Study Of 3D Transient Electromagnetic Fields-Circuit-Moving System Coupled Problem

The coupled transient electromagnetic problems containing moving conductors is a complicated issue in the production of modern industry. The study of such problems is a hot-spot topic and difficult point for the computation of electromagnetic field in electrical engineering nowadays. The existing theoretical analysis methods need to be improved because of their unsatisfactory computational precision and too long computation time. Besides, developing a special software which is multifunctional and can analyses complex electromagnetic field problems on the base of a high level of theoretical analysis is very important for the optimal design and performance analysis of some electromechanical devices. Therefore, in this paper the author focuses on the following studies.Firstly, for theoretical analysis, the paper carried out the following work.1. The analysis of 3D transient eddy current field problems including nonlinear material characteristics is one of the paper's emphasis. The author applied the penalty function method to incorporate the zero divergence condition to the electromagnetic field governing equation, and this improved the satisfaction of zero divergence of nodal potential function at the condition of discretization. Through searching the value of penalty factor and its choosing method, the improvement for the analysis of 3D transient eddy current field problem has been realized.2. A 3D electromagnetic field-circuit directly coupled method which use flux linkage as the coupling unit is presented. The method can calculate the nodal magnetic potential functions and the branch current simultaneously. Besides, it can remain the symmetrical and sparse characteristics of equation coefficient matrix.3. The solving of the 3D moving electromagnetic problem is another emphasis of this paper. Firstly, the treatment of the moving boundary condition is very important. In order to increase the efficiency of pre-processing and remain the symmetrical and sparse characteristics of the coefficient matrix of FE discretized equations, the interpolation movement interface method is extended to 3D theoretically and applied to analyze a 3D transient moving electromagnetic problem in this paper. Secondly, the electromagnetic field and moving system coupled mathematic model was derived, in which the adjusting time step method is applied to simplify the iteration of the two system equations.4. A new method to analyze the 3D transient electromagnetic field-circuit -movement coupled problem is presented. With this method the following factors can be included, such as how to increase efficiency and remain the symmetrical and sparse characteristics of coefficient matrix of FE discretized equations in the process of solving nonlinear material characteristics, electric circuit and movement problems. Therefore it can increase the accuracy of analyzing the 3D transient moving electromagnetic field problems and decrease the calculating time obviously.Secondly, based on the theoretical analysis, the Fortran program is created and applied to the analysis of a 3D moving electromagnetic field problem. The software can analyze the 3D transient eddy field and the electromagnetic field coupling with circuit and movement system problems commendably.Lastly, designed and product a experimental model to verify the analytical method of 3D transient eddy field problem which effect by circuit and movement system factors. A test macro with good accuracy was developed also. The calculated and test results are equal approximately, which proved the correctness of the theory and the validity of the software this paper presented.