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1.
Merjenje karakteristik eksplozijsko varnega asinhronskega elektromotorja : diplomsko delo
Andrej Drnovšek, 2023, undergraduate thesis

Abstract: V industriji se zelo pogosto uporabljajo električni stroji in naprave, med katere sodijo tudi asinhronski elektromotorji. Težava nastane takrat, kadar se asinhronske elektromotorje potrebuje na tako imenovanih eksplozijsko nevarnih področjih. To so področja, kjer so prisotne koncentracije vnetljivih plinov ali tekočin in bi posledično lahko ob prisotnosti iskre, električnega toka ali visoke temperature prišlo do eksplozije. Ker ta področja industrije ne morejo obratovati brez asinhronskih elektromotorjev, se je v ta namen razvil poseben tip oziroma izvedba. Takšna izvedba se imenuje eksplozijsko varna, in ima lastnost, da tudi če bi zaradi katerega izmed zgoraj navedenih razlogov prišlo do eksplozije, se le-ta ne bi razširila v okolico. Ker je v današnjih časih potreba po eksplozijsko varnih asinhronskih elektromotorjih vse večja, je celotno diplomsko delo orientirano k njim. Natančneje cilj diplomskega dela je merjenje karakteristik eksplozijsko varnega asinhronskega elektromotorja, s poudarkom na merjenju izkoristka za razred IE3. Pri tem so bile opravljene meritve na prototipnem eksplozijsko varnem asinhronskem elektromotorju, v dveh različnih merilnicah. Predhodno je bil opravljen še analitični izračun z zato namenjeno programsko opremo. Povsem na koncu diplomskega dela pa je sledila še natančna analiza rezultatov, v smislu neposredne primerjave rezultatov iz obeh merilnic, z rezultati, dobljenimi s pomočjo analitičnega izračuna.
Keywords: asinhronski elektromotor, eksplozijska varnost, tipsko preizkušanje, analitični izračun
Published in DKUM: 18.01.2024; Views: 112; Downloads: 15
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2.
Simplified method for analyzing the availability of rooftop photovoltaic potential
Primož Mavsar, Klemen Sredenšek, Bojan Štumberger, Miralem Hadžiselimović, Sebastijan Seme, 2019, original scientific article

Abstract: This paper presents a new simplified method for analyzing the availability of photovoltaic potential on roofs. Photovoltaic systems on roofs are widespread as they represent a sustainable and safe investment and, therefore, a means of energy self-suffciency. With the growth of photovoltaic systems, it is also crucial to correctly evaluate their global effciency. Thus, this paper presents a comparison between known methods for estimating the photovoltaic potential (as physical, geographic and technical contributions) on a roof and proposes a new simplified method, that takes into account the economic potential of a building that already has installed a photovoltaic system. The measured values of generated electricity of the photovoltaic system were compared with calculated photovoltaic potential. In general, the annual physical, geographic, technical and economic potentials were 1273.7, 1253.8, 14.2 MWh, and 279.1 Wh, respectively. The analysis of all four potentials is essential for further understanding of the sustainable and safe investment in photovoltaic systems.
Keywords: photovoltaic system, rooftop photovoltaic potential, economic potential, light detection and ranging, LiDAR
Published in DKUM: 05.12.2023; Views: 192; Downloads: 9
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3.
Conference proceedings
2019, proceedings of peer-reviewed scientific conference contributions (international and foreign conferences)

