Comparison of two techniques for the solution of the 3-D nonlinear transient eddy current problem

A comparison of two numerical methods, Crank-Nicolson and the state-space, is presented. These methods are associated with the solution of 3-D nonlinear eddy current problems using finite elements. Details of their formulations are outlined and compared. Both algorithms were applied to a sample problem which comprises thin steel plates with a narrow gap. This magnetic circuit was placed over a coil excited by a time-varying source. Comparisons of the results obtained from these methods with the values from laboratory measurements show that the presented methods are accurate. The computation time, however, is an advantage for the state-space method, with only 25% of that for the Crank-Nicolson algorithm