Eddy-current power loss in toroidal cores with rectangular cross section

In this paper, we investigate eddy-current power loss in toroidal cores with a rectangular cross section. An analytical method is used in which the field variables are expressed in terms of products of Bessel functions and trigonometric functions. A closed-form expression is derived for the power loss. The influence of various parameters such as skin depth and core dimensions over a wide range is discussed. Simplified expressions for the power loss at special cases such as very small and very large skin depths are provided. A comparison with measured values is presented.