Alternately zero voltage switched forward, flyback multi resonant converter topology

The high efficiency multi-resonant converter is capable of operating at a high frequency with high power density [W/inch³]. However, the resonant voltage stress of 4∼5 times the input voltage increases the conduction losses because of on-resistance of a MOSFET. In this paper, the alternatively zero voltage switched forward multi resonant converter topologies are suggested to solve these problems. Comparing to the input voltage, it is about 2∼3 times the input voltage. Two multi resonant switches are turned on at the zero voltage and can be controlled more easily. Especially, the operational characteristics and the transient response are considered for alternated forward ZVS MRC. 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%. The stabilization is achieved from the experimentally measured results of phase margin and gain margin of loop gain.