Resonant operated buck converter with reduced device switching stress with power factor improvement

This paper presents a new resonant operated method for an ac to dc converter having reduced device stress. The converter is operated in buck converter mode. An additional switch is used to operate the devices in such a manner, that the charging and discharging take place in a resonant fashion. A higher efficiency can be achieved by turning off the switch under zero current switching (ZCS). The converter is further modified to operate with two switches in a diode bridge converter instead of three switches. Complete theoretical analysis, simulation results and experimental data on a 500W converter are presented to demonstrate the superiority of the new control strategy with reduced device stress. The input power factor is found to be over 0.996.