Yazar "Akkaya, Ramazan" seçeneğine göre listele
Listeleniyor 1 - 15 / 15
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Control of Venturini Method Based Matrix Converter in Input Voltage Variations(INT ASSOC ENGINEERS-IAENG, 2009) Karaca, Hulusi; Akkaya, RamazanMatrix converter is a single-stage converter which directly connects a three-phase voltage source to a three-phase load without dc-link components. Therefore, any harmonic distortion and imbalance in input voltage directly reflect to the output of the converter. Recently, many researchers have made an effort to cope with this problem. In this paper, under distorted input voltage conditions, behaviors of the MC controlled with Venturini method are analyzed and a PI controller based compensation method to prevent negative effects of input voltage is proposed. Since the proposed method is based on closed loop control of the output currents, it not only reduces the output harmonic contents but also ensures a stable control of the load currents. Some results are presented to prove the effectiveness of the proposed compensation technique.Öğe A control scheme employing an adaptive hysteresis current controller and an uncomplicated reference current generator for a single-phase shunt active power filter(TUBITAK SCIENTIFIC & TECHNICAL RESEARCH COUNCIL TURKEY, 2014) Dogan, Huseyin; Akkaya, RamazanIn recent years, active power filters (APFs) have become popular because of their excellent current harmonics and reactive power mitigation ability. The performance of the APF is directly related to the selected control strategy, which is mainly divided into 2, the reference current generation and current control. Most of the reference current generation methods are very complicated and require precise mathematical expressions. Moreover, being the most preferred current control method, conventional hysteresis controllers have a fixed bandwidth, which causes different total demand distortion values under different load conditions. In this study, a novel control scheme for a single-phase shunt APF is proposed. The proposed scheme uses an uncomplicated modification of the sine multiplication method for extraction of the reference filter current. Moreover, it employs an adaptive hysteresis current controller that changes its bandwidth according to the active power demand of the load. Thus, the requirements of the current harmonics limits specified in IEEE Std. 519-1992 are always fulfilled under different load conditions. A single-phase shunt APF controlled by the proposed scheme is modeled and simulated under nonlinear load conditions using MATLAB/Simulink. The simulation results indicate that the APF effectively compensate the current harmonics and reactive power at the point of common coupling of the AC mains.Öğe Cost optimization of submersible motors using a genetic algorithm and a finite element method(SPRINGER LONDON LTD, 2007) Cunkas, Mehmet; Akkaya, Ramazan; Bilgin, OsmanThis paper presents an optimal design method to optimize cost of three-phase submersible motors. The optimally designed motor is compared with an industrial motor having the same ratings. The motor design procedure consists of a system of non-linear equations, which imposes induction motor characteristics, motor performance, magnetic stresses, and thermal limits. The genetic algorithm (GA) is used for cost optimization, and a software algorithm has been developed. As a result of the realized optimization, besides the improvements on the motor cost, motor torque improvements have also been acquired. The 2-D finite element method (FEM) is then used to confirm the validity of the optimal design. Computer simulation results are given to show the effectiveness of the proposed design process that can achieve a good prediction of the motor performance. Through the studies accomplished, it has been observed that submersible induction motors' torques and efficiencies improve, their length reduces, and hence some materialÖğe The Design and Implementation of a Microcontroller-Based Single Phase Online Uninterrupted Power Supply With Power Factor Correction(2009) Kayabaşı, Ahmet; Akkaya, RamazanIn this study, the design and implementation of a microcontroller-based single phase on-line UPS (Uninterrupted Power Supply) with PFC (Power Factor Correction) were made practically. SP-320-24 SMPS (Switch Mode Power Supply) module was used to correct the input power factor. Input power factor value was held at the desired value in uninterrupted power supply topologies. In the realized system, two PIC16F876 were used as microcontroller. One of them was used to generate sinusoidal PWM (Pulse Width Modulation) signals that are used to drive n-channel MOSFETs in push pull inverter and to assure feedback control. Other one was used to control and display units. Harmonics were eliminated and output filter was simplified by using sinusoidal PWM technology.Öğe Design optimization of induction motor by genetic algorithm and comparison with existing motor(2006) Çunkaş, Mehmet; Akkaya, RamazanThis paper presents an optimal design method to optimize three-phase induction motor in manufacturing process. The optimally designed motor is compared with an existing motor having the same ratings. The Genetic Algorithm is used for optimization and three objective functions namely torque, efficiency, and cost are considered. The motor design procedure consists of a system of non-linear equations, which imposes induction motor characteristics, motor performance, magnetic stresses and thermal limits. Computer simulation results are given to show the effectiveness of the proposed design process. © Association for Scientific Research.