Computation of 3-D current driven eddy current problems using cutting surfaces

Since the traditional formulation in terms of a current vector potential T and a magnetic scalar potential ψ enforces zero net current in conductors, they cannot be used to solve current driven eddy current problems. For this reason, an alternative using T-T₀-ψ formulation where T₀ described an arbitrary current distribution with the given net current in conductors has been proposed some years ago. An alternative finite element T-H_j-φ formulation using cutting surfaces is proposed. A cutting surface describing the given net current in the conductor is introduced in the nonconducting multi-connected region in order to allow a discontinuity of the scalar potential. This method also avoids cancellation errors in permeable regions and ensures a good numerical stability of the finite element scheme. The present method is validated with a 3-D current driven eddy current problem. Results are compared to T-T₀-ψ formulation computation