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1
Content available Novel arrangement of combined star-delta stator winding aimed at reduction of copper usage inelectric machine
Schreier L., Bendl J., Chomat M.
Maszyny Elektryczne : zeszyty problemowe
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2018
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Nr 3 (119)
117--122
EN
The submitted paper deals with the increased energy efficiency of induction machines by means of the so-called combined stator winding. Two basic variants of this winding, the series and parallel ones, are shown. The suppression of higher harmonics is analysed by means of the method of space vectors and symmetrical components. It is shown that the so-called series variant of the combined winding has a better ability to suppress higher spatial harmonics. The commonly used combined winding has, however, a longer pitch and thus bigger stator resistance and greater consumption of copper. The paper presents a proposal of an adapted combined winding whose pitch is smaller than that of the used three-phase winding. This fact results in decreasing the consumption of copper conductors with preserving the energy efficiency. The results of the analysis have been verified by measurements on physical models of machines with the combined and the adapted combined windings.
2
Content available Analysis of properties of induction machine with combined parallel star-delta stator winding
Schreier L., Bendl J., Chomat M.
Maszyny Elektryczne : zeszyty problemowe
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2017
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Nr 1 (113)
147--153
EN
The paper analyses the properties of a machine with a parallel combined stator winding. The analysis has been carried out with regard to the numbers of conductors of delta- and star- connected windings. The paper shows the influence of the ratio of the number of conductors of these windings on the possibility of suppressing higher spatial harmonics and on the efficiency of the machine. The derived equations of the machine with the combined stator winding describe the behaviour of the machine both in a steady state and in transient operating and fault states.
PL
W artykule przeanalizowano właściwości maszyny z równoległym połączeniem uzwojenia stojana. Analizę prowadzono w zakresie liczby przewodów delta i połączonego w gwiazdę uzwojenia. Przedstawiono wpływ stosunku liczby przewodów tych uzwojeń do możliwości stłumienia wyższych harmonicznych przestrzennych i dotyczących sprawności urządzenia. Pochodne równania maszyny z połączonym uzwojeniem stojana opisują zachowanie maszyny, zarówno w stanie ustalonym, nieustalonym oraz podczas awarii.
3
Content available remote Control of Active Front-End Rectifier in Electric Drive under Unbalanced Voltage Supply in Transient States
Chomat M., Schreier L., Bendl J.
Przegląd Elektrotechniczny
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2012
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R. 88, nr 1a
177-180
EN
The situation when voltage-source inverter is supplied with unbalanced system of voltages is investigated. This can cause problems in operation of an electric drive as voltage pulsations can arise in the DC-bus. Suitable control methods may be applied to eliminate this effect in the active front-end rectifier. The paper particularly focuses on transient processes that accompany operation of the drive. They can be caused by changes in control of the drive, changes in load, or changes in the supply voltages.
PL
Zbada no przypadek podłączenia przekształtnika do niezrównoważonego system napięciowego. Może powodować to problemy takie jak pojawienie się pulsacji napięcia w szynie DC. W artykule analizowano procesy przejściowe w sterownikach.
4
Content available Comparison of selected properties of three- and five-phase induction motors
Schreier L., Bendl J., Chomat M.
Maszyny Elektryczne : zeszyty problemowe
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2010
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Nr 88
169-174
EN
The paper analyses the rise of higher space harmonics in three-phase and five-phase induction machines. The results of the analysis show that there is a group of harmonics which are associated with symmetrical components of phase currents. In five-phase machines, the spectrum of higher harmonics assigned to the component which generates the operating torque is shifted to higher orders. Due to this fact, the five-phase machines have several advantages compared with the three-phase machines. These advantages are apparent mainly in a steady-state operation at symmetrical feeding. The five-phase machines have, however, also improved properties in transient and fault states. This fact is shown at the example of operation of three-phase and five-phase machines after the two-phase short circuit at the terminals of two neighbouring phase stator windings. In this case, the five-phase machine can, for a short time, operate with a rated load, while a three-phase machine is not able to generate sufficient torque and the rotor speed rapidly decreases to the standstill.
5
Effect o machine geometry on higher harmonics content in air-gap magnetic field of synchronous reluctance machine
Schreier L., Chomat M., Dolezel I.
Zeszyty Naukowe. Elektryka / Politechnika Śląska
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2001
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z. 176
259-266
EN
The presented paper deals with the effect of rotor geometry on the magnetic field distribution in the air gap. The magnetic field is analysed by means of the finite element method. Thid method represents, however, quite a laborious and time-consuming process. Therefore, a simpler semianalytical method for evaluation of the magnetic field distribution in the air gap and following determination of parameters for a numerical model of the machine based on lumped parameters has been proposed. This model enables considering the effect of a series of higher harmonics of the air-gap permeance on electromagnetic quantities of the machine.
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