动态稳定性，PID控制得到的性能相对较低，并且存在轴高弯曲振动的溢出现象。这些结果表明了PID控制系统的局限性。然后利用DSP实现H *数字控制。采用较低阶滤波模型对其动态特性进行了仿真，结果表明该数字控制系统具有良好的动态特性，因此，该数字控制系统对于获得较高的混合磁主轴动态性能是非常有用的，值得进一步研究。10. 关键字

The dynamic characteristics of hybrid magnetic bearing that is combined by the hydrostatic air bearings and magnetic bearings is investigated. Basic specification of the spindle with the hybrid magnetic bearing proposed in this study is as follows : Diameter of the shaft ; 60mm Maximum speed ; 50000rpm (DN value=3,000,000) Radial load carrying capacity ; 1000n, Radial stiffness ; 100N/mum Axial load carrying capacity ; 5000N,Axial stiffness ; 500N/mumFirst of all, avobe described hybrid magnetic spindle is designed and manufactured and then the dynamic characteristics of the spindle is investigated. The reults obtained are follows. The load carrying capacity and static stiffness of the spindle are almost same values with the expected values and the multiple effect of the hydrostatic and magnetic bearings on the loard carrying capacity and stiffness of the spindle are observed in the experiment. It is declared from the tests of dynmic stiffnes of the system that tuning the PID parameters to obtain the maximum performance is very important. At high speed rotating tests, a significant deflection of the shaft is observed over 45,000rpm. From this result, the strength and manufacturing process of the shaft are rested to be more investigated. With respet to the dynamic stability at high speed rotation, relatively lower performance is obtained by the PID controll and also the spill-over phenomena of the higher bending vibration of the shaft is observed. These results sugest the limitation of the PID control system. Then H * digital control with DSP is applied to the system. The simulation of dynami characteristics with relatively lower order filtering model shows the good charcteristics, therefore, the digital control system is very usefull to obtain the higher dyanamic performance of the hybrid magnetic spindle and it has to be more investigated in future. 10. Key words