Yazar "Ghaderi, Davood" seçeneğine göre listele

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    Öğe
    Efficiency Improvement for a DC-DC Quadratic Power Boost Converter by Applying a Switch Turn-off Lossless Snubber Structure Based on Zero Voltage Switching
    (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.
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    Öğe
    Influence of a Proposed Switching Method on Reliability and Total Harmonic Distortion of the Quasi Z-Source Inverters
    (IEEE-Inst Electrical Electronics Engineers Inc, 2020) Hang, Liu; Subramaniam, Umashankar; Bayrak, Gokay; Moayedi, Hossein; Ghaderi, Davood; Minaz, Mehmet Recep
    An Improved Sinusoidal Pulse Width Modulation (ISPWM) technique carried out to obtain pure sine waves for voltage and current signals in Quasi Z-Sourc Inverters (QZSIs) in the load side is given in this study. This switching method can be examined to two and multi-phase approaches simply through the addition of the same controller structure to per phase. This is the main advantage of the proposed converter to obtain higher voltage gains at the output ends of this inverter. The idea is to generate a positive rectified voltage at the output point of the QZSI and positive and negative rectified voltages at the output terminals of the QZSI in two-phase approaches to improve the quality of the output voltage of the F-Bridge Inverter (FBI). These rectified voltages are applied to the Full-Bridge Inverter (FBI) block and pure sine waves to obtain the load current and voltages. 1.34% of the Total Harmonic Distortion (THD) for the output voltage has been reported in the one-phase system while 0.88% of THD has been obtained in the two-phase approach. Besides, the reliability of the QZSI was tested through the Mean Time to Failure (MTTF) analysis with the values of the proposed components. The calculations show a very good result for the long-life of the converter. All experimental and simulations steps have been obtained for the same values of the components to support and confirm the accuracy and correctness of the proposed IMSPW. For the states of single-phase and two-phase converters, a 50 Hz sine-wave with 220 V and 440 V peak to peak amplitude has been acquired. Evaluations of the quality of the voltage and current waveforms related to different active (Resistive, P) and reactive (combination of Resistance and Inductance, QL) loads have been carried out. Experimental results show confirmation for all simulation and mathematical results.