Rethinking the Design of Non-Salient Bearingless Permanent Magnet Machines

Bearingless motors are electric machines capable of simultaneously creating both torque and suspension forces. A detailed investigation into the underlying physics governing magnetic force creation in these machines is conducted in this paper, resulting in a newly derived analytic bearingless machine force model. Several key insights on designing bearingless machines for optimum force and torque performance are obtained from this investigation, including designing bearingless machines to be compatible with field-weakening and with conductive rotors. Validation for these findings is provided numerically, using optimization and FEA, and experimentally with hardware test results as well. The analytical foundations of bearingless machine operation developed in this paper makes bearingless machine design more intuitive and will pave the way for further innovation in this burgeoning field.