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Vliv vybraných parametrů na vlastnosti asynchronního generátoru
Schreier, Luděk ; Bendl, Jiří ; Chomát, Miroslav
The paper deals with the problems associated with the estimation of the magnetizing current in generator operation of induction machines. According to some experts, the magnetizing current in generator operation is considerably bigger than that in motor operation and this fact must be taken into consideration while designing the magnetic circuit. It is shown that this opinion is not justified in case of generators with output power about 30 kW and higher.
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Balancování napětí na 4-hladinovém napěťovém střídači s plovoucími kondenzátory
Kokeš, Petr ; Semerád, Radko
This paper deals with voltage balancing, which is a specific problem in multilevel voltage source inverters (VSI). The reasons for choosing a capacitor-clamped VSI for the solution of our project are stated, and the basic principle of such VSIs and the demands on balancing their flying capacitors are explained. A control algorithm for the voltage balancing of a 4-level capacitor-clamped VSI is suggested. The implementation of the balancing algorithm is also discussed. The results obtained from computer simulations in the time domain demonstrate the operating capability of the proposed balancing algorithm in an 850 kW induction motor drive.
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Výkonost pohonu s proměnnými otáčkami při napájení nesymetrickým napětím
Chomát, Miroslav ; Schreier, Luděk ; Bendl, Jiří
Unsymmetrical voltages at the input of a voltage source inverter cause pulsations in the DC-link voltage when not properly taken care of. This may result in reduced power capabilities of the drive. The unbalance can be caused by a failure in the network or by unbalanced load in the vicinity of the affected drive. The paper deals with the methods to address this problem and with the limitations placed on the drive when operated from the unbalanced voltage supply.
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Aktuátor založený na principu termoelasticity pro vytváření extrémních sil
Doležel, Ivo ; Donátová, M. ; Karban, P. ; Ulrych, B.
Actuators working on the principle of thermoelasticity represent promising devices for fixing tasks in the industrial environment. The paper deals with the computer simulation of their operations both in the dynamic regimes. The task represents a multiply coupled problem characterized by interaction of electromagnetic field, temperature field and a field of thermoelastic displacements. The corresponding mathematical model is solved in hard-coupled formulation. The methodology is illustrated on a typical example.
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