The Study Of The Moving Conductor Eddy Current Problems By The Finite Element Method

This project is on the support of the Natural Science Foundation of Tianjin City. As you know, an electromagnetic field coupled problem containing a moving conductor is very popular in designing elecironiagnetic equipment This problem is solved in vast area, complicated on construction, related to ~vide range. In it, the numerical calculation of eddy current problem in moving electromagnetic system is the foundation of the application of magnetic technology. And it is also one of the hot-spot topics in the circles researching electromagnetic field. Some theories and numerical algorithms about the eddy current problem in moving electromagnetic system are studied in this paper. Through the analyses of the reasons causing distortional oscillation of the solution calculated with the method of finite elements, it is found that the existence of moving term causes the lack of diagonal dominance in the coefficient matrix of finite elements equation while destroying its symmetry. That leads to coefficient matrix of finite element equation become worse to solve, sets off that the numerical solution oscillates distortedly. To solve the issue, up- winding auto-adaptive iteration scheme is used in the solution of coefficient matrix to remedy the weakening from the moving tenTh improve the efficiency and accelerate the convergence speed of BI-CGSTAB, drop down the equivalent Peclet number and clear up the distortion oscillation efficiently. Using the storing technology of non-zero elements, this paper pt~sents a storage technique to reduce the occupied memory while solving a large spare non-symmetric matrix for finite element equation. An improved pre-condition matrix is applied to BI-CGSTAB algorithm to drop down the number of matrix condition, reduce the iterative times calculating the matrix and quicken the convergence speed. Having analyzed the finite element equations for eddy current problems in the moving coordinate system, this paper puts forward a way to modify the auto-adaptive eddy current term. It is certified that this method is efficient to get better accuracy and convergence by calculating some examples. In order to popularize the analysis in moving coordinate, three kind of schemes are given in this paper. They can be chosen according to moving speeds and the moving styles of the conductors. The software is programmed and verified through calculating TEAM Workshop a problem 9. All results prove that the theories, models, algorithms and programs are correct.