Transverse Flux Induction Heating And Its Optimization Problem

Transverse flux induction heating (TFIH) involving three-dimensional non-liner coupled problem of eddy current field and temperature field for continuously moving strip, which is highly challenging to researchers, has been a hot problem for Electrical Engineering, Materials Science and Engineering and Metallurgical Engineering cross-discipline research worldwide.Mathematical model is offered for solving the coupled problem for TFIH. To improve the efficiency of eddy current field calculation with A - formulation, necessary simplification is applied and boundary conditions are accurately analyzed. For the continuously moving strip, sets of stable and transient temperature equations are derived separately. The finite element method is applied in conjunction with the Galerkin method to three-dimensional, non-liner eddy current field and its coupled temperature field computation, the resulted eddy current, heat source and the final temperature distribution demonstrated and analyzed.Taking advantage of the continuity of strip moving, heat source moving method is presented, which instead of thin strip movement, the heat source in elements moves in the opposite direction for the coupled field analysis. In the stepping process of the strip, the heat source can be easily copied from one position to another, resulting in that successive temperature field computations could apply the same heat source distribution derived from a single eddy current field calculation in the whole procedure, and consequently, the time for numerical simulation of TFIH is greatly reduced.The relation between coil geometry and eddy current or temperature distribution is investigated theoretically and numerically. It is found that the eddy current distribution mainly concentrates on the projection of coil geometry on the strip surface, and to get a uniform temperature distribution along the strip width, the integrated projection areas along the moving direction should be equal. Additionally, the edge effect and other parameters also havesomewhat influence on the distribution. Considering these aspects, a suggestion is provided for coil design for TFIH equipments in order to produce a uniform temperature distribution at the outlet, which has been demonstrated by numerical calculation.With the results of three-dimensional finite element calculation as training examples, two neural networks are set up for predicting average temperature and its average relative error at the outlet of TFIH equipment, respectively. The results of tested examples show that the network predictions have high accuracy and could be used for the study of the effect of current and frequency on average temperature and its average relative error. Simulated annealing method was used to get the least average relative error for a given temperature.