Hybrid-switching asymmetrical half-bridge flyback DC-DC converter
This paper proposes a hybrid-switching technique for asymmetrical half-bridge flyback converter. In this topology, the duty loss can be minimized because the active switches can achieve zero-voltage-switching (ZVS) and the output diode can be turned off at zero current, which result in higher efficiency, higher power density and universal input voltage range (90-264V). Moreover, this technique doesn't require any addition of components into the original topology and still employ the fixed frequency PWM, therefore the control method is simple and straightforward, while still being highly reliable.
Analysis and Optimal Design of High-Frequency and High-Efficiency Asymmetrical Half-Bridge Flyback Converters
The asymmetrical half-bridge (AHB) flyback converter is capable to achieve zero voltage switching and has lower voltage stress compared to the active clamp flyback converter. 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 article gives detailed operation and mathematical analyses of this effect. The optimal design procedure with the consideration of each circuit parameter is presented in this article. The transformer benefits low power loss from interleaving winding layout. A 56 W/inch3 1 MHz 65 W prototype with 100–250 V input is built to verify the feasibility of the converter. Experimental results show the peak efficiency 96.5% is achieved with 127 V input and the whole system efficiency under the entire input voltage range is above 93%.
AC/DC flyback converter with synchronous rectification
The design of a 70 W AC-DC converter is presented. The design is intended to achieve a good performance in terms of efficiency. This performance is reached using a quasi-resonant topology together with synchronous rectification on the secondary side. Comparisons between theoretical and experimental results are presented. The converter meets the no-load power consumption requirements indicated by the EU code of conduct.