On the High Speed Capacity of Bearingless Drives

With soaring raw material costs, the need for smaller drives running at higher speeds is ever increasing. In parallel, magnetic bearings and bearingless drives have outgrown the purely academic level and are the state of the art solution for several industrial processes. All the bearingless drives in industry and most of them in academic research run at relatively low speeds of up to 15 000 r/min. Thus, the suitability for high speed operation remained unclear. Along with a brief introduction to bearingless drives, the criteria for high speed operation and the ability of this topology to fulfill them is discussed in the first part. The second part gives a description of a prototype system, designed to reach speeds of beyond 100 000 r/min. The last section shows the experimental results of the prototype concerning the operational behavior.