Optimum control of an asynchronous electric drive

Abstract

The article proposes the main stages of compiling mathematical models for calculating and analyzing the dynamic and thermal modes of asynchronous motors in systems of an automated frequency electric drive are described. The application of the maximum principle and the Newton-Raphson method is given, as well as the solution of the problem using the maximum principle, which leads to a doubling of the number of differential equations. Under these conditions, the search for the initial values of auxiliary functions by the Newton-Raphson method is complicated by a circumstance associated primarily with the convergence of the method, since the convergence region occupies a small part of the coordinate space around the desired optimal point. To determine the required initial approximations, new method variable shift steps are proposed. The proposed method for improving the region of convergence of the Newton – Rafson method make it possible to calculate the optimal control parameters of a frequency-controlled asynchronous electric drive. Based on the calculation results, the curves of the basic and optimal starts of an asynchronous motor in a constant flow mode for the optimization criteria in terms of speed and minimum heating were obtained. On the basis of calculations and analysis of dynamic characteristics, practical conclusions were made. The results provide scientifically grounded recommendations to developers, designers and operators, as well as allow to improve the energy and performance indicators of automated frequency-controlled asynchronous electric drives intended for sectors of the national economy.