Abstract
This paper proposes a novel structure of a slotless single-drive bearingless motor, which is driven by only one three-phase inverter with one active suspension control in the axial direction. The motor consists of three-phase six square-shaped coreless coils as a stator for high speed applications, and a 4-pole surface-mounted permanent magnet (SPM) rotor. The rotor PMs are partly twisted by 90 degrees. The d-axis current, which is commonly used for magnetic field weakening or strengthening, generates the axial suspension force due to the Lorentz force on the end-windings of the coreless coils. The driving torque is generated with q-axis current. Hence, the proposed bearingless motor can generate axial suspension force and torque by only one three-phase inverter. The proposed structure, principle of suspension force and torque production, and calculation results are shown in this paper.
