MODELING OF ELECTROMECHANICAL CHARACTERISTICS OF TRACTION ELECTRIC MOTORS OF ROLLING STOCK

Purpose. The purpose of the scientific research is to develop a methodology for modeling the electromechanical characteristics of traction electric motors of direct and pulsating current of traction rolling stock of main and industrial railway transport. Mathematical modeling of the electromechanical characteristics of traction electric machines is a necessary condition for conducting traction calculations and studying transient processes in traction electric drives of rolling stock by analytical methods. Currently, there are a number of scientific works that usually consider graph-analytical methods of traction calculations, which limit existing methods for optimizing train movement modes. In connection with the above, it can be concluded that research aimed at modeling the electromechanical characteristics of traction electric machines of direct and pulsating current is relevant. Methodology. The methodological basis of the scientific research is the general theoretical provisions and principles of the system approach of theoretical electrical engineering, the theory of electric machines and converters. The justification of the method for determining the coefficients approximating the dependence of the specific electromotive force of a traction motor on the excitation current was carried out using the principles and methods of the theory of electric circuits, the theory of electric and magnetic machines, and known methods of mathematical analysis. The minimum mean square deviation of the model from the original characteristic was chosen as the criterion for the correctness of the approximation. Findings. As a result of the analysis, it was proven that of all the known analytical expressions by which the magnetization curve of traction electric motors can be simulated, the best approximation is given by an expression in the form of an arctangent function. When simulating the electromechanical characteristics of real traction electric motors of electric locomotives, the relative deviation from the real speed characteristics does not exceed two percent, which is less than the permissible deviation of the rotational speed of traction electric machines from its nominal value. When using the proposed method, it is possible to determine the approximation coefficients in the equations that model the electromechanical characteristics of traction electric motors, using the typical parameters of the traction electric machine, without using the characteristics themselves. Originality. A convenient and effective method for determining the approximation coefficients of the magnetic characteristic of traction electric motors of direct and pulsating current has been proposed, which differs in that it allows mathematical modeling of the electromechanical characteristics of traction electric motors only using their typical parameters. Practical value. The proposed method for determining the approximation coefficients of the magnetic and corresponding electromechanical characteristics can be used when performing traction calculations by the analytical method, when analyzing transient electromechanical processes in traction electric motors, and also for selecting rational parameters of automatic control systems for traction electric drives.