On the limits of validity of the impedance boundary conditions for the analysis of induced currents in solid conductors

The analysis of induced currents in conducting bodies due to the presence of an external magnetic field variable with time is necessary in numerous areas of applied electromagnetics, such as induction heating, eddy-current braking, electromagnetic shielding and electromagnetic levitation. An accurate study of the induced currents requires the field solution for both the inside and outside of the conductor. Exact analytical solutions are possible for a limited number of geometries. In order to reduce substantially the amount of computation, at high frequencies one can use the impedance boundary condition (IBC) models where only the field solution outside the conductor is needed. The simplest model is the perfect electrical conductor (PEC) model. More accurate results can be obtained by using the standard impedance boundary condition (SIBC) model and also the curvature corrected surface impedance models.