Design and Implementation of Asymmetric Half-Bridge Flyback Converter for USB Power Delivery Applications

In this paper, a two-stage USB PD charger for wide output voltage range of various electronics products is implemented. The first stage is the boost power factor corrector (PFC) to achieve high power factor. The asymmetrical half-bridge (AHB) flyback is used as the second stage to provide electrical isolation. The energy is transferred to the load by the resonance between the leakage inductance and resonant capacitor with soft switching. A 140 W experimental prototype is implemented with input voltage of 90 V
ac
~ 264 V
ac
, rated output current of 5 A, and output voltage of 5/ 9/ 15/ 20/ 28 VDC. The experimental results reveal that the maximum efficiency and power factor of the boost PFC is 98.2% and 0.99, respectively. The maximum efficiency of the AHB flyback converter is 91.8%. The maximum efficiency of the overall system is 90.2%.