Quasi-Resonant Parameter Design and Optimization of Single-Switch Flyback Converter

This paper mainly solves the problem that MOS’s valley switching value of drain-source voltage (V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS(on)</inf>) in the Quasi-Resonant (QR) flyback converter cannot be precisely controlled during the resonance time. Traditional flyback converters operating in hard-switching mode suffer from significant switching losses, which adversely affect overall circuit efficiency. To mitigate this issue, a parameter design and optimization method is proposed to achieve precise control of V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS(on)</inf> during the resonance time, thereby reducing switching losses and enhancing system efficiency and reliability. First, the causes of switching losses are theoretical analyzed, and methods for reducing these losses are presented. Second, the operational mode of the QR flyback converter is analyzed, and formulas for QR parameter optimization are derived through model analysis. Subsequently, a systematic parameter design and optimization method is established based on the derived formulas, and prototype design specifications are provided. Finally, experimental results validate the feasibility and correctness and of the proposed method for precise control of V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS(on)</inf> during the QR interval.