Conference papers (RICE)
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Item A Comparative Study of Silver Sintering Pastes for Die-Attach Applications: Microstructure, Mechanical Properties, and Reliability(IEEE, 2025) Hlína, Jiří; Hirman, Martin; Michal, David; Rous, Pavel; Janda, Martin; Kulhánek, FilipThis paper is focused on a comparative study of silver sintering pastes for die-attach applications. Three different silver sintering paste from NBETech, Nano-join and Jufeng were used for the study. The quality and reliability of sintered joints between alumina ceramic substrates with printed silver conductive patterns and ceramic mock-up chips were evaluated. A detailed description of the experiments, boxplot diagrams with measured values of mechanical strength, X-ray scans, SEM images and metallographic cross-sections of all tested samples before and after the thermal shock cycling with analysis and recommendations are described in the paper.
Item Voltage Space of Five-Phase Voltage-Source Inverters(IEEE, 2025) Laksar, Jan; Komrska, TomášMultiphase systems offer several advantages over their three-phase counterparts, such as torque enhancement, fault-tolerant operation, etc. In five-phase systems, the inverter output voltage can be increased using the third harmonic, which produces the voltage vector in the x−y plane with additional torque and the zero-sequence, torque-non-producing component. The maximum voltage is obtained with a non-circular trajectory of the voltage vector in the x−y plane, while the machine's optimal operation requires its circular trajectory. The paper focuses on analyzing the space for the voltage increase with respect to the constraints given by the dc-link voltage on the one hand and by the x−y and non-zero voltage component on the other. Theoretical conclusions are verified by simulations and experimental measurements.Item Voltage Zero-Sequence Components in Optimal Control of Five-Phase PMSM Drives(IEEE, 2025) Laksar, Jan; Komrska, Tomáš; Suchý, Ondřej; Šmídl, VáclavThis paper investigates the utilization of the zero-sequence component (ZSC) to increase the voltage and enhance the operation area of five-phase electric drives with permanent magnet synchronous machines (PMSM). Although the ZSC allows reaching higher voltage, its application in multiphase drives is constrained by the usage of x-y planes activated by harmonic components. Since some odd harmonics allow torque enhancement, these planes are typically involved in voltage and current control as part of field-oriented control strategies (FOC) to maximize the torque while minimizing the losses (e.g., Joule losses in the Maximum Torque per Ampere strategy). In five-phase systems, the third harmonic is used for torque enhancement, which affects the maximum value and shape of the resulting voltage waveform across the torque-speed map. Consequently, the space available for ZSC injection is limited and depends on the actual operation point. This paper presents an analysis of how ZSC can be leveraged within these constraints to improve the torque-speed operating map of a five-phase PMSM drive, especially in the field-weakening region. Experimental results obtained on a laboratory five-phase PMSM setup validate the theoretical findings and demonstrate the practical benefits of the proposed approach.Item Sodium-Ion Batteries for Energy Storage Systems: Verification of Properties and Construction of a Small-Scale Battery Storage Unit(IEEE, 2025) Tyrpekl, Miroslav; Zavřel, Martin; Kindl, Vladimír; Frank, Zdeněk; Bednář, BedřichThis paper describes and tests Sodium-Ion batteries, a new type of battery that is beginning to be supplied for industrial use. The aim of the work is to verify the battery's properties in order to develop and design a BMS (Battery Management System) unit capable of operating with this type of battery. The tested properties were subsequently implemented into the BMS unit. A test stand was built using the BMS unit, which features both active and passive balancing. Compared to lithium-based batteries, sodium-ion batteries promise higher safety and lower cost, making them a strong candidate for future large-scale energy storage solutions.Item A New Hybrid High-Gain Bidirectional Converter for Energy Storage Applications(IEEE, 2025) Bhajana, V. V. Subrahmanya Kumar; Drábek, Pavel; Biswal, PravatThis paper proposes a new hybrid high-gain bidirectional DC-DC converter for energy storage system applications. The voltage multiplier cell (VMC) in the proposed topology is modified with one additional switch to provide