Öğe Dynamic Simulation of SVM Based Direct AC/AC Converter(IEEE, 2014) Karaca, Hulusi; Akkaya, RamazanIn this study, direct AC/AC converters controlled with space vector modulation (SVM) method are modelled in Matlab&Simulink. Direct AC/AC converters produce directly the three-phase load voltages which have variable frequency and variable amplitude, without rectifying the fixed three-phase input voltages. Simulation results are analyzed for output voltages with various frequency and amplitude.Öğe An effective real coded GA based fuzzy controller for speed control of a BLDC motor without speed sensor(TUBITAK SCIENTIFIC & TECHNICAL RESEARCH COUNCIL TURKEY, 2011) Aydogdu, Omer; Akkaya, RamazanIn. this study, an effective Real Coded Genetic Algorithm (GA) based optimal fuzzy controller is proposed. The fuzzy controller is used for sensorless speed control of a Brushless DC (BLDC) motor in DSP based application system. The advantages of adopting a real coded GA for the design and optimization of fuzzy controllers, which have a great deal of design and optimization parameters, are analyzed. Having accomplished optimization of developed fuzzy control system, a multi-objective performance index has been defined and it has been used as an objective function to be minimized in the real coded GA. Thus, the system can obtain optimal design parameters in a short time without the need of an expert assistance. Convergence of the control system performance index and speed responses of the BLDC motor have been provided as a result of study. The obtained results indicate that there is close agreement between simulation and experimental results.Öğe Extended kalman filter sensor fusion and application to mobile robot [Genişletilmiş Kalman Filtresi İle Algilayici Tümleştirilmesi Ve Gezer Robotlara Uygulamasi](2004) Canan, Süleyman; Akkaya, Ramazan; Ergintav, SemihThe main problem in mobile robot is the error accumulation in its position in continuous navigation. In this study the localization of the mobile robot is done with gyroscope and odometric sensors by using the dead-reckoning method. To estimate precise and correct position the dead-reckoning system should be aided by an external absolute positioning sensor. The continuous error accumulation in dead reckoning should be reseted, the position and direction state variables must be updated with an absolute sensor positioning data. The GPS (Global Positioning System) system, which is an absolute positioning system, is used in complement with the dead reckoning system to estimate precise and correct positioning data. The extended Kalman Filter is used for sensor fusion purposes. The Kalman Filter has the ability to make an optimal estimate of the state variable when the data is immerged in white noise. To implement the algorithm, the mobile robot kinematic model was obtained. The kinematic model of the robot is in non-linear nature. Thus the model is linearized in order to use with the Kalman Filter algorithm. Finally the data obtain from the two different navigation system is perfectly fused and showed with computer simulations. © 2004 IEEE.Öğe A genetic algorithm optimized ANN-based MPPT algorithm for a stand-alone PV system with induction motor drive(PERGAMON-ELSEVIER SCIENCE LTD, 2012) Kulaksiz, Ahmet Afsin; Akkaya, RamazanArtificial neural network (ANN) based maximum power point tracking (MPPT) algorithm makes use of the advantages of ANNs such as noise rejection capability and not requiring any prior knowledge of the physical parameters relating to PV system. This paper proposes a genetic algorithm (GA) optimized ANN-based MPPT algorithm implemented in a stand-alone PV system with direct-coupled induction motor drive. The major objective of this design is to eliminate dc-dc, converter and its accompanying losses. Implementing offline ANN in DSP needs optimization of ANN structure to obtain an ideal size. GA optimization was used in this study to determine neuron numbers in multi-layer perceptron neural network. Another objective of this work is to prevent the necessity of the trade-off between the tracking speed and the oscillations around the maximum power point. Hence, varying step size is used in MPPT algorithm and PI-controller is adopted for simple implementation. Simulation and experimental results have been used to demonstrate effectiveness of the proposed method. (C) 2012 Elsevier Ltd. All rights reserved.Öğe İndüksiyonlu ısıtma uygulaması için akım beslemeli paralel rezonans devreli bir inverterin simülasyonu ve gerçekleştirilmesi(Selçuk Üniversitesi Teknik Bilimler Meslek Yüksekokulu, 2012) Anadol, Mehmet Ali; Akkaya, RamazanBu çalışmada, indüksiyonlu ısıtma uygulamaları için tek fazlı, köprü tipi, akım beslemeli paralel rezonans devreli bir inverterin Pspice programı kullanılarak simülasyonu ve prototip tasarımı pratik olarak gerçekleştirilmiştir. İnverter devresinde iki yönlü gerilim anahtarı olarak MOSFET kullanılmıştır. İndüksiyonlu ısıtma sistemi, ısıtma işlemi boyunca açık çevrim modunda çalıştırılmıştır. Deneysel sonuçlar, Pspice simülasyon programından elde edilen sonuçlarla karşılaştırılmış ve sonuçların birbiriyle uyum içinde olduğu görülmüştür.