An application of full bridge switched mode power supply with high power and soft switching

Full bridge phase shifted PWM DC-DC converter is a very suitable topology for the highpower, soft switched, switched-mode power supplies. This circuit, its power switches operateunder zero voltage transition (ZVT) without being used any snubbers, enables high switchingfrequency for improved power density. Having merits of soft switching, this circuit, has beenhaving more attraction due to the optimized circuit models eliminating its disadvantages.In this study, firstly, a basic information about switched-mode power supplies, phase shiftedPWM control and soft switching tecniques is given. Then full bridge phase shifted PWM DC-DC converter is examined in detail including some important design criteria. Finally aswitched-mode power supply prototype is fabricated with 220 V AC input voltage, 220 kHzswitching frequency at 1400 W (20V / 70A) output power. Judging the results of thelaboratory experiments, it is verified that this topology is a good choice for high frequency,high power applications having less switching losses owing to ZVT. In addition to this, it isseen that conventional system has to be optimized because of drawbacks like narrow ZVTrange, loss of duty cycle and very severe parasitic oscillations across rectifier diodes.Keywords : High power DC-DC converter, full bridge, soft switching, zero voltage transition,zero voltage switching, phase shifted PWM.JURY:1. Y. Doç. Dr. A. Faruk BAKAN (Supervisor) Date : 20.09.20052. Prof. Dr. Hacı BODUR Page: 743. Y. Doç. Dr. Tuncay UZUN