Torque Performance Improvement of a Radial-Flux Slotted Limited-Angle Torque Motor by Tapered Tooth-Tip

Magnetic saturation problems and cogging torque normally result in a weak torque performance of conventional slotted limited-angle torque motors (LATMs). This paper presents a novel radial-flux slotted LATM with a tapered tooth-tip to improve the torque performance including average output torque and angular operation range. Firstly, the topology of tapered tooth-tip is analyzed and illustrated. Then, finite-element analysis is employed to compare the proposed LATM with the conventional slotted LATM. The comparisons of two topologies are concentrated in the air-gap flux density, cogging torque, back EMF, and output torque. Moreover, the influence of armature reaction on output torque is investigated. Finally, both conventional and proposed slotted LATMs are designed and prototyped. Torque characteristic experiments are carried out to confirm the torque capacity improvement of the proposed slotted LATM. Related experiment results are presented and discussed.