Alternated forward multi resonant converter

The high efficiency multi-resonant converter (MRC) is capable of operating at a high frequency because the losses are decreased due to the resonant tank circuit. Such a few MHz high frequency applications provide high power density (W/inch³) for the converters. However, the resonant voltage stress across the switch of the resonant tank circuit is 4~5 times the input voltage. This high voltage stress increases the conduction losses because of on-resistance of a MOSFET with higher rating. In this paper, the AT forward MRC is suggested to solve these problems. It´s circuit construction and operation differ from the CM forward MRC. The operational modes of the AT forward MRC are divided to 8 equivalent modes according to the two switching sequences. Mode analysis and experimental results are covered using the equivalent circuits modeled over all of the paper. The operational principle of the resonant converter was verified through the experimental converter with 48 V input voltage, 5 V/50 W output voltage/power and PSpice simulation. The measured maximum voltage stress is 170 V of 2.9 times the input voltage and the maximum efficiency is measured up to 81.66%