Optimization of AHB Flyback Converter Based on Operation Mode Analysis

The asymmetrical half-bridge (AHB) flyback converter features zero-voltage switching (ZVS) for primary-side switches and zero-current switching (ZCS) for secondary-side rectifier under proper design. With its relatively wide dc gain range and high conversion efficiency, the AHB flyback converter shows good potential in high-power charger and adapter applications. However, due to its resonant operation, the accurate steady-state calculation and analysis become difficult, which leads to struggling of system design optimization. This paper presents a detailed study and analysis on the operation modes of AHB flyback converter to have a clear view of its steady-state characteristic. With that, system design optimization method is discussed. Finally, a 140W (28V/5A) prototype with CRM boost PFC in front is built in the lab based on the analysis.