High switching frequency, high efficiency CLL resonant converter with synchronous rectifier

In this paper, a CLL resonant tank (CLL) is presented as an attractive option in the front-end applications as DC/DC converter. This topology can achieve zero-voltage switching (ZVS) from zero load to full load, low turn off loss, ZCS for output rectifier, and easy to realize secondary rectification. A novel design methodology of CLL resonant converter is proposed based on the trade-off among efficiency, hold up time and ZVS requirement. A transformer structure for better performance in high frequency application is proposed. And current type synchronous rectifier (SR) drive scheme is used in this topology. An 800kHz, 300W CLL resonant converter prototype is made to verify the proposed design method.