Wyniki wyszukiwania - BazTech

1

Historia w kamieniu [Muzeum Historii Polski]

Grodzki P., Budzisz K.

Builder

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2018

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R.22, nr 11

196--199

2

Porównanie efektywności iteracyjnej metody rozwiązań fundamentalnych i metody elementów skończonych w analizie zagadnień elektrostatyki

Pawłowski S., Plewako J., Grodzki P.

Przegląd Elektrotechniczny

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2017

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R. 93, nr 12

135--138

PL

(MES) na podstawie analizy rezultatów testów numerycznych przeprowadzonych na modelowym zagadnieniu elektrostatyki. Stwierdzono, że za pomocą IMRF można uzyskać rozwiązanie o danej dokładności w czasie wielokrotnie krótszym (nawet kilkadziesiąt razy) niż za pomocą MES.

EN

The article presents efficiency comparison of the iterative method of fundamental solutions (IMFS) and finite element method (FEM), based on the analysis of numerical tests results obtained for the model of electrostatics problem. It has been found, that applying the IMFS a solution of assumed accuracy could be obtained numerous times shorter (even several dozen times) than using the FEM.

3

Analysis of the proximity and skin effects on copper loss in a stator core

Młot A., Korkosz M., Grodzki P., Łukaniszyn M.

Archives of Electrical Engineering

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2014

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Vol. 63, nr 2

211--225

EN

Accurate prediction of power loss distribution within an electrical device is highly desirable as it allows thermal behavior to be evaluated at the early design stage. Three-dimensional (3-D) and two-dimensional (2-D) finite element analysis (FEA) is applied to calculate dc and ac copper losses in the armature winding at high-frequency sinusoidal currents. The main goal of this paper is showing the end-winding effect on copper losses. Copper losses at high frequency are dominated by the skin and proximity effects. A time-varying current has a tendency to concentrate near the surfaces of conductors, and if the frequency is very high, the current is restricted to a very thin layer near the conductor surface. This phenomenon of nonuniform distribution of time-varying currents in conductors is known as the skin effect. The term proximity effect refers to the influence of alternating current in one conductor on the current distribution in another, nearby conductor. To evaluate the ac copper loss within the analyzed machine a simplified approach is adopted using one segment of stator core. To demonstrate an enhanced copper loss due to ac operation, the dc and ac resistances are calculated. The resistances ratio ac to dc is strongly dependent on frequency, temperature, shape of slot and size of slot opening.

4

Wpływ efektu zbliżeniowego i naskórkowości na straty mocy w tworniku

Młot A., Korkosz M., Grodzki P., Łukaniszyn M.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 12

44-48

PL

W artykule przedstawiono analizę strat mocy w żelazie i miedzi przy zasileniu uzwojenia sygnałem sinusoidalnym o wysokich częstotliwościach. Straty mocy wyznaczone z modelu matematycznego silnika zweryfikowano z pomiarami jakie wykonano na zbudowanym prototypie rdzenia stojana silnika komutatorowego z nawiniętym uzwojeniem. W badaniach uwzględniono wpływ efektu naskórkowości oraz efektu zbliżeniowego na straty mocy w miedzi. Głównym zagadnieniem w pracy było zbadanie wpływu pola magnetycznego połączeń czołowych uzwojeń na straty mocy, poprzez porównanie obliczeń na modelach dwuwymiarowych (2D) i trójwymiarowych (3D) opartych na metodzie elementów skończonych (MES).

EN

Accurate prediction of power loss distribution within an electrical device is highly desirable as it allows for thermal behavior to be evaluated at the early design stage. This paper focuses on the ac copper loss caused by circulating current effects in electrical machines. Two different phenomena lead to additional ac losses: skin effect and proximity effect. Skin effect is the tendency for high frequency currents to flow on the surface of a conductor and can be mitigated through the use of small conductor strands. The proximity effect is the tendency for current to flow in other undesirable patterns that form localized current loops or concentrated distribution due to the presence of a magnetic field generated by nearby conductors. To evaluate the ac copper loss within the analyzed machine a simplified approach is adopted utilizing the segmented stator topology. To minimize and show an effect of proximity and/or end-winding on the ac copper loss at presented electrical machine a number of winding arrangement are investigated. Three-dimensional and two-dimensional finite element analysis was applied to calculate a ratio of ac to dc resistant at high frequency sinusoidal current. This resistant ratio demonstrates the amount of copper loss which is increased by high frequency. The resistant ratio is strongly dependent on frequency, temperature and shape of slot and size of slot opening. The theoretical finding is compared against the experimental data of total power losses.