FEM analysis of 3-D transformer leakage field and eddy current loss in the windings

The authors present a method which resolves the three-dimensional eddy current field into a 3-D time harmonic field external to the windings and n axisymmetric eddy current fields near the coils as an approximation for engineering applications. Because the isoparametric FEM (finite element method) with 3-D vector potential, is used in the time harmonic field analysis whereas, in the n axisymmetric eddy current field analysis, B-spline FEM is used, the method presented can give a solution with an accuracy quite acceptable for engineering purposes. The distributions of leakage fields, eddy current losses, and heat source in the windings obtained are compared with the test results. >