Yazar "Borekci, Selim" seçeneğine göre listele

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    CURRENT FED SELF OSCILLATING ELECTRONIC BALLAST DESIGN WITH PUSH PULL INVERTER
    (Gazi Univ, Fac Engineering Architecture, 2009) Borekci, Selim; Oncu, Selim
    Electronic ballasts are commonly used due to several advantages; among electronic ballasts, self oscillating electronic ballasts are not only simple and cheap but also have high efficiency because of zero voltage switching technique. Current and voltage fed topologies are commonly used in electronic ballasts. When both topologies are compared, current fed has better start up transient response. In this study, current fed push pull inverter circuit is designed for three 36W T8 fluorescent lamps. In the design, push pull transformer is wounded on a partition bobbin. Although it has the advantages of easy and reliable production for industrial automation and lowering the cost of the circuit, the coupling between the coils is considerably weak. Because of this, the weak coupling is taken into account in the design. The design has agreement with experimental and simulation results.
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    DESIGN AND IMPLEMENTATION OF A SELF OSCILLATING INDUCTION HEATER
    (Gazi Univ, Fac Engineering Architecture, 2011) Bal, Gungor; Oncu, Selim; Borekci, Selim
    Self oscillating circuits do not require more complicated control circuit. So they can provide low cost power control with very simple control circuit. Because of these advantages the self oscillating circuit topology is widely used in some power electronics applications such as inverters and electronic ballasts. In this study, an application of self oscillating control technique was achieved on an induction heater driven by D-class inverter. Transistors used as power switches are triggered in order by the feedback signal which follows load current. For the developed self oscillating induction heating system, results obtained from simulations and experiments are compared and then presented.
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    ELECTRONIC BALLAST POWER CONTROL WITH MAGNETICALLY CONTROLLED COIL
    (Pamukkale Univ, 2008) Borekci, Selim; Oncu, Selim
    Electronic ballasts have several advantages over magnetic ballasts such as providing higher efficacy, better illumination quality, longer lamp life and smaller size. In this study, magnetically controlled inductor controls the florescent lamp power by changing the ballast impedance and resonant frequency and the proposed topology is implemented on self-oscillating push pull electronic ballast. In the proposed ballast power control technique, zero voltage switching (ZVS) is accomplished. The topology is also simulated in order to compare the results. Both simulation and experimental results have good agreement.
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    Switching-Mode BJT Driver for Self-Oscillated Push-Pull Inverters
    (Korean Inst Power Electronics, 2012) Borekci, Selim; Oncu, Selim
    Self oscillating current fed push pull resonant inverters can be controlled without using special drivers. Dc current flows through the choke coil and the power switches, although the driving signals of the power switches are sinusoidal. When the base current is near zero, the transistors cannot be operated in switching mode. Hence higher switching power losses and instantaneous peak power during off transitions are observed. In this study, an alternative design has been proposed to overcome this problem. A prototype circuit has been built which provides dc bias current to the base of the transistors. Experimental results are compared with theoretical calculations to demonstrate the validity of the design. The proposed design decreases the peak and average power losses by about 8 times, when compared to conventional designs.