Design of a Brushless Permanent-Magnet Synchronous Drive With a Purely Passively Suspended Rotor

This paper deals with the design and optimization of a permanent-magnet synchronous machine as a means of propulsion for a passively levitated rotation system. The strict conditions in terms of axial and radial stiffness and the limited construction space particularly affect the design process. Three-dimensional finite-element simulations were performed to obtain the most efficient drive that fulfills the constraints. Additionally, a passive magnetic bearing was designed, which is capable of compensating for gravitational and load forces in the axial direction and of stabilizing the rotor in the radial direction. The optimization process and the constructed prototype system are described, and the work concludes with measurements validating the accuracy of the simulations.