This novel magnetically levitated drive is of a unique type since it has no need for permanent magnetic material in the rotor. Hence it is cheap to manufacture, conserves ecological resources, is very robust and temperature resistant. The implemented homopolar motor topology was never applied in bearingless slice motors before and was comprehensively designed, optimized and implemented by LCM.

Magnetic bearing technology enables the completely contactless suspension of a rotating shaft, leading inherently to a number of advantages. This wear- and seal-less bearing is mainly used in applications that have extreme demands on cleanliness, lifetime and speed, as they normally occur in the semiconductor industry, in biomedicine, in heavy-duty machinery and in aerospace applications.

Bearingless slice motors combine the magnetic bearing and the electrical drive technology into one compact device, that fulfils both magnetic force and drive torque generation. In the state-of-the-art systems of this kind, the rotors have to be equipped with permanent magnets. Unfortunately this material features severe drawbacks. They are quite expensive and limit the temperature range for the application.

In cooperation with the Swiss Levitronix company, LCM has achieved to put the worldwide first bearingless slice motor without any permanent magnet material in the rotor into operation. For this reason a unique rotor, featuring salient poles, called reluctance rotor, was implemented. This rotor merely consists of simple ferromagnetic material. Various measurements have shown that the performance of the bearingless reluctance slice drive is comparable with standard slice drives concerning bearing force and torque density.

The high international standing and reputation of LCM in the scientific area of magnetic bearings is manifested in hosting the world’s most important biannual magnetic bearing conference, the ISMB14, in Linz. Under the patronage and organization of LCM more than 200 international researcher, developer and companies of the magnetic bearing community gathered together in Linz to discuss the latest developments and trends in this field

Impact and effects

By permanent magnet-free rotors manufacture gets much simpler and cost effective. Additionally, it leads to a very robust systems compared to bearingless state-of-the-art drives, that are especially very well suited for extreme temperature applications. Due to the fact that standard permanent magnets comprise of rare earth materials, which are of restricted availability and problematic to the environment, also a positive ecological impact is comprised in this development.

This project was carried out by the K2 are of LCM`s  together with the Institute of Electrical Drives and Power Electronics (Prof. Wolfgang Amrhein, Dr. Wolfgang Gruber) in collaboration with the Swiss Levitronix GmbH.

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