Analytical models play an important role in the design of electromagnetic devices by providing computationally efficient solutions. In this paper, by combining magnetic equivalent circuit approaches and Faraday's and Ampere's laws, a model for radial-flux eddy-current couplers is developed, which can easily handle complex geometries as well as account for iron saturation, all material properties, and three-dimensional (3-D) parameters. The characteristics and the design considerations of a surface-mounted permanent-magnet structure are presented. Also, a procedure aimed at an optimal design of the yoke thicknesses is utilized. Moreover, 2-D and 3-D finite-element methods are employed in the analyses and evaluation of the model. Finally, sensitivity analysis is performed to explore the impacts of the machine parameters on the device performance.