Computer Aided Design by FEM Method For Eddy-Current Brakes

Computer aided field analysis and design by FEM methods are advanced and cost-effective methods that provide fast and accurate results into various technical design projects. In this paper, a FEM-method-based approach is used to determine eddy-current brake model´s parameters, i.e. equivalent resistance and reactances. The eddy-current brakes are electrical machines that convert, by electrical means, the mechanical energy received to its shaft into thermal energy. The thermal energy produced during the conversion is transferred to a cooling environment such as water or air. These brakes are particularly suitable for load-testing thermal engines on the stationary test-bands. They are also used to improve safety and enviromnental-clean braking of rails and lorries into the high speed ranges. Various dynamic models have been proposed in the literature to describe the dynamic behavior of the eddy-current brakes, despite their uncomplicated construction. In the paper the general two-axis theory is used to obtain the dynamic model of the eddy-current brakes no matter what is the particular structure of the brake. The parameters of the dynamic model of the brake cannot be directly accessed to measurements. However, these values may be determinate by field analysis. In the paper, field analysis by FEM method is used to compute model´s parameters, particularly referring to the transversal-excitation eddy-current brakes. Computer-aided field analysis provides information not only for the computation of the parameters of the dynamic model but also for the optimization of the magnetic´s circuitry shape of the brake. To expound this advantage, in the paper the field analysis is performed on a conventional designed eddy-current brake and compared to experimental measurements.