Browsing by Author "Tarhan, C."

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    A robust voltage control method for universal EV battery charger LLC resonant converters
    (IEEE, 2019) Daş, Y.; Tekin, Ahmet; Boztepe, M.; Tarhan, C.; Electrical & Electronics Engineering; TEKİN, Ahmet
    In this study, a novel control method for LLC resonant converter with wide output voltage range and constant switching frequency is proposed targeting wide range of Electric Vehicle (EV) battery charger standards. In conventional LLC converter control topologies, in order to reach lower output voltage levels, switching frequency happens to move away from the resonance frequency, increasing in most of the cases. However, the switching losses due to switching devices start to become the main bottleneck at high switching frequency operation. Furthermore, high switching frequency operation may cause irreversible inrush current damage at the input terminals during the start-up with corresponding overshoot at the output voltage as well, risking the clients on this particular supply. The work presented in this paper proposes a robust and reliable control solution for these particular resonant converter drawbacks. Theoretical analysis for both conventional and proposed control methods are presented in detail. In order to show the effectiveness of the proposed technique, performance metrics of the both are compared experimentally on an LLC resonant converter specification having an output voltage range of 150-500 V with a maximum output power of 7.5 kW.
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    Total harmonic distortion and power factor improvement technique for CRM flyback PFC converters
    (IEEE, 2019) Kavcı, Mustafa; Tekin, Ahmet; Tarhan, C.; Electrical & Electronics Engineering; TEKİN, Ahmet; Kavcı, Mustafa
    In many of today's solid-state lighting applications, Critical Conduction Mode (CCM) Flyback PFC converter is a popular solution due to its limited component count and simple structure with respect to other SMPS topologies. As described in international standards documents (IEC/EN 61000-3-2), drivers are required to demonstrate a power factor results greater than 0.9 and lower THD for power levels above 25W. Due to non-sinusoidal input current waveform of the traditional constant-on-time control method, achieving improved PF and THD is quite difficult. In this paper, a new control method is introduced in an effort to improve power factor and total harmonic distortion of Voltage Mode CRM Flyback PFC Converter. The work proposes injection of a compensating sin(ωt) signal component in the feedback path utilizing an additional primary transformer winding to linearize the current from the source. The detailed theoretical analysis is presented along with measurement results of a 30W high-power system prototype.