Ivan Flegar

Flux Reflection Model of the Ferroresonant Circuit

The paper presents a linear model of ferroresonant circuit with flux reflection. The proposed model—flux reflection model—derives from observations of typical flux waveforms of nonlinear coil during ferroresonant steady states. Simulation results of the flux reflection model are compared with simulation results of the usual nonlinear model as well as with measurements carried out on the physical model of the ferroresonant circuit. The flux reflection model enables a novel comprehension of the ferroresonant circuit behavior and simplifies the modeling of the nonlinear coil in the ferroresonant circuit.

Bifurcation diagrams of the buck converter

The steady-state responses of the buck converter are determined by means of computer simulation and presented in a form of one-parameter bifurcation diagrams and two-parameter bifurcation diagrams. It is shown that the analysed converter can be driven into chaos through a process of period doublings; for each of the three chosen bifurcation parameters: the input voltage, the load inductance and the period of the external sawtooth ramp voltage. The results of simulation agree well with those obtained by measurements carried out on a physical model of the circuit.

Steady-state responses of the boost converter

A boost converter controlled by naturally-sampled constant frequency pulse-width modulation in a discontinuous conduction mode of operation is analysed. Several steady-state responses are recognised by varying the dc input voltage only. The analysis of steady-state responses is carried out in the time- as well as in the frequency-domain. A reasonable accordance between results of computer simulation and experiments in both domains is obtained.

Bifurcation diagrams - insight into the modes of operation of a boost converter

The modes of operation of the boost converter controlled by naturally-sampled constant frequency pulse-width modulation in discontinuous conduction mode of operation are determined. Bifurcation diagrams as a principal tool for the qualitative evaluation of behaviour of non-linear dynamical systems are used. It is shown that the boost converter considered here can be driven into chaos through a process of period doubling by varying some parameters of the boost converter: the input voltage, the capacitance of the output condenser, the inductance of the input inductor, period of external sawtooth ramp voltage (period of operation) and the load resistance.

Some general properties of power electronic conversion networks

ContentsThe conversion capability of power semiconductor devices used in power electronic conversion networks is explained. A general power electronic conversion network is defined and the general power relationships relating the real power transferred through the conversion network with the real power transformed by means of conversion devices are derived. Starting from the general power relationships, the poperties of power electronic conversion networks for rectification, inversion, frequency conversion and d.c. conversion are explained. All properties are derived disregarding the internal structure of particular conversion networks.ÜbersichtDie Umformungsfähigkeit der in Leistungselektronik-Umformernetzen eingesetzten Halbleiterbauelemente wird erläutert. Ein allgemeines Leistungselektronik-Umformernetz wird definiert. Die allgemeinen Leistungsbeziehungen werden ausgeführt, welche die durch das Umformernetz übertragene Wirkleistung mit der mittels Umformerbauelemente umgeformten Wirkleistung in Zussammenhang bringen. Ausgehend von den allgemeinen Leistungsbeziehungen werden die Eigenschaften der Leistungselektronik-Umformernetze für Gleichrichtung, Wechselrichtung, Frequenzumformung und Gleichstromumformung erläutert. Alle Eigenschaften werden ohne Berücksichtigung der inneren Struktur einzelner Leistungsumformernetze abgeleitet.