Development of a High-Power-Density Quasi-Resonant Flyback Power Converter

The purpose of this paper is to develop a high-power-density flyback converter with quasi-resonant (QR) topology. QR topology has the valley-switching characteristics can improve the conversion efficiency with higher switching frequency. Therefore, the volume of magnetic components can be reduced. In this paper, a dynamic valley-switching control strategy is proposed to improve the switching loss for different load conditions. In addition, the synchronous rectification technology is used to reduce the secondary side conduction loss and switching loss. Finally, a 100-W QR flyback prototype is developed and built to verify the proposed control strategy and theoretical analysis. The specifications include input voltage range of 12 V to 36 V and output voltage of 24 V. As demonstrated in the prototype’s experimental results, the peak value of the conversion efficiency is 94.3%, and the power density is about 144 W/in3