# Факультет електроенерготехніки та автоматики (ФЕА)

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### Перегляд Факультет електроенерготехніки та автоматики (ФЕА) за Автор "Andrii Stulishenko"

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Документ Відкритий доступ Design of a multilink system for calculating high-frequency processes in electric machines with mesh windings(Eastern-European Journal of Enterprise Technologies, 2023) Vadim Chumack; Mykhailo Kovalenko; Oksana Tymoshchuk; Andrii Stulishenko; Yevhen IhnatiukПоказати більше This study considers the design of a multi-link high-frequency circuit for calculating defective and defect-free insula tion of mesh windings in order to increase the operational reli ability of general-purpose electric machines. The object of research is mesh windings of electric machines. The problem to be solved: increasing the operational reli ability of electric machines with general-purpose mesh wind ings by analyzing and modeling defects. The research results make it possible to model defects for the analysis of the state of insulation of electric machines with mesh windings. Special attention in the research was paid to induction motors with a worn-out resource, in particu lar, 4A80A4 UZ engine. The analysis includes phase-to-body capacitance, winding inductance, eddy current impedance, and winding impedance. Under the WN mode, a decrease in the impedance of the winding section from 3 % to the short-circuit mode was simu lated; accordingly, the resonance frequencies for each case of 3 % were determined – 73990 Hz, short-circuit – 74450 Hz, as well as the corresponding input impedances 8938.7 and 8082.5. The corresponding voltage resonances and current resonances were also determined. Appropriate results were also given for the WG scheme. The results reported here relate to the design of the scheme and the research on the defects of the mesh winding. This contributes to the analysis of the state of insulation of mesh windings. The numerical data (resonant frequencies and input impedances) allow a better understanding of the behavior of windings in different states and degrees of defects. Given the research findings, it is possible to better identify and analyze potential defects in mesh windings, which in turn contributes to increasing the reliability of electric machines. The results of this study could be used in the field of diag nosis, service, and maintenance of electric machines with mesh windings.Показати більше Документ Відкритий доступ Research of high-frequency remagnetization model in laminated magnetic cores of electromechanical and electromagnetic energy converters(Eastern-European Journal of Enterprise Technologies, 2023) Vadim Chumack; Oksana Tymoshchuk; Mykhailo Kovalenko; Volodymyr Bazenov; Yevhen Ihnatiuk; Andrii StulishenkoПоказати більше The object of research in the work is charged magnetic conductors of electric machines and transformers. Laminated magnetic wire together with windings are important active parts of electric machines that participate in electromechanical energy conversion.The reliability of the entire machine is mainly determined by the actual condition of the inter-sheet insulation. Violation of the insulation causes parasitic eddy current circuits, which increases the specific losses, and also significantly affects the additional heating of the magnet wire and winding. The normative method for determining the quality of the charged core is the assessment of specific losses at a frequency of 50 Hz and an induction of 1 T, which should not exceed 2.5–4 W/kg. To determine local damage to the core, methods of local heating and fixation of overheating sites are used, which should not exceed 45 °C compared to the main part of the magnetic core. In the work, a two-dimensional field mathematical model of a charged magnetic circuit is developed. This makes it possible to carry out electromagnetic calculations in a near-real magnetic conductor, taking into account the variability of magnetic permeability, hysteresis, and the interaction of currents in adjacent plates of the magnetic conductor with each other, the so-called "proximity effect".On the basis of the developed models, graphs of current distribution and distribution of magnetic induction in one, two and three sheets were obtained. The resulting graphs show how the effect of current displacement increases with increasing frequency, where at a frequency of 100 kHz the magnetic induction density in the middle of the sheet goes to zero. The results of the research confirm the correctness of the model development in comparison with the classical calculation models also given, which allows them to be used for further research of high-frequency processes in charged magnetic circuits of electric machines.Показати більше