Analysis and design of Boost-LLC converter for high power density AC-DC adapter

This paper proposes the size reduction methods for two-stage Boost-LLC converter to achieve high power density in 60W AC-DC adapter. The two-stage converter has high component count, and the passive components such as inductor, transformer, and capacitor occupy the most of the area. In order to make the converter have small size, this paper proposes the size reduction methods of passive components: the design of low link voltage, the design of the resonant tank without additional inductor and with high resonant frequency, and the design of C-L-C filter replacing output capacitor. A 60W (16.8V/3.65A) prototype adapter is designed and implemented to verify the feasibility of the proposed methods. The converter achieves 14.5W/in3 power density with the methods.