Papers by Erdal Bekiroğlu
Electric Power Components and Systems
In this study, the speed control of the vector controlled induction motor was implemented by usin... more In this study, the speed control of the vector controlled induction motor was implemented by using hard switching and soft switching inverters. A TMS320F243 digital signal processor was used to implement control algorithm during practical implementation. With the use of the vector control, complex structure of the controller is simplified, and dependence to variations of the motor parameters is reduced.
Electric Power Components and Systems
Electric Power Components and Systems
Journal of Bionic Memory, 2022
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Journal of Alloys and Compounds, 2016
This comprehensive study declares experimentally the effect of diffusion annealing temperature in... more This comprehensive study declares experimentally the effect of diffusion annealing temperature in a range of 600 Ce850 C on the electrical, superconducting and microstructural properties of the Audiffusion-doped Bi-2212 polycrystalline compounds with the aid of the available experimental methods such as bulk density, dc resistivity (r-T), transport critical current density (J c), X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and electron dispersive X-ray (EDX) measurements. The experimental findings of the dc electrical resistivity and XRD investigations present that the Au impurities are effectively entered into the crystalline structure of the Bi-2212 system. In fact, the EDX examinations confirm that the Au impurities may mostly be substituted for the Sr-sites in the Bi-2212 crystal matrix due to the increase of electronegativity. Besides, the J c measurements present that highly dispersed Au impurities with higher electronegativity bind tightly to form the effective nucleation centers through the intra-grain and inter-grain boundaries for the flux pinning of the vortices in the Bi-2212 crystal structure. Furthermore, it is observed that the vital characteristics, being responsible for newly/novel and feasible market areas for the universe economy, improve significantly with the increment in the diffusion annealing temperature up to the value of 800 C as a consequence of the retrogression in the disorders, dislocations, defects, lattice strains, misorientations and local structural distortions in the Cu-O 2 consecutively stacked layers, leading to the development of the metastability (enhancement of the hole trap energy) belonging to the superconducting materials studied. However, after the critical temperature point, the properties recrudesce dramatically due to the penetration of excess Au foreign impurities in the Bi-2212 crystal structure. In more details, the XRD measurement findings display that the diffusion annealing temperature promotes significantly the high phase as a consequence of the increment in both the average crystallite size and c-axis length or decrement in the constant parameter a. In this respect, the solid compound produced at the annealing temperature of 800 C obtains the maximum (minimum) c-axis length of 35.43 Å (5.32 Å) and average grain size of 68.7 nm. Similarly, the same sample exhibits the smoothest and densest surface morphology with the best interaction between the superconducting grains and largest crystalline distribution. Finally, the highest T onset c and T offset c values are noted to be about 89.78 K and 89.01 K, respectively. This is attributed to the fact that the Au nanoparticles penetrated transit from inherently overdoped nature of the Bi-2212 compound to optimally doped state. To sum up, the annealing temperature of 800 C favors the Bi-2212 superconducting ceramics for usage in the large scale applications.
Journal of Alloys and Compounds, 2016
This study deals with the determination of optimum preparation conditions (press load, annealing ... more This study deals with the determination of optimum preparation conditions (press load, annealing temperature and time) for the Bi-2223 superconducting compound with the aid of both the experimental methods regarding dc resistivity, transport critical current density and powder X-ray diffraction measurements and statistical approaches including response surface explorer based on BoxeBehnken designs for the first time. It is found that the Bi-2223 polycrystalline compound prepared under 300 MPa pressure load at 840 C for 48 h presents the highest formation of Bi-2223 phase due to the considerable elimination of the impurity scattering and lattice strain in the crystal structure. On the other hand, the sample prepared at 860 C under 350 MPa for 48 h exhibits the worst characteristic features of high T cphase as a consequence of the enhancement in local structural distortions, dislocations, defects and disorders in the CueO 2 consecutively stacked layers. Thus, the latter condition causes to both the degradation in amplitude of pair wave function (decrease in the overlapping of Cu 3d and O 2p functions) and metastability due to the reduction of hole trap energy. In this respect, the best material displays the largest T onset c of 110.63 K and T offset c of 108.46 K values while the worst material obtains the smallest values (T onset c of 95.45 K and T offset c of 45.32 K). Similarly, the maximum J c value of 818 A/cm 2 is experimentally observed for the best compound whereas the worst sample obtains the smallest value of 112 A/ cm 2. The decrement in the J c parameter is attributed to the regression of intergrain coupling and flux pinning vortices in the Bi-2223 crystal structure due to the increment of misorientations and especially grain boundary weak-interactions in the crystal system. The XRD results also reveal that the combination of 300 MPa press load, 840 C annealing temperature and 48 h annealing time for the preparation condition promotes seriously the high T c-phase as a consequence of the enhancement in the average crystallite size and lattice parameter c or decrement in the a-axis length. Accordingly, the best material obtains the largest c-axis length of about 37.22 Å and average grain size of 71.4 nm but the smallest lattice parameter a of about 5.29 Å. At the same time, the surface response designs of statistical analyses show that the optimum preparation conditions are defined to be 306.5657 MPa press load, 840 C annealing temperature and 48 h annealing time to maximize the high T c-phase (with the maximum T onset c
Journal of Medical Systems
A toothbrush/dentifrice abrasion machine was developed to use in dental research laboratory. The ... more A toothbrush/dentifrice abrasion machine was developed to use in dental research laboratory. The mechanism was designed as a hexagonal block driven by two stepping motors which move the mechanism in four directions. In order to control the stepping motors speed, position and direction commands or signals were generated by a software written in C Programming Language and then these commands were applied the stepping motor drives through parallel port of a personal computer. The toothbrush/dentifrice abrasion machine was finally used to measure different longevity of tooth brush. It was experimentally shown that the mechanism can be used for highly accurate position and speed applications.
