Analysis and Optimal Design of High Frequency and High Efficiency Asymmetrical Half-Bridge Flyback Converters

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The asymmetrical half-bridge (AHB) flyback converter is capable to achieve zero voltage switching (ZVS) and has lower voltage stress compared to the active clamp flyback converter (ACF). This topology gives much margin for components selection and transformer turns ratio design. It is well adapted to voltage step-down applications. However, the optimal design for AHB flyback converter taking current dip effect causing by components parasitic capacitances, and each component effect to power loss into consideration has never been explored. This paper gives detailed operation and mathematical analyses of this effect. The optimal design procedure with the consideration of each circuit parameter is presented in this paper. The transformer benefits low power loss from interleaving winding layout. A 56W/inch3 1MHz 65W prototype with 100V-250V input is built to verify the feasibility of the converter. Experimental results show the peak efficiency 96.5% is achieved with 127V input and the whole system efficiency under the entire input voltage range is above 93%.
Original languageEnglish
JournalIEEE Transactions on Industrial Electronics
Issue number99
Number of pages9
Publication statusAccepted/In press - 2020


  • AHB flyback converter
  • High efficiency
  • Voltage step down applications

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