Performance Comparison of Bearingless Motor Topologies in Exterior Rotor Construction

This paper presents several feasible slot/pole combinations for a bearingless motor in exterior rotor construction. Due to the limited available stator space, the slot number of the stator has to be chosen small in order to provide sufficient winding space. The characteristics of each possible topology are discussed in great detail and for each setup the optimal design parameters are derived using 3D-FEM analysis. In the end, a fair comparison between the presented topologies is undertaken and the optimal motor topology is implemented in a real-size prototype setup.