Ресурсозберігаюче регулювання напруги асинхронних двигунів зі зниженням навантаження

Abstract

UA: У роботі розглянуто методи керування асинхронними двигунами за мінімумом витрати ресурсу. Встановлено, що більшість із них спрямовані на контроль втрат потужності й не враховують швидкості зношення елементів конструкції електродвигуна. Для можливості здійснення ресурсозберігаючого керування запропоновано як критерій оцінювання застосовувати швидкість теплового зношення ізоляції обмотки статора асинхронного двигуна. Розроблено математичну модель процесу теплового зношення ізоляції обмотки, за допомогою якої отримано рівняння кратності живлячої напруги у функції коефіцієнта завантаження за умови мінімуму швидкості теплового зношення ізоляції. Це дає можливість будувати алгоритми та пристрої регулювання напруги живлення електродвигуна для збереження його ресурсу зі зниженням навантаження. /// EN: The article is devoted to improving the reliability of asynchronous motors used to drive working machines and mechanisms. These electric motors are most widely used in practice due to their high structural reliability and relatively low cost. However, operational experience has shown that their reliability decreases in production conditions. This is due to external influences that were not fully anticipated during the design phase. One such influence is variable loading from the working machines. Therefore, researching its effect on the service life of asynchronous motors and developing a resource-saving effect on electric motors when the load changes is a pressing task. This task can be solved by implementing a specific control method. An analysis of existing methods has shown that most of them are aimed at controlling power losses and do not take into account the rate of wear of electric motor components. Therefore, the article aims to justify a method of resource-saving control of asynchronous motors under changing load conditions by regulating the voltage The rate of thermal wear of the stator winding insulation is accepted as the criterion for preserving the resource of an electric motor during its operation. The main factor affecting it is the current excess of the winding temperature. The paper considers the expression of temperature excess as a function of constant and variable active power losses in an electric motor. Based on the equivalent circuit of an asynchronous motor, these power losses are presented as a function of the equivalent circuit parameters, load factor and voltage multiplicity. Based on these equations, a mathematical model of the thermal wear process of the winding insulation was developed. Using this model, a study of the change in the service life of the AIR90L4 asynchronous motor was conducted. The results of the study showed that a decrease in the voltage at the terminals of an underloaded electric motor leads to a decrease in its service life. To regulate the voltage at the electric motor terminals, the dependence of the voltage multiple on the load factor of the asynchronous motor was obtained, at which the rate of thermal wear of the stator winding insulation will be minimal. This allows algorithms and devices to be developed for regulating the supply voltage of the electric motor to ensure that its service life is preserved when the load is reduced. The disadvantage of the obtained dependence is that it has only been verified for cases where the electric motor drives working machines with mechanical characteristics that are independent of speed. Further research should be aimed at establishing such dependencies for cases of driving working machines with other types of mechanical characteristics and taking into account the increase in load relative to the nominal value.