a discharge path for the multiplier capacitor, and another switch is incorporated to obtain buck mode operation. The proposed converter offers two significant features: in boost mode, the voltage conversion ratio is enhanced through a voltage multiplier cell, and in buck mode, output power is delivered using only a single switch. The main advantages of the proposed topology include a reduced total number of components, lower voltage stresses, and operation of all switches with minimal duty ratios. This paper presents the operating principles, gain analysis, and simulation results for a 12 V/370 V converter system.Item Výuka rozšířené reality na elektrotechnické fakultě – spojení teorie a praxe v průmyslových aplikacích(Vysoká škola polytechnická Jihlava, 2025) Kropík, Petr; Šroubová, LenkaV rámci předmětu Průmyslové využití virtuální a rozšířené reality garantovaném Katedrou elektrotechniky a počítačového modelování se studentky a studenti seznamují s principy aplikace virtuální a smíšené reality v kombinaci s objekty reálného světa v oblasti lektrotechnického průmyslu. Studující se musí hlouběji zaměřit na pochopení tvorby aplikací pomocí programovacích technik a využití vývojových nástrojů pro vizualizaci smíšené reality. Na mobilních zařízeních studující zobrazují reálné výsledky skutečných prací z jiných projektových předmětů. Motivace je udržována prostřednictvím skupinových semestrálních úloh, které podněcují aktivní zapojení a zájem o danou problematiku.
Item Achievement of Fast Rise Time Pulses Using Conventional Impulse Generator(IEEE, 2025) Krejnická, Tereza; Benešová, Zdeňka; Haller, Rainer; Martínek, Petr; Müllerová, EvaThe increased use of power electronics devices in electrical systems as well as industrial drives leads, for applied electrical machines, to a special kind of electrical stress. Besides a lot of other parameters that electrical stress may be characterized by so-called steep front pulses with rise time much lower than 1μs. Therefore, for quality assessment of components of electrical machines and, in particular, formwound stator coils of electrical motors, related standards content testing procedure by impulse testing with front times less than 0.3μs. The achievement of such pulse parameter using a commercially available impulse generator requires some special measures which are described in detail in the paper. As expected, the main impact on achieving the required value of front time is given by the resulting circuit inductivity, which must be reduced drastically. It was shown that the reducing of the circuit inductivity is not only dependent on applied performance of test generator, but also on the local arrangement of sample under test. The practical measures were confirmed by simulation of test circuit arrangements using appropriate software tools like ATP and MATLAB.Item Testing of Some Performance of Insulating System with Biodegradable Ester(IEEE, 2025) Trnka, Pavel; Hornak, Jaroslav; Michal, Ondřej; Mokrá, Zdislava; Hardoň, Štefan; Kúdelčík, Jozef; Frána, Zdeněk; Leffler, Jan; Tomášková, TetjanaThe comparative study of the aging processes of cellulose paper and Nomex® paper in biodegradable insulating fluids in various condition is of importance to the electrical engineering field, particularly in the development and maintenance of sustainable high-voltage insulation systems. This research investigates the aging behavior of these insulation materials when immersed in eco-friendly, biodegradable fluids, aiming to evaluate their longevity and performance under various operational stress. Electrical insulating systems based on synthetic, natural and mineral oil are compared when solid part is created by cellulose and aramid paper.Item Technology of Custom Designed Mono-Si Photovoltaic Cells for Specific Purposes and Energy Communities(Springer Science and Business Media Deutschland GmbH, 2025) Bělík, MilanThis paper presents a new approach to recycling used monocrystalline Si photovoltaic cells. It focuses on creating custom designs for specific applications and energy communities. The target is to develop cheap and efficient technology to manufacture custom designed PV cells applicable for various specific purposes and for usage in energy communities. The idea originates from possible recycling of used or defective monocrystalline silicon photovoltaic modules. The modules could be disassembled to components and these structures could be further reused. The paper focuses on usage of disassembled cells. Cells with age of several years cannot compete in term of efficiency with cells