Showing papers by "Janusz Zarębski published in 2013"

The method and circuit for measuring own and mutual thermal resistances of a magnetic device

Abstract: The method for measuring the own thermal resistance of a magnetic device consists in that the winding resistance, whose thermometric characteristics slope describes the temperature coefficient of copper resistivity changes ρ Cu , is measured as a thermally sensitive parameter. The measurement is carried out in at least three stages, including in turn measurements and calculations based on analytical formulae. The measurement of the own thermal resistance of a magnetic device in the form of a choking-coil is carried out in three stages, while the measurement of the own thermal resistance of a magnetic device in the form of a transformer is carried out in five stages. At the first stage of measurement the winding resistance is measured at a low value of the choking-coil current and the core temperature is measured using a radiometric pyrometer. At the second stage measurements are made, in a thermal steady state, of the winding resistance and, with a radiometric pyrometer, the core temperature at a high value of the current. At the third stage the value of the winding thermal resistance and the mutual thermal resistance between the core and the winding are calculated from given formulae. In the case of a transformer, at the fourth stage a sinusoidal signal is applied across the primary winding and the waveforms of the primary winding current and a voltage across a capacitor are measured using an oscilloscope. The core temperature is also measured. At the fifth stage the value of the core thermal resistance is determined based on given formulae. The circuit for measuring own and mutual thermal resistances of a magnetic device comprises voltmeters, ammeters, an oscilloscope, DC voltage sources, double-throw switches, a radiometric pyrometer, a source of sinusoidal signal, resistors and a capacitor.

Parameter estimation of the electrothermal model of the ferromagnetic core

Abstract: The paper presents a form of the electrothermal model of the ferromagnetic core for SPICE and the way, in which parameters of the model are determined. The manner of determining magnetic, geometric and thermal parameters of this model is described. The correctness of the proposed model and the manner of determining the values of parameters are verified by comparing the calculated and measured characteristics of the selected ferromagnetic cores.

Measuring system for determining thermal parameters of semiconductor devices

Abstract: In the paper the measuring system, elaborated by the authors, for determining thermal parameters of semiconductor devices with the use of electrical methods, is presented. The concept of operation of the system and a sample circuit solution dedicated for measurements of diodes are described. Correctness of the system's operation was verified by comparing the results of transient thermal impedance measurements of the silicon Schottky diode and the silicon carbide MPS diode, obtained through the developed measuring system and pyrometric method.

Wpływ doboru rdzenia dławika na charakterystyki przetwornic boost

Abstract: Streszczenie. W pracy przedstawiono wyniki pomiarow charakterystyk przetwornicy boost uzyskanych z zastosowaniem dlawikow z roznymi rdzeniami ferromagnetycznymi. Otrzymane wyniki badan wskazują, ze rdzenie ze sproszkowanego zelaza powinny byc uzywane w przetwornicach o malej rezystancji obciązenia, a rdzenie ferrytowe – w przetwornicach pracujących przy duzych rezystancjach obciązenia. Rdzenie nanokrystaliczne umozliwiają uzyskanie trybu CCM w szerokim zakresie zmian rezystancji obciązenia.