20 Years Bearingless Slice Motor - its Developments and Applications

Bearingless slice motors are very compact and cost effective systems that allow full magnetic levitation in all degrees of freedom. Due to the disc shaped rotor, tilting and axial position are passively stabilized by the permanent magnetic biased air gap field, whereas the radial position and the rotor speed are actively controlled. This paper summarizes the continuous development in the field of bearingless slice motors ongoing for over 20 years. Different implemented topologies are outlined and basic characteristic values are compared. Such an extensive overview will help to show general trends, limits and capabilities of bearingless slice motors and their applicability in industry and academia.