Browsing by Author "Karafil, Akif"
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Item Change Effect of LCL Filter Parameter Values and Series Damping Resistor Value in Single Phase Grid Connected Inverter(EMO Bilimsel Dergi, 2020) Karafil, AkifIn this study, LCL filter parameters of a single phase grid connected inverter were calculated. The change of total harmonic distortion (THD) of the grid current and power loss values when the calculated LCL filter parameters and series damping resistor were increased and decreased by 50% was analyzed and the most appropriate values were determined. Analysis studies were carried out using the PSIM simulation program. The study had a power of 1 kW and proportional resonant (PR) control was used in current control and T/4 delay PLL structure was used in PLL algorithm. According to the results of the analysis, it was determined that increasing the inductor values decreased the THD value of the current and the amount of power loss. In addition, decreasing the damping resistor value also decreased THD and power loss values. In LCL filter design, it was seen that it would be appropriate to increase the inductor values and to decrease the series damping resistor value.Item Comparison of the various irregular pulse density modulation (PDM) control pattern lengths for resonant converter with photovoltaic (PV) integration(Journal of the Faculty of Engineering and Architecture of Gazi University, 2021) Karafil, AkifIn this study, the maximum power obtained from photovoltaic (PV) panels was transferred the load using the proposed 8, 16 and 32 irregular pulse density modulation (PDM) pattern controlled series resonant converter. In the study, changes in the system occurred due the variations in PDM pattern lengths were analyzed. The output power was controlled by providing maximum power point tracker (MPPT) at different solar irradiation values with varying PDM pattern lengths. Zero current switching (ZCS) conditions were achieved by using phase locked loop (PLL) technique at each power point of the PV system. Therefore, soft switching was realized by continuously tracking the appropriate switching conditions at the resonant frequency. Incremental conductance (IC) algorithm was used to track the maximum power in PV panels and tracking efficiency of a novel PDM controlled IC MPPT algorithm was obtained above 99%.Item Direct Active-Reactive Power Control of Three Phase PWM Rectifier(Gazi University Journal of Science Part C: Design and Technology, 2020) Özbay, Harun; Karafil, AkifIn this study, simulation and experimental studies of direct power control for three phase pulse width modulation (PWM) rectifier circuit application are presented. The main advantage of PWM rectifier circuits over diode rectifier circuits is that the DC voltage and power factor are adjustable. Thus, the harmonic level of currents drawn from the grid can be kept within international standards. In this study, an algorithm was developed for direct power control of PWM rectifier using PI controller. In this way, the active power quality transferred to the load was increased by precisely adjusting the DC voltage on the load. In addition, reactive power support was provided according to the requirement of the grid. Thus, the performance of simulation and experimental studies conducted for the developed direct power transfer algorithm has been proved. Simulation studies were conducted using PSIM program, all control algorithms were written in block C and embedded code was produced by the program. A prototype was designed to transfer 1 kVA of power to verify the developed algorithms.Item Effect of passive series damping resistor on single phase grid connected inverter with LCL filter(Pamukkale University Journal of Engineering Sciences, 2020) Karafil, AkifIn this study, analysis, design, simulation and the application of a single phase grid connected inverter circuit with LCL filter were realized at 600 W power and the effect of passive series damping resistor on the circuit was examined. Proportional integral (PI) was used for the active power control, proportional resonant (PR) controller was used for the current control and T/4 delay phase locked loop (PLL) algorithm was used for frequency control of the grid. The analyses were conducted without series damping resistor and the simulation and the experimental results were obtained for different power values. Then, the series damping resistor was connected to the LCL filter in the inverter circuit and the results were obtained again. The obtained simulation and the experimental results showed that the oscillations in the grid current decreased and the power transitions became more uniform with the series damping resistor.Item LCL Filter Design and Active Power Control for Single Phase PWM Rectifier(Konya Journal of Engineering Sciences, 2020) Karafil, Akif; Özbay, HarunThe most important advantage of pulse width modulated (PWM) rectifier circuits over traditional diode rectifier circuits are the adjustable DC voltage and power factor. However, due to the hard switching condition in the PWM rectifier circuits, high order current harmonics occur in the grid. In order to reduce these high order harmonics, a filter must be used on the grid side. Although there are many filter types, the LCL type filter is the most commonly used filter type. In this study, simulation and experimental results of active power controlled single phase PWM rectifier circuit were presented by calculating LCL filter. The simulation of the study was conducted in the PSIM program. All control software of the system was achieved by writing codes to the C block in the program, and the embedded codes were produced by the program. The system was designed to transfer 400 W active power and PI was used for power control, PR controller for current control and T/4 delay phase locking loop (PLL) algorithm for grid frequency control.Item Sliding mode PLL-PDM controller for induction heating system(Turk J Elec Eng & Comp Sci, 2021) Özbay, Harun; Karafil, Akif; Öncü, SelimIn this study, a sliding mode controlled phase locked loop (SMC-PLL) was developed for induction heating (IH) applications with a resonant inverter. PLL applications are widely used in induction heating applications to achieve zero voltage switching and zero current switching. In many PLL applications, the frequency tracking is too slow and unreliable. Therefore, a sliding mode controller was developed to provide robust and fast PLL. Furthermore, a pulse density modulation (PDM) control strategy was developed to work at the resonant frequency for all power levels. The PDM power control is a good solution for the design of high-frequency inverters because of a great reduction of switching losses and electromagnetic noise. The PDM pattern for the desired output power is determined according to the set temperature value of the work piece. The proposed system was simulated in PSIM and a 250-W laboratory prototype was implemented with operating frequency of 35–42 kHz.Item The Effect of Using Bypass Diode in Series Connected Photovoltaic (PV) Panels on System Power in Partial Shading Condition(Dokuz Eylül Üniversitesi Mühendislik Fakültesi Fen ve Mühendislik Dergisi, 2021) Karafil, AkifGerilimin yüksek değerde olması istenilen fotovoltaik (FV) sistemlerde paneller seri olarak bağlanır. Seri bağlanan FV sistemlerde en önemli sorunlardan biri bina, ağaç, direk vb. nedenlerden dolayı panel üzerinde kısmi gölgenin oluşmasıdır. Kısmi gölgeleme, panel üzerinde sıcak noktaların oluşmasını neden olarak hem panele zarar verir hem de sistemin verimini düşürür. Bu olumsuz durumların engellenebilmesi için panellere paralel olarak bypass diyotları bağlanır. Bu çalışmada, kısmi gölgelenme durumundaki seri bağlı FV panel sayısının sırasıyla 2, 4 ve 6 olacak şekilde arttırılarak sistemde bypass diyotunun kullanılıp kullanılmamasına göre meydana gelen kayıp oranı incelenmiştir. Panel sayısı arttırılırken sistemin toplam gölgelenme oranı da azaltılmıştır. Çalışma, PSIM benzetim programı kullanılarak gerçekleştirilmiştir. Yapılan inceleme sonucunda kısmi gölgelenmeye maruz kalmış seri bağlı FV panellerde panel sayısı arttırılıp toplam gölgelenme oranı düştükçe bypass diyotunun kullanıldığı sistemlerde kayıp oranı azalmaktadır. Bypass diyotunun kullanılmadığı sistemlerde ise panel sayısı arttırılıp toplam gölgelenme oranının düşürülmesi kayıp oranını azaltmamakta aksine arttırmaktadır. Yani; bypass diyotsuz sistemlerde seri bağlı FV panel sayısı arttırıldığında düşük gölgelenme oranlarının bile verimliliği önemli ölçüde düşürdüğü görülmüştür.