10 Mrpm spinning ball motor: Preparing the next generation of ultra-high speed drive systems

This paper presents conceptual ideas for an ultra-high speed spinning ball motor with a target speed in the range of several tens of million rotations per minute. The research should prepare the next generation of ultrahigh speed motors. The focus of this work is to investigate physical limitations and discuss feasible concepts for the realization of such drive systems. One major issue is the analysis of the mechanical stresses occurring in the rotor during centrifugal rotation with focus on the rotor shape by using 3D FEM simulation tools. Furthermore, magnetic levitation concepts for a friction-less bearing system are presented and discussed. Two alternative concepts for the position sensing system, which is necessary for detecting the rotor position for the magnetic bearing, are presented and compared. Finally, a first motor prototype is presented to offer basic behavioral insights into the system and its stability.