superconductors were prepared by standard solid-state reaction methods. Doping of Bi-2223 was car... more superconductors were prepared by standard solid-state reaction methods. Doping of Bi-2223 was carried out by means of iron diffusion during sintering from an evaporated iron film on pellets. The investigations consist of SEM, dc resistivity and hardness measurements. These measurements indicated that the Fe doping and diffusion-annealing time increased the T c , J c , Vickers hardness (H 0), Young's modulus(E), yield strength(Y), fracture toughness(K IC) values and improved the grain connectivity. The mechanical properties of the samples were found to be load dependent and on the diffusion-annealing time. In addition, we calculated the load independent H 0 , E, Y, and K IC of the samples. Possible reasons for the observed improvements in the superconducting and mechanical properties due to Fe diffusion are discussed.
2009 XXII International Symposium on Information, Communication and Automation Technologies, 2009
In this study, the speed control of the vector controlled induction motor was implemented by usin... more In this study, the speed control of the vector controlled induction motor was implemented by using hard switching and soft switching inverters. A TMS320F243 digital signal processor was used to implement control algorithm during practical implementation. With the use of the vector control, complex structure of the controller is simplified, and dependence to variations of the motor parameters is reduced.
2009 35th Annual Conference of IEEE Industrial Electronics, 2009
In this study, simulations of two methods used for minimizing the switching losses occur in DC/AC... more In this study, simulations of two methods used for minimizing the switching losses occur in DC/AC inverters with PWM that is used extensively because of its high power density, fast response and control facility were carried out. First method which can be applied easily is the resonant link inverter. The other one is the resonant transition zero current switching inverter,
2014 International Conference on Renewable Energy Research and Application (ICRERA), 2014
The global microgrid market is promptly flourishing as government and private sector willingly to... more The global microgrid market is promptly flourishing as government and private sector willingly to support actively. Todays, many countries and government have encouraged installing renewable energy farms for example wind farms and solar farms etc., and huge research has started in various aspect of it at the university level. The energy market in the United States is the largest market which has already taken a clear lead and they have mainly focused on remote microgrid and military microgrid. In European Union region, microgrids have reached in mature technology to participate in utility grid. However, in Asia-Pacific and Far East region has huge potential to grow up renewable energy market in future due to emerging economies to overcome power shortages/power outages and low grid connectivity. This paper presents several distributed generation around the European Union region and we have tabled testbeds information together. It helps the researcher to visualize today's microgrid and insight perceiving the possible evolvement of future grid. The study has concluded emphasizing the remarkable findings and potential research areas that would enhance for microgrid facilities.
IEEE EUROCON 2009, 2009
In this study, an automatic synchronization unit has been developed for the parallel connection o... more In this study, an automatic synchronization unit has been developed for the parallel connection of synchronous generators. Two synchronous generators are connected in parallel automatically with the developed control unit. Synchronous generators are also connected in parallel with the line. The voltages, frequencies, phase sequences and synchronism time data have been transferred to the microcontroller. These data are monitored and evaluated by the control algorithm coded into the microcontroller. Parallel operation of generators are realized automatically when all parallel connection conditions are occur. The system doesn't require additional measuring tools for monitoring and control processes. The developed automatic synchronization unit is fast, cost effective, reliable and precise to be used for monitoring, measurement and parallel operation of the synchronous generators.
Sensors and Actuators A: Physical, 2005
In this study, remote control of an ultrasonic motor has been implemented by using a standard GSM... more In this study, remote control of an ultrasonic motor has been implemented by using a standard GSM mobile phone. To drive the ultrasonic motor a digitally controlled drive system has been designed. Then a tone decoder circuit and microcontroller have been added between output of a mobile phone and the drive system of the motor. This system is flexible to be controlled with both GSM and DTMF based phones. With the developed drive and control system the overall control of the ultrasonic motor has been achieved. The system has been tested for different speed, position and direction conditions successfully. The experimental results verify that the GSM controlled drive system is highly effective, reliable, proper and applicable to achieve remote control of the ultrasonic motor. This study gets novel and important point of view for GSM based remote control applications addition to the control of ultrasonic motors.
