Surface elements for modelling eddy currents in high permeability materials

A method for solving problems involving eddy currents flowing in thin surface layers in magnetically nonlinear iron is described. It is shown how an extension of the method of D. Rodger and N. Atkinson (1988) for modeling eddy currents in thin sheets can be used to model low skin depth problems using sheet elements which cover the surface of the eddy current regions. The resulting equations can be nonlinear if the permeability is dependent on fields. The volume of the iron need not be modeled using this method. Only the fundamental harmonic of the AC supply is considered and hysteresis effects are ignored. Nevertheless, the method has been shown to be useful in situations where a full volume, nonlinear transient solution would be computationally too expensive. Some experimental results are compared with simulations from the MEGA program package