Research On Soft-switched Flyback Converter With Low Power

Nowadays,switching power supply,for its small volume,light weight and high efficiency,have been used in computer,communication,electric power,traffic,aeronautics and astronautics as well as medical area.With the increasing using of the portable devices in our society,in order to meet the higher market requirement,the switching power supply should improve their performance,like smaller volume and better transferring efficiency.The traditional rectifier filter circuit have low power factor,which can generate big harmonic wave current,and pollute the electric power grid grievously.Adding a PFC before the convertor can increase the power factor and then satisfy the standard of the harmonic wave.Besides,the higher frequency convertor is working,the more switching loss it has.To keep the convertor's high frequency and high power factor,we should rely on switching technology and synchronous rectification technology.Because of this,PFC,synchronous rectification technology and soft-switching power supply technology become hot spots.This paper researched on low power consumption soft-switching flyback convertor,the pre-stage of input is Boost PFC circuit,the mid-stage is soft-switching flyback circuit and the back-stage is synchronous rectification output circuit.First,this paper has compared the PFC technology and the APFC technology,and choosing the APFC plan.Second,this paper introduced the history along with the development of soft-switching technology and synchronous rectification technology.This paper introduced the principle of Boost APFC circuit in detail,and research on soft-switching flyback convertor in phases,giving the derivation process and working wave picture.Then the paper designed a soft-switching flyback circuit sample and gave the design method of it.Finally,system simulation and prototype test were carried out,giving the test waveforms of circuit key point.And the power factor value,harmonic current data,input voltage regulation rate,output load regulation rate and machine efficiency werealso tested.By analyzing those simulation waveforms and test data,proving that the prototype's testing metrics meet the expected design requirements,the correctness of this plan has been verified.In the end,this paper summarized the work of this topic,and put forward the direction of future research.