Suspension Force Design Guidelines for Bearingless Permanent Magnet Machines

Bearingless motors are electric machines capable of simultaneously creating both torque and suspension forces. Optimization algorithms are generally required to fully realize the performance capabilities of these machines due to trade-offs between force and torque performance. This paper focuses on developing design guidelines which can be used prior to employing an optimization algorithm to streamline the bearingless machine design process. As part of this effort, analytic tools are developed to evaluate the suspension performance of bearingless machines. To validate the model, observations made with the aid of the equations are cross-verified against FEA and optimization results. The paper goes on to show that by employing the proposed tools, engineers can gain physical insight into bearingless machine design and identify topologies best suited for their application early in the design process.