Purpose. The paper analyzes the system and methods of starting synchronous electric motors of fans of the main ventilation of iron ore mines. It is concluded that it is necessary to modernize the method of starting a synchronous electric motor, despite the fact that the installed direct start-up system has a number of disadvantages, and negatively affects the energy indicators of the electromechanical complex of the main ventilation fan of mines. The priority direction in solving the complex of the above problems is the use of modern achievements in the field of semiconductor conversion technology, in terms of the development of effective circuits and methods for starting and controlling a synchronous electric drive. Originality. The method of separate regulation of size and frequency of output voltage of the multilevel converter of a clock at quasi-frequency start of the synchronous electric drive is offered, limits admissible values of starting currents to admissible values. Methodology. Simulation of transient processes of starting a synchronous electric motor with step-by-step changes in voltage and frequency of supply, which made it possible to determine the energy efficiency of this method. Result. A new method of starting with a step-by-step change in the voltage and frequency of a synchronous motor is proposed. The modeling of the proposed starting method for a synchronous electric motor with a fan torque on the motor shaft was carried out, while it allowed to get rid of the main drawback, namely, a large starting current and made it possible to increase the energy efficiency of the electromechanical complex of the main ventilation fans due to the fact that the consumed active energy during start-up will decrease approximately 50% compared to a direct starting system. Practical value. The proposed method and the obtained results of the study made it possible to prove that the effectiveness of the proposed method is very high and this will save most of the electrical energy when starting the fans of the main ventilation of iron ore mines. Figures 15, references 15
The research deals with analyzing peculiarities of using active rectifiers in frequency controlled electric drives of underground mine hoists. There are developed MATLAB models aimed at comparing two types of control systems – hysteresis-based and the one with pulse-width modulation. The research aims to analyze power modes and parameters of active rectifiers, quality of voltage control, current and power of active rectifiers and to determine ways of improving power indices of electric equipment of hoists as well as provide power compatibility of electric equipment and underground mines’ grids. Main attention is paid to analyzing circuitry of control systems of active rectifiers, parameters of power transformers and reactor equipment at underground mines’ substations, frequency converters and synchronous slow-speed motors. There are also analyzed statistic data on power consumption at underground mines equipped with automated systems of commercial and technical power meters and specific consumption of power. The research results reveal advantages of the pulse-width modulation control system as compared with the hysteresis one by using such indices as speed-performance, quality of control, potential of controlling reactive power and the power factor. Application of the research results will enable determining structures and methods of adjusting control over the active rectifier in the frequency-controlled drive of underground mine hoists.
Анотація-У статті наведені результати дослідження явищ при короткочасному відриві пантографу рудникового електровозу типу 14КА з системою частотного електроприводу інвертор напруги-асинхронний двигун. Мережа електропостачання враховується як некерований випрямляч, який отримує живлення від джерела напруги, з тролеями, які враховуються як послідовне сполучення індуктивного та активного опорів. Рейки також враховуються як малий активний опір. Дослідження проводились за допомогою імітаційного моделювання. При моделюванні інвертор електровозу відключався від мережі два рази послідовно на час 0,05 с. Утворення дуги при розриві індуктивного струму при цьому не враховувалося. Було встановлено, що, при розриві виникають значні високочастотні коливання в мережі величиною до 40 кВ, а при відновленні контакту з мережею виникають значні струми вмикання та пікові електромагнітні моменти, що багатократно перевищують номінальний момент двигуну. Отримані результати досліджень приводять до необхідності подальшого вдосконалення частотного приводу стосовно використання на шасі рудникового електровозу, для зменшення негативних явищ при відриву пантографу від тролею. Бібл. 10, рис. 5. Ключові слова-шахтний електровоз; пантограф; мережа електропостачання.
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