Browsing by Author "Ozel, Erdogan"

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Analysis and Design of Stacked Coupled Inductor Quadratic Boost Converter With a Lossless Snubber Cell
(Wiley, 2024) Koc, Yavuz; Birbir, Yasar; Ozel, Erdogan
This paper introduces the stacked coupled inductor quadratic boost converter with an inductorless, passive lossless snubber cell suited for high step-up applications with various microgrids. Some design constraints can be selected from the voltage gain techniques of the high step-up converters to obtain the solution of improvement performance of converter. The proposed converter utilizes quadratic boost converter and coupled inductor to attain high voltage gain beyond the voltage multiplier/lift cells. In this proposed converter, the use of a stacked coupled inductor type introduces the leakage inductor to snubber cell as an inductor without using an extra inductor in proposed snubber cell. Thus, a regenerative snubber cell is used to achieve a high system efficiency. Compared with earlier counterparts, the solution of attaining a high voltage gain in the proposed converter and passive lossless snubber cell leads to an increase in the converter's performance, reliability, and robustness. The theoretical expectations are supported by simulations and verified by experimental results obtained by implementing a 300-V, 120-W prototype.
Comprehensive Dielectric Analysis of Schottky Devices with Cu-Doped DLC Interlayer: Temperature Effects and Polarization Mechanisms
(Elsevier, 2026) Baran, Ahmet; Ozel, Erdogan; Evcin-Baydilli, Esra; Kaymaz, Ahmet; Altindal, Semsettin
In this study, the temperature-dependent dielectric properties of a Cu-doped diamond-like carbon (DLC) interfacial-layered Schottky device (SD), fabricated by the electrochemical deposition method, were systematically investigated in terms of the dominant polarization mechanisms. Impedance measurements, performed over the temperature range of 80-410 K, were used to calculate the dielectric constant (e'), dielectric loss (e ''), loss tangent (tan(S)), ac conductivity (cac), and complex electric modulus (M*), including its real (M ') and imaginary (M '') components. The results reveal that all dielectric parameters exhibit three distinct behaviours within three temperature regions, namely low-temperature (LTs: 80-170 K), moderate-temperature (MTs: 200-290 K), and high-temperature (HTs: 300-410 K) regimes. This behavior indicates a pronounced sensitivity of the DLC interfacial layer to temperature. It was also observed that different polarization mechanisms, including dipolar, trapping-related, electronic, and space-charge polarizations, become dominant depending on the temperature and applied voltage range. Owing to the heterogeneous structure of the SD, the contribution of Maxwell-Wagner polarization, as a specific form of space-charge polarization, becomes particularly significant in the HTs region. Moreover, Cu doping leads to an increase in carrier density within the DLC layer, enhancing the tunneling probability and strengthening space-charge polarization through the increased availability of free carriers.