produced with modern technology. On the other side these cells have been already manufactured and the environment has been already stressed with their carbon footprint. The proposed technology aims to reduce environmental impact while meeting the aesthetic and functional demands of modern consumers. It is important to understand that actual photovoltaic market is very different from the situation 10 or 5 years ago. Significant number of customers focuses not on the power generation or its efficiency itself but on other features of photovoltaic systems, namely design. New design ways and approaches have been introduced during recent seasons. The main task of this paper is to introduce cheap and efficient technology of custom designed mono-Si photovoltaic cells from recycled PV modules. These cells can offer variable design features important for specific new group of private customers and energy communities.Item Photovoltaic System Designing for Power Supply of School in Ukrainian Conditions(Springer Science and Business Media Deutschland GmbH, 2025) Rubanenko, OlenaPhotovoltaic system in Ukraine is viewed not only as a business opportunity, but also as a way to diversify energy supply and a component of energy safety. Stability and efficiency of Ukraine's energy sector primarily in the development of distributed generation, including green energy. Case-study projects of designed PV-system are presented in paper. Digital Twins of different type of PV- systems designing with usage relevant software is shown.Item Timepix4: Power Supply Topology Optimization(IEEE, 2025) Růžička, Ondřej; Burian, Petr; Kulhánek, Tomáš; Zich, JanThis paper describes the design of a power management system for the Timepix4 readout chip. The Timepix4, the latest generation of the Timepix family developed within the MEDIPIX collaboration at CERN, is a powerful readout chip for particle pixel detectors. It offers enhanced resolution with a matrix of 512×448 pixels and excellent timing performance with 195 ps time binning. However, this high performance comes with strict requirements for power supply stability and low-noise operation. The authors discuss these requirements in detail and propose several candidate solutions for optimal powering of the chip. Two of these solutions were practically implemented and tested. The evaluation is based on measurements of electrical parameters as well as the impact of the proposed power supply concepts on the actual performance of the detector.Item A Compact and Wideband Wilkinson Power Divider Using Lowpass Microstrip Filters(IEEE, 2023) Jalalian, Hesam; Al-Anbagi, Haidar N.; Jahanbakhshi, Maryam; Almtrod, Abdalghfor Abdalghfar APower dividers are the most important tools in microwave systems such as mixers, frequency multipliers, and feeding networks in antennas. So far, in designing power dividers, various methods have been used to reduce the size and eliminate unwanted harmonics. In this paper, using a resonator structure and low pass filter, a Wilkinson power divider with I-shaped structure is designed, simulated, and fabricated. According to the results of the simulation, this structure has 6-harmonic elimination. The size of the designed power divider, due to the use of resonators, has dimensions of 0.06 × 0.07 λg2, which reflects a size reduction of 65% and indicates one of the advantages of this divider. The guided wavelength at the working frequency of the resonator is calculated at 0.97 GHz. This structure also has a relative working bandwidth of 42%, which indicates its wide operation band. The isolation value is −31 dB, which is another benefit of this power divider. This divider has been built and measured on the Rt-duroid 5880 substrate, where the responses from the simulation and real implementation have good match.Item Development of a Low Budget Solar Simulator for Testing the Solar Radiation Effects(IEEE, 2025) Hirman, Martin; Skarda, Jakub; Čengery, Jiří; Kučera, Tomáš; Steiner, FrantišekThis paper presents the development of a low-cost solar simulator designed for testing the effects of solar radiation on various materials and photovoltaic cells. The simulator aims to replicate the solar spectrum identified as AM1.5G, adhering to the IEC 60068-2-5 standard, while significantly reducing acquisition costs compared to commercially available devices. The construction utilizes light-emitting diodes (LEDs) as the primary light source due to their energy efficiency, long lifespan, and spectral adjustability. An optical simulation was conducted using Ansys SPEOS software to optimize the LED