A C . A . E . Package For an Intuitive Approach

1. Abstract We present in this paper a Computer Aided Education Package allowing to visualize the magnetic eld in and around the magnetic circuit of a double-U shaped contactor. The objective of this application is to allow students to intuitively understand the distribution of the magnetic eld when varying geometrical, electrical and magnetic parameters. The modeling of this problem is performed by solving in real time a non-linear nite element problem. The implementation of this method is greatly optimized in order to allow animating eld patterns in real time, in reaction to any user interaction. 2. Introduction We have already presented the Colos project in previous papers 1, 2, 4]. It is composed of research teams of ten universities located in seven diierent countries. Its major goal is to encourage the development of teaching methods so as to improve the knowledge and understanding of basic concepts. Special focus is made on intuitive and qualitative approaches, more particularly in science and technology. The application Contact described here has been developed at CEGELY within this project. Ist objective is to allow students to intuitively understand how the magnetic eld arranges inside a magnetic circuit when varying geometrical, electrical and magnetic parameters. Contact takes into account the non-linearity of the materials, and enables to study the innuence of the saturation. The main problem when designing this application was to give an instant feedback to any modiication of these parameters: in other words, any user interaction has to induce a modiication of the displayed results in real time. The nite element method is used to compute the distribution of the magnetic eld. Great optimization of its implementation enabled then a real-time solving. The studied geometry is shown in Fig. 1. It is the 2D cross-section of the magnetic circuit of a double-U shaped contactor. The magnetic eld is created by one or two DC coils located on each arm of the contactor. Using the corresponding arrow buttons (see Fig. 2), the user may modify the airgap, the current and the number of turns of both coils, and the deenition of the B-H curves for both arms of the contactor: the relative permeability at the origin of the B-H curve and the ux density at saturation.