A Double ZVS-PWM Active-Clamping Forward Converter ... - Ivo Barbi

p 1.:a472a1.81.7401.6I .51.41.31.21.1I3624IZ 00 2’*I%] 95w857570e50955Fig. 10. Voltage and current in switch S4.(2Ndiv.; lOOV/div.; 2us/div.)I0 20 30 40 so10 [AIFig. 11. Output characteristic of the converter.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 IDFig. 12. Clamping characteristic of the converter.I I I I I0 12W 18MI 24au 3woPo WIFig. 13. Measured efficiency of the converter.VI. CONCLUSIONSAn new active-clamping ZVS-PWM dc-dc converterbased in two single forward-converters was proposed in thepaper. Analysis of the clamping characteristic, outputcharacteristic, commutation characteristic and designmethodology are presented.Experimental results show that the converter presents thefollowing features:0 Soft commutation of switches SI, S1, S3, S4 for any loadcurrent.The power flow from the input to the output iscontrolled with only two switches, SI and Sz. In this way,conduction losses of the converter are low. Besides, thecurrent flowing through the auxiliary switches SS and S4 isvery low.0 Overshoots voltages across the switches caused by thetransformer leakage inductance are reduced by the use ofactive clamping circuits.0 Good sharing of the voltage across the switches isobserved.REFERENCESJ. A. SabatB, V. Vlatkovic, R. B. Ridley, F. C. Lee, andB. H. Cho, “Design Considerations for High-VoltageHigh-Power Full-Bridge Zero-Voltage-SwitchingPWM Converter”, in IEEE Applied Power ElectronicsConference (APEC) Rec., 1990, pp. 275-284.E. Deschamps and I. Barbi, ”A New DC-to-DC ZVSPWM Converter for High Input Voltage Applications”,in IEEE Power Electronics Specialists’ Conference(PESC) Rec., 1998, pp. 967-972.M. Miller, A. Buffh and U. Carlsson, “High FrequencyZVS for High Power Rectifiers”, in InternationalTelecommunication Energy Conference (MTELEC)Proc., 1993, pp. 424-430.N. Kutkut, G. Luckjitt and D. Divan, “A Dual BridgeHigh Current DC-to-DC Converter with Soft SwitchingCapability”, in IEEE Industry Applications Society(IAS) Conf. Rec., 1997, pp. 1398-1405.[SI B. Carsten, “Design Techniques for Transformers ActiveReset Circuits at High Frequencies and Power Levels”,in High Frequency Power Conversion (HFPC) conf.proc., 1990, pp. 235-246.[6] C. M. C. Duarte, and I. Barbi, “A Family of ZVS-PWMActive-Clamping DC-to-DC Converters: Synthesis,Analysis, Design, and Experimentation”, in IEEETransactions on Circuits and Systems, august 1997,~01.44, NO. 8. pp. 698-704.(71 R. Torrico Bascope, “Isolated ZVS-PWM dc-dcConverters with Two Input, Single Transformer andSymmetrical Rectifier”, Doctoral Thesis in Preparation,Power Electronic Institute-Federal University of SantaCatarina, Brazil, 1998.60 1