Artykuł poświęcony jest opracowaniu i badaniom systemu sterowania siłą docisku elektrod w zgrzewarce rezystancyjnej. Jest to rozwiązanie nowatorskie, mogące zastąpić stosowane dotąd systemy pneumatyczne lub serwomechaniczne. Zaproponowany w artykule system bazuje na systemie czterech elektromagnesów – dwóch przyciągających i dwóch powrotnych, czterokanałowym układzie energoelektronicznym zasilania oraz na wspólnym układzie sterowania, pozwalającym na równoważenie sił między elektromagnesami.

For precise angular characterization of high-temperature superconducting (HTS) tapes, creating a stable and uniform magnetic field that allows full 360 degrees sample rotation poses specific design and implementation challenges. This work introduces a compact cylindrical Halbach array composed of permanent magnets, designed to generate a uniform magnetic flux density up to 350 mT. The system is dedicated to angular-dependent measurements of the critical current I-c in HTS tapes. The Halbach configuration was optimized using finite element method (FEM) simulations to maximize field uniformity in the measurement region The experimental setup was fabricated using additive manufacturing and integrates the Halbach array with a four-probe measurement system operating at 77 K. The mechanical design ensures precise, continuous rotation of the superconducting sample within a cryogenic environment without degrading field symmetry. Angular dependence of critical current I-c was experimentally characterized and compared with results obtained using conventional solenoidal magnets and established analytical models. The results confirm that the Halbach array provides sufficient magnetic field uniformity for reliable I-c(theta) determination while significantly reducing system cost, power demand, and cooling complexity. The maximum field of approximately 0.35 T limits the applicability of the device to low-and moderate-field measurements, making it particularly suitable for laboratory-scale testing and industrial quality control of HTS conductors.

The effect of pulse welding current (DC, 1 kHz) on the progression of projection welding process of nuts was analysed. The study involved a comparative analysis using identical average value for pulsed DC current with continuous direct current (DCc), which is commonly used in conventional mode. The analysis was conducted for nuts featuring four trapezoidal projections, made of grade 10B21 steel (AISI1017-SORPAS library), with a projection height of 1.2 mm and an initial contact area between the projection and the sheet metal of 7.8 mm2. The second welded component was a 3.0 mm thick DC04 sheet metal. Numerical analyses in both cases were conducted using the SORPAS™ software. The characteristic parameters evaluated were weld strength, volume of melted material (in both the sheet and the projection), area of molten material in the contact region, welding energy, and average welding current. The results of the numerical calculations were verified experimentally. The study demonstrated the beneficial effect of pulsed welding current (DC, 1 kHz) on weld quality, particularly in terms of improved strength. It is possible to both reduce welding time and increase weld strength for pulsed DC welding. With comparable weld strength, welding time can be reduced by over 30

The paper is aimed at the analysis of the influence of the welding current source (type-AC/DC) and its connection to the electrical grid on the quality of the resistance projection welding process (nuts/bolds). The investigation is based on FEM-SORPAS analysis. The relationship between (i) weld strength, (ii) the area of the melted material in the contact area of the welded elements, i.e., projection—sheet metal, and (iii) the volume of the melted material in the welding area is described in relation to the type of the welding current (AC/DC). Selected FEM calculations were referred to experimental results. In the second step, the influence of a source type and connection method on the decrease of the welding current was determined by a circuit modelling using the FALSTAD simulation environment. The obtained results show that the voltage drop and current decrease caused by the line connections and converter structure significantly reduce the strength of the joint. For nominal parameters, i.e., welding current source (type-AC/DC), the FEM calculation results were verified experimentally. Metallographic examinations of welded joints (AC/DC) were performed and compared with the temperature distribution in the welding area for FEM.

The paper is devoted to analysis of power losses in a resistance welding machine including supplying system and examination of welding conditions of the welding machine current in a case of synchronous (simultaneous) operation of multiple welding machines, i.e., during the conduction of welding current. Analysis of the most important contributors of power losses generated on the current path between a power source and the welded joint is carried out. The analysis is carried out for a DC (direct current) welding machine with power electronics inverter. AC (alternating current) welding machines are also taken into account. The analysis is divided in two parts. The first one is the analysis of single welding machine operation, while in the second part, coexistence (mutual operation) of two synchronous welding machines is considered. The analysis is based on results of numerical and experimental investigations. The first one is focused on calculation of power losses in the energy path (including a Sankey type power loss distribution diagrams), and the second one is based on experimental tests carried out to determine the diameter of the weld nugget and the strength of the joints, for cases of reducing the welding current. An example of simultaneous operation of welding machines was presented and discussed. The percentage voltage drops and power losses in the entire power supply path of the resistance welder are shown. The analysis carried out is extremely important from this point quality of welded joints.

