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Control Strategy of Parallel Hybrid Filter for Harmonic Mitigation
Škramlík, Jiří ; Valouch, Viktor
The strategy features a small sensitivity against a disturbed supply voltage system and enables us to set grid phase currents in the phase with respective voltages. The expected properties of the PHF control system have been confirmed by experimental tests in the laboratory. The data show that the modified control strategy yields better results than those obtained by using control systems reported previously, especially in case of an unsymmetrical and non-sinusoidal voltage system and the demand of zero reactive power withdrawn from the grid.
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Porovnání 2D a 3D modelu dávkovače zinku
Mach, M. ; Musil, Ladislav
The paper deals with the mathematical and computer modelling of electromagnetic zinc feeder, which is a device for exact dosing of molten zinc. 2D and 3D models of the feeder were developed, solved and the results were compared and discussed. Computations were carried out by the professional FEM-based codes FEMLAB, OPERA, QuickField and a number of single-purpose user procedures written by the authors
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Porovnání magnetického pole vně a uvnitř trolejbusu 21 Tr řízeného GTO nebo IGCT tyristorem
Nečesaný, Jakub ; Doležel, Ivo
This work is focused on the magnetic field modelling and analysis inside the trolley bus 21TR. Mathematical description is presented. Computation is carried out for accelerating regime for application of two different power switching semiconductor devices GTO and IGCT. Study of the magnetic field is done for head level of standing and sitting people. Local maximum of the magnetic field is also determined. Differences between magnetic field levels given by GTO and IGCT power switching semiconductor devices are consecrated. Finally, geometrical convergence of this problem is evaluated
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Posuvný indukční ohřev a související jevy v kvazi-sdružené formulaci
Karban, P. ; Ulrych, B. ; Doležel, Ivo
The paper deals with quasi-coupled numerical solution of the problem of induction heating and associated phenomena in 2D axisymmetric arrangements. The process of heating is modeled by a special algorithm respecting the temperature dependencies of various material properties and (when necessary) time variable boundary conditions. The algorithm fully developed by the authors is illustrated on an example of continual induction hardening
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Power Electronics and Quality of Electrical Energy
Valouch, Viktor
The paper deals with basic problems concerning the application of power electronic converters in the field of electric power engineering with the aim of improving power quality in transmission and distribution systems. The attention is focused mainly on questions of converter power circuits, their control algorithms, and on modeling and simulation of respective systems. Basic power theories are mentioned as well.
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Alternative Utilisation of a Matrix Converter
Flígl, S. ; Lettl, Jiří
The matrix converter seems to be the final name of one of the older static direct frequency changer power electronics circuit configuration, which finds once again new utilisation. This switch topology has the cycloconverter advantage of lacking a DC link, and hence lacks an energy store, while offering a potentially unlimited frequency range.
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Polařský a obvodový model dávkovače zinku
Musil, Ladislav ; Praglowska-Gorczynska, Z.
Electromagnetic feeders of molten metals are used in some industrial technologies, particularly for accurate dosing. Mathematical model of such devices represents a complicated coupled task characterised by interaction of electromagnetic, temperature and flow fields. The paper deals with numerical computation of several important quantities of the device providing its circuit parameters
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