Browsing by Author "Sahin C."

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A comparative analysis of the effects of rotor molding clinches on torque ripple of mutually coupled SRMS
(2011-01-01) Sahin C.; Amac A.E.; Karacor M.; Emadi A.
In this study, the mitigation of torque ripples at mutually coupled switched reluctance motor (MCSRM) is investigated experimentally. Although, MCSRMs have higher performance than classical switched reluctance machines (SRMs), they are not attractive enough due to their high torque ripples. There are many different methods to solve this problem. One of the methods is to change the geometric structure of the machine. The analyses of previous studies show that despite there being favorable results in applications, the molding pins of the machines are neglected in those works. A motor that gives positive results may get affected negatively by its random molding during generation. In this research, a 3-phase average 100 watt MCSRM is chosen for analysis and effects on torque of the geometric point of molding pins in the machine are studied comparatively. Maxwell 2D program is used for analyses and two different models are compared with each other. The obtained results show that torque ripple of the machine is lower when molding pins are closer to the rotor post, and it is reduced by 12% at 6 Amps in the proposed MCSRM. © 2011 Praise Worthy Prize S.r.l. - All righs reserved.
New amide based iridium(III) complexes: Synthesis, characterization, photoluminescence and DFT/TD-DFT studies
(2018-01-01) Sahin C.; Goren A.; Demir S.; Cavus M.S.
New iridium(iii) complexes with 2-(3-fluorophenyl)-4-methylpyridine as cyclometalated ligands and 2,2′-bipyridine-4,4′-dicarboxamide derivatives as ancillary ligands were synthesized and characterized by FTIR, NMR, MS, UV/Visible, and fluorescence spectroscopies and cyclic voltammetry. The effects of different solvents and substituents on the photophysical properties of the complexes have been investigated. The complexes show tunable photoluminescence wavelengths depending on solvent polarity in the 548 nm to 610 nm range where the emission colour can change from green to orange-red. The complexes exhibit high photoluminescence quantum yields between 0.41 and 0.75, which may be attributed to the change in the transition dipole moment originating from the amide group upon electronic excitation. The calculated HOMO and LUMO energy levels of complexes 1-7 are in the -5.51 to -5.60 eV and -3.37 to -3.40 eV ranges, respectively. The ground and excited state properties of 1 have been fully investigated by means DFT and TD-DFT methods respectively. The general trends of observed data have been successfully represented and quantified by computational data.
Reducing torque ripple of switched reluctance machines by relocation of rotor moulding clinches
(2012-11-01) Sahin C.; Amac A.; Karacor M.; Emadi A.
Switched reluctance machines (SRMs) are of great interest because of their simplicity, low-cost, reliability, robustness, fault-tolerance and extended-speed constant-power operation. However, conventional SRMs suffer from high torque ripples. There exist several methods, which have been proposed to reduce torque ripples. One of the proposed methods is to change the geometric structure of the machine. However, analysis of the state-of-the-art designs show that, despite achieving favourable results in applications, the moulding pins of the machines are normally neglected. A motor that gives positive results may get affected negatively by its random moulding during its manufacturing. In this paper, mitigation of torque ripples in short-pitched SRMs (SPSRMs) and fully-pitched SRMs (FPSRMs) are investigated. Three-phase SPSRM and FPSRM are chosen for this study and the effects of the geometric points of moulding pins in the machines are studied comparatively. Maxwell 2D program is used for the analysis and two different models are compared for both SPSRM and FPSRM. The obtained results show that the torque ripples of the two machines are lower when moulding pins are closer to the rotor position. It is reduced by 2.56% at 10 Amps in the proposed SPSRM and 12% at 6 Amps in the proposed FPSRM. It is also observed that the applied method is more effective in reducing torque ripples of FPSRMs than SPSRMs. © 2012 The Institution of Engineering and Technology.