Experimental Electromechanical Characterization of Slotted and Slotless Miniature Bearingless Drives

Magnetically-levitated drives are interesting in applications which demand a combination of reliable operation and high speeds. In the latter domain, slotless stators are recognized as the most suitable, as they deliver higher power density and lower speed-dependent losses. Nevertheless, the larger airgaps proper to slotless topologies minder bearing load capacities. In this study, a slotless and slotted drive designed for the same rotor are experimentally characterized. They are compared head-to-head in terms of passive stiffnesses and torque and force generation. A bearing control effort factor is also defined.