Modeling and iron-effect analysis on magnetic field and torque output of electromagnetic spherical actuators with iron stator

This paper presents a three-degree-of-freedom permanent magnet (PM) spherical actuator with an iron stator. The major contribution of this paper is to study the effect of iron stator on the magnetic field and torque output of the electromagnetic spherical actuator quantitatively and qualitatively. It could be helpful for actuator design optimization. Based on the poles' arrangement and the iron boundary, the magnetic field of the PM-pole rotor and the actuator torque are formulated analytically. The effect of iron stator on the magnetic field and torque output is analyzed with respect to structural parameters. The result shows that the iron stator can increase the radial component of the flux density and thus the actuator torque output significantly