Öğe Modelling and simulation of matrix converter under distorted input voltage conditions(ELSEVIER SCIENCE BV, 2011) Karaca, Hulusi; Akkaya, RamazanMatrix converter is an energy conversion device which directly connects a three-phase voltage source to a three-phase load without dc-link components. Therefore, the output of the matrix converter is directly affected by the disturbance or imbalance in the input voltages. Many researchers have made an effort to overcome this problem in recent years. In this paper, the behaviors of the matrix converter controlled with the optimum-amplitude Venturini method are investigated and a novel compensation technique based on fuzzy logic controller is proposed to eliminate the undesirable influences of the input voltage under the distorted input voltage conditions. The proposed technique is based on closed loop control of the three-phase output current to enhance the output performance of the matrix converter. The mathematical model of the proposed system is developed. The simulation of the development model is performed in Matlab&Simulink. Some results demonstrating validity of the proposed compensation technique are presented. (C) 2010 Elsevier B.V. All rights reserved.Öğe A Novel Compensation Method Based on Fuzzy Logic Control for Matrix Converter under Distorted Input Voltage Conditions(IEEE, 2009) Karaca, Hulusi; Akkaya, Ramazan; Dogan, HueseyinMatrix converter (MC) is a direct energy conversation device without de-link components. Therefore, the output of the converter is directly affected by the disturbances in the input voltages. Many researchers have made an effort to overcome this problem. In this paper, the behaviors of the MC have been investigated under the distorted input voltage conditions. A fuzzy logic control (FLC) based novel compensation method is proposed, which performs close loop control of the output current to improve the output performance of the MC. Some results are presented to prove the effectiveness of the proposed compensation technique.Öğe A Novel Hybrid Compensation Method Reducing the Effects of Distorted Input Voltages in Matrix Converters(KAUNAS UNIV TECHNOLOGY, 2019) Karaca, Hulusi; Akkaya, RamazanMatrix converters have the most compact and efficient AC-AC converter structure due to the lack of the DC intermediate components. The matrix converter makes a single-stage conversion directly connecting any terminal of voltage source to any terminal of load. This outstanding feature leads to some problems that must be overcome under the distorted input voltage conditions. A matrix converter has low immunity to power source disturbances, because it has no DC intermediate circuit. Any disturbance in the power source creates a negative effect on the load of the matrix converter and on the current drawn from the source. In this study, a novel compensation method, which provides immunity against input voltage disturbances, is suggested for the matrix converter. The suggested method has a hybrid structure, which includes both feedforward and fuzzy logic controller based feedback methods. The effectiveness and accuracy of the suggested new hybrid compensation approach are proved by the various results obtained.Öğe Torque optimization of submersible motors using evolutionary algorithms(2011) Çunkaş, Mehmet; Akkaya, Ramazan; Bilgin, OsmanThis paper presents the design optimization method to maximize the torque of submersible motors. In optimization, genetic algorithms have been used because of its superior features over some other evolutionary algorithms. The magnetic analysis of motor has been implemented with two-dimensional finite elements method. The optimization results obtained from genetic algorithms have been verified by finite elements method. It is seen that the results are in compliance with Finite Element results. Besides, Genetic algorithms have been tested by using different number of populations; crossover and mutation rates. The results have shown that submersible induction motors' torques and efficiencies are improved and material savings are obtained. © 2011 IEEE.Öğe Training Data Optimization for ANNs Using Genetic Algorithms to Enhance MPPT Efficiency of a Stand-Alone PV System(TUBITAK SCIENTIFIC & TECHNICAL RESEARCH COUNCIL TURKEY, 2012) Kulaksız, Ahmet Afşin; Akkaya, RamazanMaximum power point tracking (MPPT) algorithms are used to force photovoltaic (PV) modules to operate at their maximum , power points for all environmental conditions. In artificial neural network (ANN)-based algorithms, the maximum power points are acquired by designing ANN models for PV modules. However, the parameters of PV modules are not always provided by the manufacturer and cannot be obtained readily by the user. Experimental measurements implemented in the overall PV system may be used to obtain the ANN dataset. One drawback of this method is that the generalization ability of the neural network usually degrades and some data reducing the effectiveness of the network may exist. A genetic algorithm can be used to automatically select the important data among all the inputs, resulting in a smaller and more effective dataset. In our study, a genetic algorithm is used to improve the MPPT efficiency of a PV system with induction motor drive by optimizing the input dataset for an ANN model of PV modules. A variable frequency volts-per-Hertz (V/f) control method is applied for speed control of the induction motor, and a space-vector pulse-width modulation (SV-PWM) method is used to operate a 3-phase inverter. Both simulation and experimental results are presented to demonstrate the validation of the method.
