A single-stage quasi-resonant flyback converter using a synchronous rectifier |
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Authors: | Kyu-Tae Kim Jung-Min Kwon |
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Affiliation: | 1. Department of Electronic and Electrical Engineering , Pohang University of Science and Technology (POSTECH) , Pohang, Kyungbuk, South Korea;2. Department of Electrical Engineering , Hanbat University , Daejeon, South Korea |
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Abstract: | A single-stage quasi-resonant flyback converter using the synchronous rectifier (SR) is proposed for improving power factor and system efficiency. This converter operates at the critical conduction mode with the variable frequency (VF) control to reduce the switching loss of the primary switch. The bulk capacitor voltage can be independent of the output load and kept within a practical range for the universal line input. Therefore, the problem of high-voltage stress across the bulk capacitor is reduced. The proposed converter features relatively low bulk capacitor voltage in the universal line voltage and also complies with the Standard IEC 61000-3-2 Class D limits. Moreover, since it uses the voltage-driven SR, it achieves a high efficiency. The operational principle and theoretical analysis are presented. Experimental results for a 100?W (19?V/5.3?A) adapter at the VF were obtained to show the performance of the proposed converter. |
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Keywords: | single stage power factor correction quasi-resonant converter synchronous rectifiers flyback converter |
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