Abstract: Konferenčni zbornik / 7. mednarodni simpozij o aplikativni elektromagnetiki SAEM 18. Mednarodni Simpozij o Aplikativni Elektromagnetiki je namenjen predstavitvi rezultatov raziskovalnega dela na različnih področjih aplikativne elektromagnetike. Simpozij je namenjen izmenjavi idej, predstavitvi dosežkov in rezultatov, zagotavljanju foruma za raziskovalce in akademike. Naše konference so znane po odprtem in prijaznem vzdušju, ki spodbuja zlasti mlade raziskovalce, da predstavijo svoje dosežke in ideje še v zgodnji fazi njihovega raziskovalnega dela. Simpozij nadaljuje tradicijo skupnih konferenc, ki so bile v preteklih letih organizirane v Makedoniji, Poljski, Sloveniji in Madžarski. Simpozij je odprt za udeležence iz vsega sveta. Letošnji simpozij je potekal med 17. in 20. junijem 2018 v Podčetrtku, Slovenija.  Vsem udeležencem se zahvaljujemo za sodelovanje na mednarodnem simpoziju o Aplikativni elektromagnetiki in jih želimo uspešno akademsko kariero.
Keywords: applied electromagnetics, electrical machinesn, electromagnetic field, electromagnetic devices, energy efficiency
Published in DKUM: 04.12.2023; Views: 243; Downloads: 8
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4.
Accuracy of Rotational Speed and Torque Sensors for Determining the Mechanical Power of Rotating Electrical Machines
Gregor Srpčič, Iztok Brinovar, Bojan Štumberger, Sebastijan Seme, Miralem Hadžiselimović, 2019, published scientific conference contribution

Abstract: This paper deals with determining the accuracy of measuring systems for determining the characteristics of rotating electrical machines. Efficiency classes and experimental methods for determining efficiency, are given in a standard, which has to be strictly respected. For determining the efficiency of an electrical machine, it is necessary to have a modern and accurate measurement system with sensors of high accuracy classes, which enables the user to carry out precise measurements and consequently, to determine all the characteristics of the electrical machine. This paper will be focused on torque and speed measurements.
Keywords: efficiency, measuring system, electric machines, torque and rotational sensors, accuracy
Published in DKUM: 04.12.2023; Views: 217; Downloads: 11
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5.
Energy Efficiency Indicators of a Single Unit House
Iztok Brinovar, Gregor Srpčič, Zdravko Praunseis, Sebastijan Seme, Bojan Štumberger, Miralem Hadžiselimović, 2019, published scientific conference contribution

Abstract: This article deals with the evaluation of energy efficiency indicators of an older single unit house with the use of "KI energija 2017" software, which is widely used among qualified Slovenian experts authorized to carry out the energy performance assessments and issue an energy performance certificate. The energy performance analysis before and after the implementation of proposed measures has shown significant energy saving potential in renovation of existing buildings.
Keywords: energy efficiency, energy indicators, energy performance, building renovation, CO2 emissions
Published in DKUM: 04.12.2023; Views: 243; Downloads: 8
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6.
Estimation of the Solar Irradiance on Tilted Surface for Different Types of Pyranometers
Sebastijan Seme, Klemen Sredenšek, Iztok Brinovar, Gregor Srpčič, Miralem Hadžiselimović, Bojan Štumberger, 2019, published scientific conference contribution

Abstract: Accurate measurements of solar irradiance are important in many applications such as studying the distribution of received radiation or estimating the final yield of photovoltaic systems This paper deals with evaluation of different types of pyranometers. The primary objective of this paper is to compare two types of pyranometers, with the use of mathematical model for predicting solar radiation on incline surface. The mathematical model shows that both types of pyranometers receives the highest annual average solar radiation with a surface facing 189° south and inclination angle of 44°. The results in this paper show that the deviation between silicon photodiode and thermopile pyranometer mostly occur, due to irregular calibration, frequent cleaning and errors of silicon photodiode pyranometer under overcast sky conditions.
Keywords: pyranometer, solar radiation, azimuth angle, inclination angle, accuracy
Published in DKUM: 04.12.2023; Views: 157; Downloads: 8
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7.
Measurement System for Testing of Electric Drives in Electric Vehicles
Iztok Brinovar, Gregor Srpčič, Sebastijan Seme, Bojan Štumberger, Miralem Hadžiselimović, 2019, published scientific conference contribution

