Analysis and Design of a Bearingless Axial-Force/Torque Motor with Flex-PCB Windings

The axial force/torque motor (AFTM) can generate axial bearing strength and drive torque simultaneously with a conventional 2-phase winding system. Since the end windings provide the active axial suspension forces, there is no necessity of additional windings to control the axial position. Passive magnetic ring bearings stabilize the remaining four degrees of freedom. It is crucial to achieving a high fabrication precision and filling factor of the winding to reach a high efficient AFTM. Therefore, we utilize the technique of directly printing the winding on a flexible printed circuit board (flex-PCB). The focus of this paper lies in the underlying design of the AFTM and the configuration of the flex-PCB windings. Analytic models that describe the influence of the motor dimensions on its force and torque generation capability are presented and validated by finite element method (FEM) analysis. Based on these results, a detailed experimental setup was designed to achieve performance validation.