The pressing need to switch to sustainable modes of transportation is brought on by concerns over air pollution, environmental degradation, and energy security. Traditional internal combustion engine vehicles (ICEVs) are starting to give way to different electric vehicles (EVs), including fuel cell electric vehicles (FCEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs) which are sustainable modes of transportation. Power electronics systems are essential to the success of these technologies because they provide effective energy conversion, control, and management of power in electric drivetrains and charging infrastructure. This study examines some important applications of power electronics systems in environmentally friendly transportation.

Modern educational methods ensuring individualized approach for student's expectations, based on Project/Problem based Learning realized recently at the Silesian University of Technology under Initiative of Excellence - Research University are described in the paper. Three examples of recently realized projects, focused on area of power electronics, electrical drives are presented.

The paper focuses on the description, design, construction of a prototype and examination of the test bench for characterization of superconducting tapes operating at low magnetic fields. The test bench is based on a rotating cylinder containing permanent magnets and producing homogeneous magnetic field in the center, where a superconducting tape is located. The 3D printing additive manufacturing technology is used for construction of the test bench. Designed measuring device allows for fast and easy characterization of angular dependence of the critical current density on external magnetic field of examined tape. The test bench is dedicated to examination mostly for HTS tapes (1G tapes made as silver matrix with filaments and 2G tapes made as coated conductors), which is leading superconducting tapes technology. The description presented in the paper contain description of the idea of tool supported by FEM analysis, description of manufacturing and selected results of tests. Problem of scalability of results is also discussed in the paper.

The paper is focused on analysis of properties of power electronic transformer operating at resistance welding machine with frequency of 10 kHz and its influence on commutation process in output rectifier. Recently, the most popular resistance welding systems in industrial processes are based on DC welding machines with power electronic inverters. Such systems has numerous advantages for resistance welding, but because of very high welding current, power electronic converters are very sensitive on leakage inductance of the transformer. So, the output transformer, having output current at a level of 10 kA or more, needs special design to minimize the leakage inductance. Analysis in the paper is based on existing resistance welding system and shows in qualitative and quantitative way influence of leakage inductance on the output current of the welding machine. Also some technological aspects are discussed.

An industry-wide transformation towards sustainable mobility is being heralded by the rise in battery electric vehicles (BEVs). However, there are issues with vehicle interoperability, user convenience, and manufacturing efficiency due to the variety of energy storage technologies. With an emphasis on the traction battery pack's structure, vehicle model compatibility, and battery swap ease of use, this article promotes standardization of essential components of BEV energy storage systems. In to facilitate interchangeability and compatibility amongst BEV models, it suggest a standardized approach to pack structure that includes common form factors, interface standards, and mounting mechanisms. The importance of interoperability in promoting smooth integration and communication between BEVs made by different manufacturers is covered. Finally, the paper stress that industry stakeholders must work together to advance standardization initiatives. To ensure alignment with changing market needs and technical improvements, it offers ideas for automakers, regulatory bodies, and infrastructure providers on how to efficiently deploy and improve standardized solutions. The goal is to accelerate the shift to sustainable mobility, foster interoperability, and uncover efficiency improvements in BEV energy storage systems through the advancement of standardization.

Education of engineers entering to Hi-Tech industry requires application of novel methods and approaches, ensuring understanding not only principles of knowledge, but also organization of designing process and modern form of team collaboration. This approach is present in education by Project Based Learning (PBL). Recent PBL-based activities performed by students in Lab of Power Electronics at the Silesian University of Technology, shows that this approach brings numerous benefits. PBL as a form of practical education ensure individual approach to student’s expectations and allows to include results of students’ investigation to a research conducted by academic staff. Presented results of realized projects show that the student’s research can be devoted both, to solve new research problems and develop devices and demonstrators dedicated for educational purposes. Idea of Project Based Learning, expected outcomes, range of performed activities and examples of results are presented.

Modern power systems are affected by current harmonics. The high-order harmonics may result in overheating of the power system and lifetime reduction. Hence, the most novel power systems are equipped with three-phase line chokes. However, power losses generated in three-phase chokes result in a temperature increase within the choke. Most of the commercially available three-phase chokes are equipped with a passive air-based cooling solution. Such a solution results in an increase in the overall size of the device as well as an increase in the manufacturing costs. The water-cooling plates were installed in the commercial three-phase and the cooling performance of the air-and water-based cooling systems were experimentally compared. The chokes were analyzed at the RMS currents that corresponded to 100%, 75% and 50% of the nominal losses of the device. The temperature of the chokes was monitored with the thermocouples and precise IR camera. The comparison of the thermal results showed that the water-cooled choke outperformed the air-cooled unit. The core temperature of the device was reduced from approximately 110 degrees C to approximately 26 degrees C for the water-cooled solution compared to the air-cooled one. The temperature distribution in the windings was comparable for both solutions. The highest measured temperature exceeded 100 degrees C for both cooling solutions. The experimental results presented in this study can be used for further modification of the water-cooling system. Especially, in terms of the water panels' shape, position and water inlet configuration. Such modifications should lead to further reduction of the device temperature, material and manufacturing costs.