arrangement and ensure uniform spectral irradiance across a test area of 200mm×200 mm. The results indicate that while the simulator meets several spectral requirements, further modifications are necessary to improve radiation intensity and homogeneity. This research contributes to the accessibility of solar testing technologies for educational and research institutions with limited budgets.Item Reusing SMD Components on E-textiles: An Ageing Study by Combination of Corrosive Gases and Washing(IEEE, 2025) Hirman, Martin; Navrátil, Jiří; Benešová, Andrea; Steiner, FrantišekThe growing demand for sustainable practices in the electronics industry has led to the exploration of circular economy principles, particularly in e-textiles. This study investigates the feasibility of reusing surface-mount device (SMD) components integrated into conductive textile ribbons under conditions simulating real-life degradation. Using accelerated aging tests involving exposure to corrosive gases and washing cycles, we evaluated the durability of electrical connections and conductive paths. Results show that SMD components can be reused across multiple life cycles with minimal performance loss, while conductive ribbons exhibit degradation primarily during washing. Protective measures, such as seam-sealing adhesive tape, were effective against environmental pollutants but less so against detergent infiltration during washing. A novel remanufacturing process was employed to extract, clean, and reattach SMD components, demonstrating their viability for reuse without compromising quality. This research highlights the potential for sustainable etextile manufacturing by enabling component reuse and reducing electronic waste.Item Acoustic Monitoring of Partial Discharges: Differentiating Corona and Surface Discharges Using Ultrasonic Methods(IEEE, 2025) Pihera, Josef; Tureček, Oldřich; Balvín, Ondřej; Řeboun, JanThe measurement and monitoring of partial discharges (PD) have become increasingly important due to the rapid rise of new technologies that increase the frequency of PD occurrences in electrical equipment, where such phenomena were previously absent or limited. This effect directly impacts the lifespan and reliability of devices, raising the need for timely diagnostics for their detection. This study focuses on the detection of partial discharges using acoustic methods, with particular attention given to the use of ultrasonic microphones. The aim of this work was to analyze the acoustic emission signals generated by partial discharges, such as corona and surface discharges, and evaluate how their frequency spectra can be used to distinguish between these types of discharges.For the measurement of partial discharges, an ultrasonic microphone was used to record the acoustic signals generated by discharges in the tested materials. The signal was then processed using FFT analysis. This process provides a detailed overview of the frequency components of the acoustic emissions, which are characteristic of various types of partial discharges, such as corona and surface discharges for different materials. Key frequency bands were identified that correlate with the intensity and type of discharges, enabling their effective differentiation.Item Soutěže a kreativní úlohy v programování – inovace v zadávání úloh s nástupem umělé inteligence(Vysoká škola polytechnická Jihlava, 2025) Šroubová, Lenka; Kropík, PetrV předmětech Katedry elektrotechniky a počítačového modelování týkajících se programování, práce s výpočetními systémy a informačních technologií dlouhodobě vyučujeme s využitím autotestů, autodiagnostických testů i řádných testů. Využíváme k tomu systém Moodle. S nástupem umělé inteligence je třeba formulovat úlohy tak, aby student nemohl snadno najít odpověď. Prioritou začíná být, aby student vygenerovaný kód pochopil, porozuměl mu a upravil ho podle zadání. Samotné zadání příkladů z programování je nutno koncipovat kombinováním nejen reálných příkladů z praxe a úlohpropojených s jinými teoretickými předměty, ale i smyšlených příběhů. Motivace pro řešení úkolů je udržována formou semestrálních soutěží.Item Diagnostický systém pro prediktivní údržbu elektrických strojů v rámci správy aktiv(Západočeská univerzita v Plzni, 2025) Leffler, Jan; Mokrá, Zdislava; Sláma, Pavel; Frána, Zdeněk; Trnka, PavelTento příspěvek představuje přístup založený na univerzálním, modulárním, škálovatelném a nákladově poměrně efektivním systému, který byl vyvinut speciálně pro menší provozy s nízkonapěťovými až vysokonapěťovými elektrickými zařízeními a stroji. Navrhované