Combined Winding Design for Improving Suspension Force Characteristics of Bearingless Motors

This article proposes a combined winding design technique for improving the suspension force capability of bearingless motors, especially those having two pole suspension magnetic field. The influence of magnetomotive force harmonics of both torque winding and suspension winding on suspension force ripple is analyzed, and an ensuing insight in selecting slot-pole combinations and coil pitch is discussed. Finite element analysis of the example consequent-pole permanent-magnet motor shows the design following our design guideline has higher suspension force amplitude and lower suspension force ripple.