Calculation of eddy current losses in air coils by finite element method

Calculations of eddy-current losses in air coils by Finite Element Method are described. For simplification the geometry of the problem is considered to be axisymmetric neglecting the pitch of turns. Therefore, each turn represents a separate conductor and the resulting multiconductor system is treated by the superposition principle. Since the number of calculations is directly related to the number of turns the solution becomes very time consuming even for large computers. To improve efficiency of the method a modified Frontal Solution algorithm has been developed providing the possibility of multiple solutions add, in addition, advantage was taken of the symmetry of the admittance coefficient matrix of the multiconductor system. For accuracy reasons quadratic and cubic isoparametric elements are used. For two reactors the eddy current behaviour was investigated and losses were calculated. The numerical results show excellent agreement with results obtained experimentally.