komplexní řešení umožňuje lokální, autonomní odhad zbývající životnosti i pravděpodobnosti poruchy v reálném čase prostřednictvím využití relevantních a originálních modelů propojených s příslušnými provozními diagnostickými signály. Tento systém tak nabízí možnost zvýšit provozní spolehlivost aktiv, snížit náklady na údržbu, řídit stárnutí a prodloužit životnost aktiv v rámci strategie prediktivní údržby.Item Behavior of Printed Conductive Structures Under Cyclic Load Realized by Direct-Write on a Textile Substrate(IEEE, 2024) Janda, Martin; Pretl, Silvan; Řeboun, JanIn this work, the stretchability of conductive tracks realized by Direct-Write on a thermoplastic polyurethane foil and laminated onto a textile, is analyzed. Samples of printed tracks are subjected to the mechanical cyclic stress test, and their electrical resistance is measured. Also, the mechanical properties of polyurethane foil as well as foil laminated onto a textile are measured. Results show, that the mechanical properties of a substrate play an important role in the electrical behavior of printed tracks, and therefore such stretchable systems should be always analyzed as a combination of its parts rather than just in terms of conductor properties.Item Comparison of Polarization Phenomena and Changes in Relative Permittivity in Mineral- and Ester-Based Nanofluids(IEEE, 2025) Mokrá, Zdislava; Trnka, Pavel; Michal, Ondřej; Hornak, Jaroslav; Sláma, PavelTwo different phenomena were observed in nanofluids with different oil-based fluids. While the relative permittivity increases in mineral oil-based oxide nanofluids, the opposite effect is seen in ester nanofluids. This paper describes the relaxation times and polarizations in pure oil samples and nanofluids, using Havriliak-Negami formula, a mathematical explanation of this phenomenon is attempted. An experiment was conducted where pure samples of the mineral oil Nynas Lyra, the natural ester rapeseed oil, and synthetic ester oil MIDEL 7131, and then their nanofluids with SiO2 additive were measured. The measurements were carried out using Broadband dielectric spectroscopy as a function of frequency and temperature.Item The fast neutron fluence and the activation monitor activity calculations using fine multigroup and continuous nuclear data(EDP Sciences, 2024) Lovecký, Martin; Tušlová, Pavlína; Smutný, VladimírThe fast neutron fluence and the activation monitor activities are routinely calculated with TORT deterministic code and BUGLE-B7 nuclear data library with 47 broad energy groups. The objective of the paper is to analyse options to improve reactor dosimetry transport calculations. There are two paths to improve reactor dosimetry calculations. Increasing geometry, angular and energy mesh size is applicable for TORT code while using newer nuclei data libraries is relevant for both deterministic and Monte Carlo codes. Two new calculation options (improved TORT and Monte Carlo MCNP6) were compared with the standard TORT calculation for VVER-440 Dukovany Unit 3 Cycle 31. The fast neutron fluence with 0.5 MeV threshold as well as activity of Fe, Ni, Ti, Cu, Mn and Nb monitors were evaluated. Standard TORT calculations were improved from S16P3 to S30P3 with three times finer axial mesh size, 120° core symmetry r-9 mesh size with 0.5° step and fine multigroup libraries VITAMIN-B7 with 199 neutron energy groups and ENDF/B-VII.1 with 200 neutron energy groups. Both EMDF/B and IRDFF activation cross sections were used The drawback of expanded mesh size is raised calculation runtime since TORT deterministic code is not parallelized and one calculation can require multiple weeks of CPU time An alternative option of using MCNP6 Monte Carlo code with continuous ENDF/B-VE.1 nuclear data with detailed 3-D geometry and pin-wise effective neutron source prepared by MOBY-DICK diffusion code reactor analysis was explored. It was found that using finer mesh size affects reactor dosimetry tallies less than the choice of nuclear data library. BUGLE-B7 and VITAMIN-B7 produce results typically within 1% difference. ENDF/B-VII.1 calculations with 200 neutron energy groups with TORT code are even in better agreement with MCNP6 calculations with continuous nuclear data libraries The largest differences of around 2% were observed between VITAMIN-B7 library based on ENDF/B-WO nuclear data and ENDF/B-VII.l library. Nuclear data library has larger impact on the results with up to 7 % difference between all 0.5 MeV fast neutron fluence calculations. The largest impact of nuclear data was observed for Mn(n,2n) monitor.
