High-Precision Permaent Magent Motor Design for Satellite Attitude Control with High Torque Density and Low Torque Ripple

This paper proposes a high-precision permanent magnet (PM) motor primary used for the small satellite attitude control. A radial-flux type motor is designed to achieve the high demanded smooth torque production for satellite applications. On the basis, a slotless stator is used to improve flux harmonics by removing the stator steel component. Several design methods are proposed to increase the torque output while minimizing the ripples under the slotless topology. First, leakage fluxes caused by slotless stator are reduced by designing the radial-flux distribution with dual rotors. In this structure, two rotors can be used respectively for flux transmitter and flux receiver to concentrate the flux linkage across air gap. Second, rotor magnets are designed with Halbach array for the sinusoidal magnet flux distribution. Halbach array results in more torque production at low ripples. In this paper, finite element analysis (FEA) is used as the simulation tool for the motor design. A prototype is fabricated for the experimental evaluation.