Radial-Flux Permanent-Magnet Limited-Angle Torque Motors

Abstract

Slotless radial-flux permanent-magnet limited-angle torque motor with disturbed armature winding is analyzed in this paper. For the first time, the outer rotor structure is investigated for this type of the rotary actuator. The exact 2-D analytical modeling is applied to obtain the magnetic field parameters of the windings and excitation for both the outer rotor and the conventional inner rotor topologies. Also, the governing and geometrical equations are derived based on the analysis outcomes. Then, they are validated by applying the finite-elements tool. Both topologies are designed and compared with each other considering a variety of utilization parameters of these actuators. Avoiding saturation is considered as a designing criterion, which corresponds to the maximum torque production without distortion of linear characteristics in short-time operations. Experimental results show good accuracy of the theoretical design and numerical simulations. Comparison of the results shows significantly better performance of the new proposed actuator with the outer rotor structure against the conventional inner rotor type.