Physica B: Condensed Matter, 2008
We have investigated the effect of addition of Gd in Bi 1.8 Pb 0.35 Sr 1.9 Ca 2.1 Cu 3 Gd x O y s... more We have investigated the effect of addition of Gd in Bi 1.8 Pb 0.35 Sr 1.9 Ca 2.1 Cu 3 Gd x O y superconductor with x ¼ 0, 0.1, 0.2, 0.3, 0.4 and 0.5. The samples were prepared by standard solid-state reaction methods. The investigation consisted of X-ray diffraction (XRD), scanning electron microscopy (SEM), dc electrical resistivity, hole concentration and transport critical current density measurements. Transport measurements indicated that the superconducting transition temperature, transport critical current density and hole concentration values of the samples strongly depend on the Gd addition. The values of T c , and J c of the samples decreased with the increase in Gd addition. When Gd addition ratio was increased, surface morphology and grain connectivity of the samples were observed to degrade from SEM investigations and phase ratio of the high-T c (Bi-2223) phase to the low-T c (Bi-2212) phase decreased (XRD measurements). The possible reasons for the observed degradation in superconducting and microstructure properties of Bi-2223 due to Gd addition were discussed.
Journal of Electroceramics, 2007
Piezoelectric driven ultrasonic motors have been attracted as considerable actuators for the serv... more Piezoelectric driven ultrasonic motors have been attracted as considerable actuators for the servo speed and position applications in recent years. These motors have important features and advantages to be preferred in the special movement applications. Ultrasonic motors have different operating principles and different drive and control systems than the electromagnetic motors. In this study, microcontroller based digitally controlled drive system has been proposed for a travelling-wave ultrasonic motor. Drive system includes power circuit, interface electronics circuits and microcontroller parts. Power circuit is combined from half-bridge serial-resonance inverter to provide highfrequency two-phase voltages. Interface circuits include gate drive, direction control, opto-coupler and filter circuits. Microcontroller is programmed to generate required digital control signals for overall control of the motor. Related to the reference speed, the microcontroller generates control signal resulting proper driving frequency. Consequently, the actual motor speed tracks the reference speed precisely. The speed feedback is taken from optical encoder and transmitted to the controller as digital speed and position signals. The developed drive system has been tested experimentally. The obtained results show the effectiveness and reliability of the proposed system. The microcontroller based drive system can be applied easily and successfully to the ultrasonic motor.
Journal of Electroceramics, 2007
Speed, position and load characteristics of the ultrasonic motor is considerably influenced from ... more Speed, position and load characteristics of the ultrasonic motor is considerably influenced from the input characteristics such as driving frequency, magnitude and phase difference of phase voltages. Input and output characteristics of a traveling-wave ultrasonic motor have been investigated from the experimental point of view in the present study. For this aim, a half-bridge serialresonance inverter based drive system has been designed and then implemented. The inverter is featured with pulse width modulation and pulse frequency modulation techniques. The frequency, amplitude and phase angle of twophase sinusoidal output of the driver has been designed to be changed for the control purpose. Then the measuring circuits and tools have been set up to obtain required measurements. Input characteristics such as duty ratio of control signal-dc reference voltage, dc reference voltagedriving frequency and output characteristics such as driving frequency-rotor speed, driving frequency-feedback voltage, phase voltage-rotor speed are obtained from the experiments. Also load characteristics are studied with experiments. Afterwards these characteristics are discussed in details. This study gives a systematical experimental approach in order to demonstrate operating and control principles and characteristics of the travelling-wave ultrasonic motor.
IEEE Transactions on Power Electronics, 2005
This paper presents a highly effective load adaptive drive system to control the speed of a trave... more This paper presents a highly effective load adaptive drive system to control the speed of a travelling-wave ultrasonic motor. The motor driver was built based on the two-phase high-frequency inverter using the mechanical resonant frequency of the ultrasonic motor. To digitally control the drive system, a TMS320F243 digital signal processor was adapted to the driver. The developed system includes two feedback loops; speed control loop and feedback voltage-resonant frequency tracking loop. The driving frequency was used as a control input to control the motor. Direct pulse-width modulation (PWM) control was used to obtain the required driving frequency. The developed drive system was experimentally tested under several operating conditions. The obtained results demonstrated the effectiveness of the drive system for high performance drive applications.
Energy Conversion and Management, 2004
In this paper, position control of an ultrasonic motor was implemented on the basis of fuzzy reas... more In this paper, position control of an ultrasonic motor was implemented on the basis of fuzzy reasoning. A digitally controllable two phase serial resonant inverter was developed to drive the ultrasonic motor by using a TMS320F243 digital signal processor. The driving frequency was used as a control input in the position control loop. The position characteristics obtained from the proposed drive and control system were demonstrated and evaluated by experiments. The experimental results verify that the developed position control scheme is highly effective, reliable and applicable for the ultrasonic motor.
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Papers by Erdal Bekiroğlu