Numerical Modeling for Induced Eddy Current Calculation on a Non-uniform Mesh

The eddy current is one of the unavoidable effects in the electrically conductive parts of electrical machines. Its calculation is not easily achieved. In particular, the induced current developed by the primary eddy current is generated, and it increases the computational complexity. In order to study the induced eddy current, this paper uses the finite difference method (FDM) as the numerical method, and the finite-difference (FD) stencil is applied to the curl, div., and the discrete Laplace operator. In addition, this paper applies some methods to reduce the numerical error the calculation. There are two general numerical errors: round-off errors by rounding of decimal values, and truncation error by using approximations in the mathematical process. Each error can be reduced by applying a higher order FD scheme, and a smaller increment of the local discretisation in the structure. Especially, to evaluate the eddy currents at the edges of the structure, the non-uniform mesh is proposed, which leads to a reduction of the computing costs as well. The numerical results gained with a non-uniform mesh is compared to the results reached by a commercial FEM tool to demonstrate the accuracy of the proposed method.