Browsing by Author "Sahin, C"

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    Design and Finite Element Analysis of a 6/4 Pole Multi-Layer Fully Pitched Switched Reluctance Motor to Reduce Torque Ripple
    Sahin, C; Basaran, S
    -In this study, the design and analysis of multi-layer fully pitched winding switched reluctance motor (MFP-SRM) for general use (submersible pump, electric vehicles, etc.) have been performed. It is seen that the multi-layer switched reluctance motor (SRM) has higher output power when compared to the single-layer SRM. In multi-layer SRM, the motors in the layers are electromagnetically independent of each other although they are identically the same motors with the same characteristics in terms of performance and geometry. Each layer of the MFP-SRM which is designed in this study consists of a 6/4 pole fully pitched SRM (FP-SRM) and these motors are magnetically independent of each other. In the MFP-SRM, which is designed as a double layer, there is a 15 degrees phase difference between the rotor position angles and torque profile curves of each layer. With the phase difference that changes depending on the number of layers, each layer contributes to the total torque production of the profile, ensuring a smooth profile. According to the results of the 3D FEM analysis, it is seen that the proposed multi-layer motor structure has high starting torque and low torque ripple properties. In the analysis carried out in the range of 3-15 Amperes, the torque ripple of the traditional FP-SRM varies between 31.99% and 38.19%, while the torque ripple of the proposed MFP-SRM only varies between 3.23% and 7.11%.
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    Life performance prediction of natural gas combined cycle power plant with intelligent algorithms
    Karaçor, M; Uysal, A; Mamur, H; Sen, G; Nil, M; Bilgin, MZ; Dogan, H; Sahin, C
    The efficient use of a system is enabled with the life performance estimations. Thus, the effective use of underground resources is realized especially natural gas. Based on this, life performance models were generated to aim of improving the efficient use of energy for a combined cycle power plant (CCPP) of 243 MW installed in Izmir, Turkey by using fuzzy logic (FL) and artificial neural network (ANN) in this study. Therefore, output power estimations were carried out. Depending on the developed models, an estimation of the energy that the CCPP can produce and provide to the interconnected system in the following years has been made. According to the obtained results, the error prediction rates of FL and ANN models were determined. It was found that while the energy relative error estimation value that can be produced between the years calculated in modeling using FL varies between 0.59% and 3.54%, this value was found to vary between 0.001% and 0.84% in modeling using ANN. This result shows that the ANN model is more suitable for the life performance estimations of such a nonlinear system.
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    Design and fabrication of an outer rotor permanent magnet synchronous generator with fractional winding for micro-wind turbines
    Mamur, H; Sahin, C; Karaçor, M; Bhuiyan, MRA
    Permanent magnet synchronous generators (PMSGs) have been widely used in micro-wind turbines (MWTs) for direct-drive applications. The generating maximum power from the PMSGs used in the MWTs is desired. However, cogging torque (CT) and design form of the PMSGs prevent this. Therefore, various methods are applied to reduce the CT of PMSGs in the literature. Some of them are inapplicable and some are the ones that cause power loss. In this study, to overcome the expressed causes, a new design, fabrication, and application of an outer rotor PMSG with fractional winding having a slot-pole combination technique for MWTs have been suggested, designed, and implemented on an MWT. As a result of the new design combination of +/- 1 or +/- 2 between the numbers of stator slot (N-S) and the number of pole-pairs (2p), the ratio of the CT value to the nominal torque value in the new prototyped outer rotor PMSG was found as 6.25%. Finally, the operating power can generate 1029 W through the prototype PMSG with fractional winding having a slot-pole combination technique integrated into the direct-drive MWT system.
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    Principle, design and analysis of a novel axial flux switched reluctance machine with fully pitched winding structure
    Sahin, C; Karacor, M
    In this study, the fully pitched axial flux switched reluctance machine (FP-AFSRM), which is a new configuration in the literature, was designed and 3D magnetostatic analyses were performed. The focus of the study is to produce higher torque density by simply changing the winding structure. Conventional SRMs are also known as short pitched SRM (SPSRM) since they have a short pitched winding structure. Fully pitched SRMs (FPSRMs) produce higher torque compared to SPSRMs with the mutual coupling effect between phases due to their fully pitched winding structure. In parallel with that, especially for electric vehicles, axial designs have increased gradually instead of radial design of electrical machines. For this purpose, the FP-AFSRM structure was proposed by combining axial design and fully pitched winding structure. The proposed FP-AFSRM model achieved up to 15.07% higher torque density than the basic SP-AFSRM model at different currents and equal copper losses. The proposed FP-AFSRM can be considered as an important alternative machine, especially for electric vehicle technologies and different technological fields, with the advantages of the high torque density and axial geometric structure.
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    Comparison of Aluminum and Copper Winding Materials for Switched Reluctance Machines with Finite Element Analysis
    Sahin, C
    Today, with the decrease in fossil fuel reserves, interest in electric vehicles has grown. Undoubtedly, electric machines are one of the most important parts of electric vehicles. Studies on electrical machines directly affect vehicle performance. Since the electrical machine used is mounted on the vehicle, reducing the total weight without changing the output power will positively affect the overall performance of the vehicle. The windings used to create the magnetic field in electrical machines are made of copper. Electrical machinery manufacturers try to use completely different materials instead of copper or partially reduce its use. At this point, aluminum emerges as an attractive material for various manufacturers. This study analyzed the winding structure of a switched reluctance machine (SRM) proposed for an electric vehicle by using copper and aluminum at an equivalent resistance value, the results of which were compared. As a result of a 2D finite element analysis, it was observed that the machine's output performance is largely kept when aluminum is used instead of copper for the winding. It was also observed that the aluminum total winding weight decreased by 43,40% compared to that of copper.
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    Salivary inflammatory burden in pre- and postmenopausal women: Associations with body mass index, patient-reported health, serum cytokines, and periodontal parameters
    Yakar, N; Bostanci, N; Özdemir, G; Atmaca, H; Türedi, A; Sahin, C; Köse, T; Emingil, G
    Background: The decline of estrogen levels during menopause impacts weight, mood, and overall health, both orally and systemically. This study assessed salivary levels of tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), IL-10, and IL-7 in postmenopausal (PMW) and regularly menstruating premenopausal (RMPW) women, while considering serum cytokine levels, body mass index (BMI), periodontal health, and self-reported physical and emotional well-being.Methods: In this study, 75 PMW and 71 RMPW were included. Clinical and periodontal parameters were evaluated, and perceived health was assessed with the Women's Health Questionnaire (WHQ). Cytokine levels in both saliva and serum were quantified by enzyme-linked immunosorbent assay (ELISA). Covariate evaluations of salivary cytokines were conducted using hierarchical linear regression modeling.Results: Cytokines were detectable in saliva from 71 PMW and 67 RMPW. In the initial unadjusted model, IL-7, IL-10, and TNF-alpha exibited significant differences between RMPW and PMW. However, these differences became non-significant (p > 0.05) in the final model after adjusting for age, which implies a negligible effect of the investigated covariates on salivary cytokine levels when age was considered. Lower levels of IL-6 in PMW, which initially showed no significant difference, became borderline (p = 0.054) in the final model after adjusting for age.Conclusions: After adjusting for multiple factors, no significant difference was found in the salivary levels of the investigated cytokines between RMPW and PMW. Factors such as BMI, perceived health, serum cytokine levels, and periodontal parameters seem to minimally influence these levels in PMW. However, age may be a stronger confounding factor.