The article presents a theoretical and measurement analysis of the angular dependence of the critical current in high-temperature superconducting (HTS) tapes of the first generation. The research focused on the impact of the value and direction of the magnetic field on critical currents. The paper also describes the construction and operation of a specially designed test station using neodymium magnets in the Halbach configuration, which allows for precise measurements and characterization of HTS tapes. The results confirmed the consistency with the Kim model and contributed to the development of a critical current density model that can be used in further computer simulations.

Superconducting technology based on materials with unique properties in the range of the transport current and interaction with a magnetic field has a chance for wide development in the field of electrical and energy applications. Superconductivity, although known for over 110 years, requires a strategic and long -term approach to the implementation of this advanced, but also sensitive to operating conditions, technology. The article summaries a roadmap for the development of superconductivity in the field of electrical engineering, outlined as part of the work of the Section of Electrotechnical Materials and Technologies of the Electrotechnical Committee, Polish Academy of Sciences.

Ensuring the energy transition in order to decrease CO2 and volatile organic compounds emissions and improve the efficiency of energy processes requires the development of advanced materials and technologies for the electrical energy sector. The article reviews superconducting materials, functional nanomaterials used in the power industry mainly due to their magnetic, electrical, optical, and dielectric properties and the thin layers of amorphous carbon nitride, which properties make them an important material from the point of view of environmental protection, optoelectronic, photovoltaic and energy storage. The superconductivity-based technologies, material processing, and thermal and nonthermal plasma generation have been reviewed as technologies that can be a solution to chosen problems in the electrical energy sector and environment. The study explains directly both—the basics and application potential of low and high-temperature superconductors as well as peculiarities of the related manufacturing technologies for Roebel cables, 1G and 2G HTS tapes, and superconductor coil systems. Among the superconducting materials, particular attention was paid to the magnesium di-boride MgB2 and its potential applications in the power industry. The benefits of the use of carbon films with amorphous structures in electronics, sensing technologies, solar cells, FETs, and memory devices were discussed. The article provides the information about most interesting, from the R&D point of view, groups of materials for PV applications. It summarises the advantages and disadvantages of their use regarding commercial requirements such as efficiency, lifetime, light absorption, impact on the environment, costs of production, and weather dependency. Silicon processing, inkjet printing, vacuum deposition, and evaporation technologies that allow obtaining improved and strengthened materials for solar cell manufacturing are also described. In the case of the widely developed plasma generation field, waste-to-hydrogen technology including both thermal and non-thermal plasma techniques has been discussed. The review aims to draw attention to the problems faced by the modern power industry and to encourage research in this area because many of these problems can only be solved within the framework of interdisciplinary and international cooperation.

Nowadays, as an alternative to conventional mineral oils used for cooling in distribution transformers, environment-friendly ester oils are getting more attention. For this reason, the main objective of this work was to compare the cooling efficiency of both types of coolants in the medium-power distribution transformer under different ambient conditions. It was conducted by the development of a validated coupled numerical model that included all thermal, flow, and electromagnetic phenomena. Moreover, all the calculations were carried out for mineral, synthetic, and natural ester oils. As a result, the coupled computational fluid dynamics (CFD) model determined the hot-spot temperature within the transformer tank at three ambient temperatures on the basis of the local distribution of the power losses in windings and core that were delivered from the electromagnetic submodel. The investigated ambient temperatures of $- 10\,\,^{\circ} \text{C}$ , $20 ^{\circ} \text{C}$ , and $30 ^{\circ} \text{C}$ represented summertime and wintertime for two climate conditions. The numerical results also showed a satisfactory agreement with the measured temperature values recorded in the analyzed distribution transformer with mineral oil. In addition, it was presented that the highest hot-spot temperature of $94.6 ^{\circ} \text{C}$ was reached for the case of natural ester oil at $30 ^{\circ} \text{C}$ of the ambient temperature representing maximum monthly averaged Argentinian climate conditions. In these conditions, the hot-spot temperature transformer with mineral oil was only 1.6 K lower. Furthermore, one of the investigated synthetic ester oils allowed to reach even better cooling effectiveness than in the case of mineral oil. Therefore, more effective cooling connected with environment-friendly characteristics encourages to use of biodegradable oils for distribution transformers.

The principle of Digital Twin (DT) is to create a connection between a physical asset and its corresponding virtual twin established by generating real-time data using sensors. DT can be used for real-time condition monitoring, fault detection, optimization, prognosis, and lifetime prediction. This paper proposes the application of a DT service unit for an electric vehicle (EV) induction motor (IM) fault detection. IM stator inter-turn short circuit fault is used as a study case to highlight the DT service unit function. Such a fault is considered one of the most prevalent possible IM failures. Based on real-time measurements, Linux Robot Operation System (ROS) simulates IM’s specific behavior in case of unbalanced stator currents and notifies about possible fault appearance and propagation. The obtained results from DT allow adding additional services that consider another failure, and as a result, improve physical entity reliability.