It is essential for engineers to improve overall performance of electromagnetic devices. In this paper, single/multi-objective design optimization of double-sided permanent-magnet radial-flux eddy-current couplers is carried out. To this end, an analytical model of such devices is developed by combining conventional magnetic equivalent circuit techniques with Faraday's and Ampere's laws. The model is capable of easily dealing with complex geometries and material properties such as iron saturation and the PM characteristics as well as the associated design constraints so that the designs that are more realistic can be achieved. A genetic algorithm that enjoys a flexible objective function is finally adopted to find the optimal machine parameters. Finite-element method is also employed to verify the results. (C) 2013 Elsevier B.V. All rights reserved.