Miniaturization and improvement of cogging torque characteristic for IPM type 5-DOF self-bearing motor

Abstract

5-DOF self-bearing motor possesses the functions of a motor, two radial active magnetic bearings (AMBs), and an axial AMB. It is possible to downsize the AMB system while still maintaining a high level of support performance. In a 5-DOF self-bearing motor, the IPM rotor generates bias fluxes in not only the radial direction but also in the axial and tilt directions without any side surface permanent magnets. However, cogging torques are inherently generates by the magnetic flux flow in a IPM rotor. The proposed flux recovery-type permanent magnets configuration was analyzed using the 3-dimensional finite element method. The results show a significant reduction of the cogging torques and an improvement to motor efficiency.