Дослідження роботи тягового асинхронного двигуна при несиметрії живильної напруги та аварійних режимах роботи

Abstract

UA: У статті розглянуто імітаційне моделювання прямого пуску тягового асинхронного електродвигуна (АД) з несиметрією живильної напруги в програмному комплексі Ansys Electronics. Було отримано графіки частоти обертання та електромагнітного моменту при введенні несиметрії напруги фази А в 4 % при усталеному режимі роботи тягового асинхронного електродвигуна, а також проведено порівняння з характеристиками при симетричному живленні. EN: The asymmetry of the supply voltage adversely affects the operation of electric motors, in particular induction ones. With an uneven load of the phases of the network, the voltage becomes asymmetric - unequal between the individual phases. Voltage asymmetry leads to the fact that the currents in the phases of the stator winding of the electric motor differ sharply from one another. A phase with a high current can overheat above acceptable limits even with a small voltage unbalance. In addition, the active steel of the motor rotor overheats. Overheating of the motor winding causes an increase in electrical losses, ripples of the electromagnetic torque also appear, and other negative consequences. These factors can lead to process failure, accelerated insulation aging, or even motor failure. In the event of a mains phase failure, running three-phase motors switch to single-phase mode. If the motor load before phase failure was no more than 60% of the rated value, then the motor continues to operate with slightly worse energy performance, the rotor speed decreases slightly, the winding temperature is within acceptable limits. Under heavy loads, the motor winding overheats excessively, and in some cases the motor rotor stops and a large current flows through two phases of the stator winding. After stopping the engine, it cannot be started even at idle, since a pulsating magnetic field is obtained in the engine with a single-phase current. To study the effect of supply voltage asymmetry on the operation of an asynchronous electric motor, simulation modeling was carried out in the ANSYS Electronics software package for direct start of induction motor with the introduction of a supply voltage asymmetry of one of the phases at a level of 4% in the steady state operation of the electric motor. The characteristics of the rotation frequency and electromagnetic torque were obtained with asymmetry of the supply voltage and a comparison was made with the symmetrical mode of operation of the electric motor. The results of simulation show a slight change in the frequency of rotation of the rotor of the electric motor, however, there are significant ripples of the electromagnetic torque.