Design Consideration of MHz Active Clamp Flyback Converter with GaN Devices for Low Power Adapter Application

摘要

With ever increasing demands of smaller size, lighter weight for all forms of consumer electronics, efficient power conversion with higher operating frequency has always be-ing pursued rigorously. This paper demonstrates high frequency, high efficiency and high power density design of active clamp fly-back converter for adapter application. Both the primary and sec-ondary switches are gallium nitride (GaN) devices which can sig-nificantly reduce the device related conduction and switching loss. The design procedures, including the selection of active clamping capacitor, optimization of flyback transformer, and EMI filter de-sign, are presented in detail. A 65W (19.5V/3.3A) prototype of ac-tive clamp flyback front end converter is developed to verify the feasibility of the system design. The prototype efficiency is 1~2% higher than the state of art product and the power density (exclude case) is more than 40W/in~3.