Abstract: This paper deals with the implementation of a measurement system, capable of performing real-time data acquisition and control, and allows the performance analysis of electric drives used for electric vehicle propulsion. For applying the mechanical load on the shaft of the tested motor three different test bench configurations with different power and speed ranges can be used. The main objective of the measurement system is to perform routine performance tests and road simulation tests (in terms of driving cycles) of an electric drive. It provides a research environment for analysis, investigation and study of electric drives and control strategies.
Keywords: measurement system, test bench, electric machines, electric vehicles, permanent magnet synchronous motor
Published in DKUM: 04.12.2023; Views: 188; Downloads: 9
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8.
Efficiency of laser-shaped photovoltaic cells
Ewa Korzeniewska, Mariusz Tomczyk, Łukasz Pietrzak, Miralem Hadžiselimović, Bojan Štumberger, Klemen Sredenšek, Sebastijan Seme, 2020, original scientific article

Abstract: The main aim of this paper is to analyze the influence of laser shaping of the photovoltaic cell based on its efficiency. The authors described both process of the monocrystalline photovoltaic cell manufacturing, its efficiency, and the possibilities of usage in architecture and the process of creating the photovoltaic cells of unconventional shapes by using laser technology. A method for cutting photovoltaic cells using a fiber laser was presented as well as the parameters of the laser cutting process. The described method allows cutting the massively produced silicon cells according to the predetermined trajectory. Using the proposed process parameters, satisfactory cutting edge quality, and negligible impact of the laser beam on changes in the structure of the photovoltaic cell active layers were achieved. In each cycle of structure cutting, only a small part of the material is removed (from 1 to 2 mikro), and depending on the thickness, the process is repeated from 50 to 300 times. It has been shown that the efficiency of the modified cells depends on the ratio of their surface area to the laser cutting line.
Keywords: photovoltaic cells, efficiency, photovoltaic cell modification, laser modification, silicon cells
Published in DKUM: 15.11.2023; Views: 204; Downloads: 11
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9.
Solar photovoltaic tracking systems for electricity generation : a review
Sebastijan Seme, Bojan Štumberger, Miralem Hadžiselimović, Klemen Sredenšek, 2020, review article

Abstract: This paper presents a thorough review of state-of-the-art research and literature in the field of photovoltaic tracking systems for the production of electrical energy. A review of the literature is performed mainly for the field of solar photovoltaic tracking systems, which gives this paper the necessary foundation. Solar systems can be roughly divided into three fields: the generation of thermal energy (solar collectors), the generation of electrical energy (photovoltaic systems), and the generation of electrical energy/thermal energy (hybrid systems). The development of photovoltaic systems began in the mid-19th century, followed shortly by research in the field of tracking systems. With the development of tracking systems, di%erent types of tracking systems, drives, designs, and tracking strategies were also defined. This paper presents a comprehensive overview of photovoltaic tracking systems, as well as the latest studies that have been done in recent years. The review will be supplemented with a factual presentation of the tracking systems used at the Institute of Energy Technology of the University of Maribor.
Keywords: solar energy, photovoltaic tracking system, tracking strategies, drive system, degree of freedom
Published in DKUM: 15.11.2023; Views: 250; Downloads: 14
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10.
Experimental validation of a dynamic photovoltaic/thermal collector model in combination with a thermal energy storage tank
Klemen Sredenšek, Sebastijan Seme, Bojan Štumberger, Miralem Hadžiselimović, Amor Chowdhury, Zdravko Praunseis, 2021, original scientific article

Abstract: The primary objective of this paper is to present a dynamic photovoltaic/thermal collector model in combination with a thermal energy storage tank. The added value of the proposed model is the use and integration of existing dynamic models for describing the entire photovoltaic/thermal system. The presented model was validated using measurements on the experimental system located at the Institute of Energy Technology, Faculty of Energy Technology, University of Maribor. The validation was carried out based on three different weather conditions—sunny, cloudy, and overcast. The validation results were evaluated using the normalized root mean square error and mean absolute percentage error for the temperature and output power of the photovoltaic/thermal collector and the temperature of the thermal energy storage tank. The model results concurred with the measurements, as the average mean absolute percentage error values for the temperature and output power of the photovoltaic/thermal collector and thermal energy storage tank temperature were 5.82%, 1.51%, and 7.58% respectively.
Keywords: photovoltaic/thermal collector, thermal energy storage tank, dynamic modeling, temperature distribution, output power
Published in DKUM: 13.11.2023; Views: 122; Downloads: 9
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