W pracy opisano model numeryczny jednofazowego transformatora nadprzewodnikowego. Wprowadzone dodatkowo zależności matematyczne umożliwiły wyznaczenie wartości średniej i skutecznej prądu w kolejnych okresach, a także obliczenie ilości ciepła, które wydziela się w uzwojeniach podczas włączania nieobciążonego transformatora na pełne napięcie sieci zasilającej. Wyznaczono obliczeniowo i porównano przebiegi oraz parametry impulsów prądu włączania transformatora o mocy 21 MVA z uzwojeniami nadprzewodnikowymi.
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The paper discusses numerical models of single-phase superconducting transformers. The addition of mathematical relationships made it possible to determine the average and effective current in subsequent periods, and to calculate the amount of heat that is released in the windings when switching the unloaded transformer to the full voltage of the supply network. The waveforms and impulses of the inrush current of 21 MVA transformers with superconducting windings were calculated and compared.
The paper describes a circuit model of a single phase transformer implemented in PSpice program. The computer model was prepared on the basis of the geometrical and electrical parameters of the 10 kVA transformer with copper windings. Model takes into account Jiles-Atherton equations to simulate nonlinearity of the magnetic core. The no-load, nominal load and short-circuit characteristics generated during the numerical analysis were compared to the measurement results acquired on the physical model.
The renewable energy sources or energy storage devices deliver output voltage at the range of around 12 VDC to 48 VDC. In order to obtain at least 350 VDC needed for direct to alternating current conversion the DC/DC power converter should demonstrate significant voltage gain and power conversion efficiency as high as possible. To obtain such level of output voltage at low input voltages transistors of the boost converter must operate with high currents. High efficiency and high voltage gain can be achieved with parallel combination of two or more isolated step-up converters. The converters operate synchronously and in phase, using the same control signals. Balancing transformers are used to ensure the synchronization and equal distribution of current between the power levels. They provide equal distribution of significant input current to a number of smaller current loops. This feature alongside with the use of power MOSFETs with low channel resistance and silicon carbide (SiC) Schottky diodes will reduce losses within the converter and increase the efficiency of entire energy conversion system. This paper presents PSpice simulation results of partial parallel isolated DC/DC boost converter with voltage doubler. In presented circuit high voltage gain and high conversion efficiency were achieved.
Low-voltage high-current energy sources and energy storage devices such as solar panels, fuel cells, super capacitors and batteries deliver output voltage not exceeding several tens of volts. To meet the electric grid standards that voltage should be adjusted to the system DC Bus voltage of around 400 VDC- High efficiency high voltage gain step-up DC-DC converters ensure that interface. This paper presents simulation results of the isolated full-bridge DC-DC boost converter with voltage doubler. In order to achieve higher efficiency modem power MOSFETs with low channel resistance as well as silicon carbide (SiC) Schottky diodes were used. In presented circuit tenfold voltage gain and high conversion efficiency were achieved. Parametric and transient characteristics along with the features of converter simulation model will be described.
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The paper presents an electrical model developed for Pspice simulation of the behavior of the magnetic amorphous wires (MAW) working under the Giant Magnetoimpedance (GMI) effect. The model was developed in order to facilitate the design of the signal conditioning circuitry belonging to the new category of transducers whose sensitive element is based on the GMI effect. The model is a complex one, owing to the fact that the effect is influenced by many internal or external factors, whose actions have to be taken into consideration. In the paper, an example on how the model can be applied to simulate a Colpitts oscillator is given next to its presentation and analysis.
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