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Opis: This paper deals with the analysis of the cogging torque in a surface-mounted permanent magnet generator in order to determine some techniques to minimize or eliminate the cogging torque. The simulation with finite element method (FEM) was carryout. A four-pole surface-mounted PM generator is investigated in the paper using FEM. The paper analyses the possibilities to reduce this type of torque by producing some asymmetry in the rotor structure. Two types of asymmetry were analysed: the PM pole arc with different widths, and the shifting of the PM. The numerical results obtained in the asymmetrical cases with symmetrical ones were compared and discussed. Finally, some conclusions are highlighted regarding the simulated results.
Ključne besede: cogging torque, electrical machines, FEM analysis, surface-mounted PM generator
Objavljeno v DKUM: 05.12.2023; Ogledov: 41; Prenosov: 2
Celotno besedilo (1,72 MB)
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Opis: This paper deals with pedelecs and e-cars in urban transport systems in selected countries of the Danube region. Within the EU project eGUTS a feasibility study focused on pedelecs and e-cars was made. Country specific information on e-mobility (pedelecs and ecars) was gathered and is briefly presented in chapter 2. In addition, a common SWOT analysis for all selected countries of the Danube region was made and is presented in the conclusion of the paper.
Ključne besede: pedelecs, e-cars, electric vehicles, SWOT analysis, Danube region
Objavljeno v DKUM: 04.12.2023; Ogledov: 50; Prenosov: 4
Celotno besedilo (18,06 MB)

Opis: Agricultural losses due to frost are high in various parts of the world, and in Slovenia, frost damage has frequently occurred in recent decades. Multiple methods for preventing frost damage exist and have been researched more or less extensively. Despite this, frost prevention measures are relatively sparsely used in Slovenia. This article aimed to review and compare active frost prevention technology for a case study of a typical fruit farm in Slovenia, based on a cost-benefit analysis. Most of the active methods require either large capital investment or have a high annual cost. According to our analysis, burning wood, used in Slovenia to battle frost damage in orchards and vineyards, proved to be the most cost-effective method, which is probably why it remains in wide use.
Ključne besede: spring frost, frost protection, cost-benefit analysis, NPV
Objavljeno v DKUM: 04.12.2023; Ogledov: 22; Prenosov: 2
Celotno besedilo (818,18 KB)
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Opis: This article proposes a methodology for the design of double-sided coreless axial flux permanent magnet synchronous machines, which is based on a developed model for calculating the axial component of the magnetic flux density in the middle of the distance between opposite permanent magnets, which also represents the middle of the stator. Values for different geometric parameters represent the input data for the mathematical model in explicit form. The input data are calculated by using a simplified finite element method (FEM), which means that calculations of simplified 3D models are performed. The simplified model consists of two rotor disks with surfacemounted permanent magnets and air between them, instead of stator windings. Such a simplification is possible due to similar values of permeability of the air and copper. For each simplified model of the machine the axial component of the magnetic flux density is analyzed along a line passing through the center of opposite permanent magnets and both rotor disks. Values at the middle of the distance between the opposite permanent magnets are the lowest and are therefore selected for the input data at different stator, rotor disks and permanent magnets (PM) thicknesses. Such input data enable the model to consider the nonlinearity of materials.
Ključne besede: axial flux, analysis, coreless, development, design, explicit form, finite element method, mathematical models, permanent magnet, synchronous
Objavljeno v DKUM: 01.12.2023; Ogledov: 88; Prenosov: 5
Celotno besedilo (2,70 MB)
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Opis: The heterogeneity of welded joints’ microstructure affects their mechanical properties, which can vary significantly in relation to specific weld zones. Given the dimensional limitations of the available test volumes of such material zones, the determination of mechanical properties presents a certain challenge. The paper investigates X welded joint of S690QL1 grade high strength steel (HSS), welded with slightly overmatching filler metal. The experimental work is focused on tensile testing to obtain stress-strain properties, as well as fracture mechanics testing. Considering the aforementioned limitations of the material test volume, tensile testing is carried out with mini tensile specimens (MTS), determining stress-strain curves for each characteristic weld zone. Fracture mechanical testing is carried out to determine the fracture toughness using the characteristic parameters. The experimental investigation is carried out using the single edge notch bend (SENB) specimens located in several characteristic welded joint zones: base metal (BM), heat affected zone (HAZ), and weld metal (WM). Fractographic analysis provides deeper insight into crack behavior in relation to specific weld zones. The numerical simulations are carried out in order to describe the fracture behavior of SENB specimens. Damage initiation and evolution is simulated using the ductile damage material behavior. This paper demonstrates the possibility of experimental and numerical determination of fracture mechanics behavior of characteristic heterogeneous welded joint zones and their influence on crack path growth.
Ključne besede: heterogeneous welded joint, high strength steel, mechanical testing, damage, fracture, mechanical properties, finite element analysis
Objavljeno v DKUM: 30.11.2023; Ogledov: 75; Prenosov: 4
Celotno besedilo (11,25 MB)
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