The Dual Forward Converter Based On Single-Stage APFC Soft-Switch

The double forward converter based on the soft-switch activepower factor correction（APFC）has many advantages compared withthe traditional single-stage forward converter. First, it has high powerfactor and low harmonic content; second, the soft-open andsoft-shutdown of the power switches can be realized, so the efficiency ofthe converter is greatly improved; then, the high output power and highreliability of the converter meet the growing needs of complexapplications.In this paper, the double forward converter based on thesingle-stage soft-switch APFC with165-265V input and48V/2A outputis the main research object. First, the double forward converter based onthe single-stage soft-switch APFC consists of two basic units. The firstunit is boost-type single-stage APFC converter, the second unit is activeclamp converter. The operation processes of various operating modes ofthe converteris are analyzed in detail; second, the main circuit of thesystem is simulated by use of simulation software Saber. The converter’ssmall-signal model is established, stability of the system is simulated byuse of simulation software Matlab, and the correctness of the theoreticalanalysis is verified; then, a double forward converter prototype based onthe single-stage soft-switch APFC is designed, the detailed schematic ofprototype circuit, the design methods of the parameters of majorcompents and the model selection of major compents are provided inthis parper; finally, the test results of four PWM drive waveform, thefour waveform of DS and GS in MOSEFT, the primary side waveformof transformer，the input voltage, input current waveform and the outputvoltage waveform, experimental waveforms are roughly consistent withthe simulation waveforms, so the correctness of the theoretical analysisand simulation analysis are verified. The power factor, efficiency, inputvoltage regulation ratio and load regulation ratio are respectively testedin detail, and their harmonics are analyzed. It is proved that theperformance indexes of the prototype meet the design requirements. At the last of the paper, a summary for the paper is completed.Some suggestions are proposed for next work.