Effects of rotor pole angle on torque characteristics of a limited-angle torque motor

This paper presents a reluctance-type limited-angle torque motor (LATM), which is used for actuator or arming device in the aerospace industry, and its electromagnetic (EM) characteristics were examined with respect to changes in the rotor pole angle and the rotational position of the LATM. Among the various shape design parameters of the LATM, changes in the rotor pole angle theoretically influence the cross-sectional area of the air-gap, thereby influencing torque generation. A three-dimensional EM finite-element analysis (FEA) was used to evaluate the irregular distribution of the magnetic flux inside the LATM. Finally, an LATM model having a pole angle at which the average and maximum torque become the largest and the torque ripple becomes the smallest (20% or lower) was designed.