The calculation of transient eddy-current fields using null-field integral techniques

The transient eddy-current problem is characteristically computationally intensive. The motivation for this research was to realize an efficient accurate solution technique involving small matrices via an eigenvalue approach. Such a technique is indeed realized and tested using the null-field integral technique. Using smart (i.e., efficient, global) basis functions to represent unknowns in terms of a minimum number of unknowns, homogeneous eigenvectors and eigenvalues are first determined. The general excitatory response is then represented in terms of these eigenvalues and eigenvectors. Excellent results are obtained for the Argonne FELIX cylinder experiments using a 4 × 4 matrix. Extension to the three-dimensional problem (short cylinder) is set-up in terms of an 8 × 8 matrix.