Research On The Flyback Switching Power Supply Based On Dual Single-stage APFC

At present，with the rapid development of economy and the powerelectronics technology，the switching power supply is applied morewidely，its requirement for power factor and efficiency of the wholemachine is also increasing followed by its wide application. Usually，compared with two-stage PFC circuit, the single-stage PFC circuit has alot of advantages such as less components，lower cost，and higherefficiency. In order to improve the efficiency of switch power supply,the soft-switching technology is the most effective ways to reduce theswitch loss of the circuit. Therefore，it has great realistic significance toresearch the single-stage PFC and soft-switching technology.In this paper, in order to obtain the high efficiency, the authorabandoned the traditional PFC chip, and a single PWM control chip wasadopted to design a switching power supply with the power factorcorrection. Its structure is mainly divided into two parts：the single-stageBoost-PFC circuit and the flyback soft-switching circuit. The advantagesof the flyback converter and Boost converter are combined in the circuitstructure，so the new one possesses the advantages such as the powerfactor correction, simple structure, and low cost. At the same time，italso simplifies the control method, and reduces the difficulty of controlcircuit design.In the beginning of the article，the key technology of switch powersupply such as the power factor correction technology and soft switchtechnology is studied systematically. Then，it analyzes the operatingprinciple and process of the flyback soft-switching circuit based on dualsingle-stage APFC in the paper. Simultaneously, the working mode andcontrol mode of the Boost-APFC circuit are also introduced in detail.The detailed calculation and selection of main circuit components arealso discussed based on theoretical analysis that had been given outbefore; particularly, the detailed design of the isolation transformer withhigh frequency has been carried out. In addition, it has also carried onthe detailed explanation to each function module of output voltageduring the designed circuit. Finally，the circuits are simulated and analyzed in the open-loop and closed-loop conditions through using thesimulation software Saber. At the same time，some parameters’ tests ofthe experimental prototype are also carried on，which is mainly to verifysome performance indicators such as the efficiency of prototype，powerfactor，the regulation rate of input voltage，the adjustment rate ofoutput load and the harmonic analysis of input current. The results ofsimulation and test reflect that the theoretical analysis has its rationalityand feasibility，and also verify that the performance of experimentalprototype meets the design requirements very much.In the end of the thesis，the related work about this topic issummarized simply，and according to the design，the author put forwardown suggestions on areas that should be improved.