Structure, Design and Verification of Axial Flux Bearingless Hysteresis Motor

Bearingless motors can be used in special applications such as blood pumps due to the elimination of mechanical wear, and the hysteresis motor has the advantages of reliability and cleanliness due to its solid rotor. In this paper, a novel axial flux bearingless hysteresis motor is proposed, whose rotor is located between the upper and lower stators, and is actively controlled in rotation, axial and tilting motion. It has good stability and a large output torque to meet the needs of blood pump applications. The electromagnetic principle, winding configuration and analytical model are explained in this paper. The theoretical derivation shows that the axial force does not change with the torque current phase angle, and the tilt torque is uniform in different tilting directions. Then the finite element model is built and the results further reveal the effects of current amplitude and airgap length on hysteresis torque, axial force and tilt torque. Finally, the experimental tests are carried out in synchronized operation. When the rotor impeller is stably operated at 1000 rpm in a mixture of water and glycerin, the output torque is measured to be about 35 mN · m.