Comparison of high speed bearingless drive topologies with combined windings

For high speed bearingless disk drives, certain topologies are advantageous. The authors have published works on a bearingless disk drive for high speeds which is characterized by a slotless stator and a toroid winding set. Several different variations of this setup are imaginable. The ones which this work focuses on are the variation of the number of phases, of the number of coils, and of the applied coil connection. A comparison of the constructed and tested setup with the possible variations is presented in the course of this work.