Optimization Framework for a Large, High Speed Bearingless Permanent Magnet Motor

Recently, there has been increased research interest in developing higher power bearingless motors. To reach significant power levels, rigorous design optimization is needed. This paper investigates the electromagnetic design space for a 30k r/min, 50kW bearingless permanent magnet motor. The differential evolution optimization algorithm is used to optimize two different design topologies for various objective functions. Detailed modeling considerations are presented to calculate the key performance metrics which are unique to bearingless motor designs (i.e., average and ripple suspension forces) in a computationally efficient manner. The resulting optimal design geometry is compared to demonstrate the wide design space of this machine. Finally, a weighted multi-objective function is proposed based on efficiency, force and torque ripple, and power density.