Analysis and design of an ultra-high-speed slotless self-bearing permanent-magnet motor

Active magnetic bearings (AMB) enable contactless operation and can therefore be used for supporting rotors spinning at high speeds. However, the rotational speed in conventional reluctance-force-based AMB topologies is limited which is mainly due to high rotor losses and achievable force control bandwidths. In this paper, a prototype of a self-bearing motor designed for rotational speeds of up to 500 000 revolutions per minute (rpm) is presented. Due to the employed AMB, the motor can be operated in high-purity or vacuum environments. An analytical mechanical and electrical bearing model is introduced and verified by measurements. Furthermore, a bearing inverter system is designed and its controller performance is shown. Closed-loop system measurements of a spinning levitated rotor at 400 000 rpm verify the functionality of the overall system. To the authors knowledge, this is the world record speed for magnetically-levitated electrical drive systems.

[1]  C. Zwyssig,et al.  Analysis and Measurement of Three-Dimensional Torque and Forces for Slotless Permanent-Magnet Motors , 2012, IEEE Transactions on Industry Applications.

[2]  J.W. Kolar,et al.  Novel high-speed, Lorentz-type, slotless self-bearing motor , 2010, 2010 IEEE Energy Conversion Congress and Exposition.

[3]  Christof Zwyssig.  An ultra-high-speed electrical drive system , 2008 .

[4]  Jesse W. Beams,et al.  The Production of High Centrifugal Fields , 1946 .

[5]  Philipp Imoberdorf.  Ultrakompakter Antrieb mit radial und axial kombiniertem Magnetlager , 2011 .

[6]  T. Grochmal,et al.  Control of a self-bearing servomotor , 2009, IEEE Control Systems.

[7]  J.W. Kolar,et al.  Megaspeed Drive Systems: Pushing Beyond 1 Million r/min , 2009, IEEE/ASME Transactions on Mechatronics.

[8]  Jan Abraham Ferreira,et al.  On the Speed Limits of Permanent-Magnet Machines , 2010, IEEE Transactions on Industrial Electronics.

[9]  Zhaohui Ren,et al.  Force characteristics and gain determination for a slotless self-bearing motor , 2006, IEEE Transactions on Magnetics.

[10]  F. Betschon.  Design principles of integrated magnetic bearings , 2000 .

[11]  Seung-Ki Sul,et al.  Analysis and design of a decoupling current controller for AC machines: a unified transfer-matrix approach , 2005, Fourtieth IAS Annual Meeting. Conference Record of the 2005 Industry Applications Conference, 2005..

[12]  J. Kolar,et al.  Efficiency Optimization of a 100-W 500 000-r/min Permanent-Magnet Machine Including Air-Friction Losses , 2007, IEEE Transactions on Industry Applications.

[13]  H. Mitterhofer,et al.  Design aspects and test results of a high speed bearingless drive , 2011, 2011 IEEE Ninth International Conference on Power Electronics and Drive Systems.

[14]  J. Kolar,et al.  Analysis and measurement of 3D torque and forces for permanent magnet motors with slotless windings , 2010, 2010 IEEE Energy Conversion Congress and Exposition.

[15]  R. H. Munnig Schmidt,et al.  A miniature milling spindle with Active Magnetic Bearings , 2010 .

[16]  K. Sridhar.  Electromagnetic models for slotless PM synchronous motor drives , 1995, Proceedings of 1995 IEEE Applied Power Electronics Conference and Exposition - APEC'95.

[17]  Johann W. Kolar,et al.  PEEC-Based Numerical Optimization of Compact Radial Position Sensors for Active Magnetic Bearings , 2008 .

[18]  B. E. Kane.  Levitated spinning graphene flakes in an electric quadrupole ion trap , 2010, 1006.3774.

[19]  Johann W. Kolar,et al.  An Ultrahigh-Speed, Low Power Electrical Drive System , 2008, IEEE Transactions on Industrial Electronics.

[20]  Seong-yeol Yoo,et al.  Toroidally-Wound Self-Bearing BLDC Motor With Lorentz Force , 2010, IEEE Transactions on Magnetics.