AN EDDY CURRENT CONSTRAlNT FORMULATION FOR 30 ELECTROMAGNETIC FIELD CALCULATIONS

The use of Coulomb's gauge is sufficient for a unique solution in 30 magnetostatic field calculations in terms of the magnetic vector potential A. For the sinusoidal steady-state eddy current problem Coulomb's gauge is not sufficient. The combination of Coulombs gauge and an eddy current constraint provides a simple way of guaranteeing uniqueness. A formulation for 3D electromagnetic fields utilizing this constraint is proposed. Results comparing the present formulation with other finite element formulations and with experimental data are given. electromagnetic fields. The magnetic vector potential and the electric scalar potential are used as variables and the solution is rendered unique by use of the coulomb gauge together with a constraint equation on the eddy currents, based on the continuity equation. The formulation is compared with other commonly used formulations, showing more accurate results. The implementation of the method with 8 node hexahedral, isoparametric finite elements is given here. Results are presented for a heating problem where losses in a conductor are calculated and for an eddy current nondestructive testing problem. In the later, the induced voltage in a sensing coil is calculated. These results show good agreement with experimental data.