Motion control strategy and operational behaviour of a high-speed bearingless disc drive

In the last decade, bearingless drives have found their way into applications such as pumps for delicate media like blood or sensitive chemicals, as well as drives for bioreactors and chemical process chambers. With all these applications running at relatively low speeds below 15,000 rpm, the suitability of bearingless drives for high-speed operation remained unclear. This presentation gives a brief description of a high-speed bearingless disc drive which is designed to reach speeds beyond 100,000 rpm. Aside from special requirements such as rotor material strength and low stator loss characteristics, the control system also faces new tasks arising from the combined motor-bearing unit. Finally, the operational behaviour of the constructed prototype is presented, on the basis of the phase current amplitude and the resulting rotor orbit.