The toroidal electromagnetic coupler has many advantages over the classical transformer. It is widely used in low-power applications. However, there are some limits that hamper its use in modern and high-power applications, such as the cost, the difficulty of winding and, especially, the limited number of studies carried out on the thermal aspect. In this article, we look at the problem of cooling a high-power and very compact toroidal electromagnetic coupler used in smart grid systems. The cooling is modeled thanks to heat transfer coefficients considering the windings as a surface heat source. A mathematical model which is quick and useful for a first approach is developed, and the results obtained show the temperature distribution for convective boundary conditions inside and outside the hollow torus. In addition, a parametric study is carried out. It aims to determine the optimal internal and external convective heat transfer coefficients for which the temperature of the coupler remains below the material’s destruction threshold. Additionally, a 3D numerical model taking into account the wires of the toroidal coupler is studied and compared with the mathematical model. The good consistency between the two methods ensures that this simplified thermal modeling can be trusted for the study of thermal management during the design of future electromagnetic couplers.