Yazar "Celebi, Mehmet" seçeneğine göre listele

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    Novel Control Scheme to Reduce THD in Bidirectional Three-Phase Inverter Using a Three-Phase Unfolder for the Grid Forming Operation
    (Wiley, 2025) Celebi, Mehmet; Ertekin, Davut
    Recent trends emphasise the significance of bidirectional power conversion systems in grid-forming operations. Minimising total harmonic distortion (THD) in these systems is crucial for enhancing power quality, efficiency and equipment lifespan. This study proposes a novel reference signal modification control scheme to reduce THD in a bidirectional inverter by adjusting the DC-Link Voltage reference based on AC load feedback. Comparative analysis with conventional systems across various load types demonstrates superior performance, particularly with induction machine loads. The proposed control model involves multiple stages, including error computation, averaging, dynamic error handling, reference modification and regulation using a PI control block. This approach effectively manages error dynamics in the inverter topology and eliminates electromagnetic interference in the PCB without determining any additional theoretical approach. Both simulated and experimental results validate the theoretical analyses, showcasing the efficacy of the proposed method. Its simplicity in modifying the reference voltage makes it suitable for situations where controllers lack the capability to effectively manage desired outputs.
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    The Design and Practical Realization of an Adaptable Grid Integrating Hydrogen Fuel Cell Setup With a Fuzzy-Logical Controller-Based SVPWM Boosted Inverter
    (Ieee-Inst Electrical Electronics Engineers Inc, 2024) Ertekin, Davut; Baltaci, Kubra; Toprak, Muhammed Zeyd; Celebi, Mehmet; Ozden, Mustafa; Siano, Pierluigi
    The primary and fundamental requirement for a fuel cell (FC) stack is its reliable operation under various operating conditions. When FC stacks are used as the input voltage source with high ripple currents, the overall lifespan of the FC system decreases. Hence, power converter configurations need to minimize the current ripples originating from these sources. Additionally, the generated voltage from the FC stack is often lower than the required voltage level for grid connection. This paper presents a fuzzy logic controller (FLC)-equipped high-gain single-switched DC-DC boost converter. The proposed power converter topology utilizes an improved switched inductor and switched capacitor configuration to minimize input current ripples and enhance the voltage gain. The switched inductor cell is designed in such a way that its inductors charge and discharge simultaneously, effectively minimizing the input current ripple. Additionally, the proposed DC-DC boost converter utilizes a switched capacitor cell to double the generated voltage. The FLC offers real-time visualization and digital signal processing capabilities, and it is compatible with MATLAB software. For grid connection purposes, a space vector pulse width modulation (SVPWM)-based switching system is recommended, utilizing a full bridge inverter. The SVPWM technique is implemented by representing the desired output voltage with an equivalent vector VREF rotating counterclockwise, integrated with a digital signal processing (DSP)-based controller. The DSP microcontroller employed in this study operates at an 80 Mb/sec sampling speed and offers several advantages, including the ability to perform complex calculations, implement advanced control algorithms, and process signals in real-time. These capabilities contribute to enhanced performance, efficiency, and accuracy. Laboratory studies have been conducted to validate the accuracy and effectiveness of the theoretical investigations.
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    (Kaunas Univ Technology, 2018) Ghaderi, Davood; Celebi, Mehmet; Minaz, Mehmet Recep; Toren, Murat
    So as to keep the converter in small size, high switching frequencies are normally used. As a result, in higher frequencies, switching losses seriously affect the efficiency. Current and voltage stresses on power switch can be serious problems particularly in high amount of powers where MOSFET switches are generally applied. A snubber circuit can reduce or eliminate spike voltage and currents, decrease the di/dt or dv/dt values on power switch and transfer the power losses on switch to load and increases the lifelong of the switch. This study presents a method for improving the power transmission efficiency for DC-DC Cascaded Boost Converter and uses a passive snubber sub-circuit, which consists of an inductor, a capacitor, and two diodes for reducing the switching loss. The role of resonant capacitor of this structure is discharging directly through the load and is parallel with the power switch. Thus, it is effective in lossless switching and increasing the DC voltage gain of the boost converter. Soft switching is achieved through the use of a LC resonant tank circuit. The tank circuit is responsible for zero voltage switching (ZVS) and zero current switching (ZCS), eliminating the power loss in the switches appreciably. The proposed structure, done by MATLAB SIMULINK based on simulations, has shown more efficiency toward the same structure without snubber circuit. Besides, an application has been conducted in laboratory scales, and results confirm theoretical findings.