Krzysztof Górecki

This paper concerns the modeling of the static and dynamic characteristics of the SEPIC converter. Simulation models of this system were developed for three different programs: SPICE, PLECS, and ANSYS Simplorer. These models utilized the built-in models of the passive and semiconductor components present in each of the considered programs. Additionally, an electrothermal model of this converter was formulated for SPICE. Transient analyses of the considered system were performed using all presented models, and the obtained calculation results were compared with the measurement results. The conditions under which the calculation results were obtained for the mentioned programs were identified. The calculation times for the individual programs and the considered electronic component models were also compared. The presented results show that the most accurate are those analyses performed using ANSYS Simplorer and SPICE with the electrothermal model. The fastest are those analyses performed using PLECS, and the most time-consuming are those analyses performed using SPICE with the electrothermal model.

This paper presents the results of experimental studies illustrating the characteristics of a prosumer photovoltaic system incorporating an energy storage device. The structure of the tested system and its component parameters are described. The measurement procedure and the results are presented, illustrating the influence of time of day and season on the characteristics of the tested system. Based on the obtained results, the impact of weather conditions on energy production by the system on selected days is discussed. The charging and discharging processes of the energy storage device are also analyzed at selected times of day and year.

This paper proposes a manner of modeling properties of stationary and tracking photovoltaic installations. A SPICE-based model of such photovoltaic installations is proposed. With the use of this model, the properties of two photovoltaic installations located adjacent to each other are compared. The first is stationary, while the second is equipped with a solar-tracking system. The design of both installations is described. The results of measurements and computations for both installations are presented and compared. These results illustrate the daily changes in the generated power. These measurements and computations were conducted for selected days across four seasons. The energy produced by each installation in each month was also determined. The obtained results are discussed. It was demonstrated that the use of a solar tracker can significantly increase annual energy production, especially during months with a high solar trajectory. The presented research results demonstrate that the developed model provides accurate predictions of the performance of both photovoltaic installations and that their efficiency is strongly influenced by seasonal meteorological conditions.

This paper analyzes the properties of two photovoltaic installations located in close proximity to each other. One is stationary, while the other abruptly changes the orientation of its panels, which follow the apparent daily movement of the Sun. Measurement results illustrating the daily variations in the productivity of both installations across four seasons are presented and discussed. The rationale for using a mobile installation on the analyzed days is demonstrated.

W pracy przedstawiono wyniki badań eksperymentalnych dotyczących opracowanego układu wspomagającego rytm dobowy człowieka za pomocą źródła światła LED (Light Emitting Diode). Opisano podstawowe elementy opracowanego układu oraz ich parametry eksploatacyjne, a także krótko scharakteryzowano wykonywane przez nie funkcje. Opisano układ pomiarowy, który pozwolił na rejestrację parametrów eksploatacyjnych zaproponowanego układu. Przedstawiono również algorytm sterujący opracowanym urządzeniem. Wyniki badań eksperymentalnych dowodzą, że opracowany układ sterujący czterokanałowym źródłem światła LED spełnia zadanie regulacji rytmu dobowego człowieka.

The article describes the results of research on the power supply quality of selected fluorescent lamps and solid-state light sources powered by voltage with different waveforms and supply voltage values. The power factor, total harmonic distortion (THD) factor and values of individual harmonics were measured and their compliance with international standards was assessed. The measurement set-up used and the measurement results obtained with it are described. The results of the experimental research showed that the light sources under consideration did not meet the criteria specified in international standards for the THD factor and the values of individual harmonics, regardless of the shape of the supply voltage waveform. Current total harmonic distortion always exceeded 44%, exceeding the upper limit of 23% specified in the IEC 61000-3-2:2018 standard. The third harmonic values far exceeded the 21.6% of the first harmonics, which is the limit specified in this standard as well. However, it was shown that supplying some light sources with a triangular voltage waveform can increase the illuminance value by up to 28%. On the other hand, the use of a rectangular voltage waveform leads to an increase in the power factor and a decrease in reactive power.

This paper presents the results of modeling and measuring the thermal properties of selected planar transformer designs. A compact thermal model for the steady state of the planar transformer is presented. A method for measuring its parameters is discussed. The investigation results, illustrating the practical usefulness of the considered thermal model for describing the thermal properties of transformers containing ferrite cores made of different materials, are presented and discussed. The influence of the transformer’s operating frequency and load resistance on the temperatures of each component of the tested transformers is discussed. It is demonstrated that the proposed model enables the correct determination of these steady-state temperatures over a wide range of operating conditions for transformers with cores made of different ferrite materials.

The article describes the results of research on the power supply quality of selected fluorescent lamps and solid-state light sources powered by voltage with different waveforms and supply voltage values. The power factor, total harmonic distortion (THD) factor and values of individual harmonics were measured and their compliance with international standards was assessed. The measurement set-up used and the measurement results obtained with it are described. The results of the experimental research showed that the light sources under consideration did not meet the criteria specified in international standards for the THD factor and the values of individual harmonics, regardless of the shape of the supply voltage waveform. However, it was shown that supplying some light sources with a triangular voltage waveform can increase the illuminance value. On the other hand, the use of a rectangular voltage waveform leads to an increase in the power factor and a decrease in reactive power.

This paper analyses a method for measuring the magnetization curves of ferrite and nanocrystalline materials and determining the loss of the ferromagnetic material used in inductor and transformer cores. Analogue and digital methods for determining B(H) characteristics and the corresponding measurement setup are described. Limitations of the analogue method are highlighted, and example magnetization characteristics obtained using both methods over a wide range of flux density amplitude and frequency changes are shown and discussed. Using the magnetization curves measured using both methods, the dependence of the loss of the tested cores on the frequency and amplitude of flux density was determined. It was demonstrated that the classical analogue hysteresis method produces distorted B(H) waveforms and significantly overestimated values of loss for the tested materials compared to the manufacturer’s data. An analysis was also conducted of the suitability of the classical Steinmetz model for modelling the dependence of the loss of the considered materials on the frequency and amplitude of magnetic flux density. It was demonstrated that the coefficients in this formula should be dependent on the above-mentioned quantities to achieve satisfactory accuracy between the model and the manufacturer’s data. Using a digital method for measuring the hysteresis loop of a ferromagnetic core and measuring its temperature using an optical method, the thermal resistance values of the tested cores were determined. Using the digital measurement method and the modified Steinmetz formula, a significant improvement in the accuracy of determining the losses of ferrite and nanocrystalline cores was achieved.