Design Of A Dual-tube Forword Converter Based On APFC

In recent years,the world has begun to pay attention to the environment and nonrenewable resources,and the use of green energy has also attracted more and more attention.Since the rectified load connected to the power grid will cause distortion of the input current waveform,high-order harmonic currents will be injected into the power grid,which reduces the stability and reliability of the power grid;therefore,active power factor correction circuits are a necessary part of many electrical equipment.Also meets the core requirements of green energy.The design is aimed at the complicated categories of current APFC circuit topologies,and most of them are concentrated on the boost type and its improved APFC circuit.For the current situation where there is little research on the step-down APFC circuit,based on a large amount of literature,the article first introduces and summarizes a variety of step-down PFC circuit topologies at home and abroad,and illustrates the advantages and disadvantages of various circuit topologies.The development direction of APFC technology and the limitation of traditional boost BOOST power factor correction circuit are analyzed.The main purpose of this design is to make it meet the green energy standards proposed by the country on the basis of the research on the step-down APFC.This article discusses the step-down active power factor correction technology,and studies the main circuit structure of the step-down active power factor correction circuit—Sepic topology.In addition,the relationship between its input current and input voltage is analyzed.The step-down power factor correction circuit is verified by Matlab simulation.The step-down active power factor correction circuit reduces the output voltage.It greatly simplifies the design of the downstream converter,and is suitable for applications such as high power density power adapters and base station power supplies.This article compares the characteristics of various switching power supply converter topologies,analyzes the development background of switching power supply technology,and looks forward to the development prospects of switching power supply technology.In this paper,the principle analysis and design of the main double-tube forward circuit are carried out.Analyze the principle of the circuit topology and analyze the origin and operating characteristics of the dual-tube forward topology.The principle of the optocoupler isolation circuit is analyzed,and the principle of voltage regulation of the circuit output is analyzed and introduced,and the design of the control circuit and the calculation of the parameters are completed.The purpose of this design is to apply synchronous rectification technology to improve the circuit of low-voltage high-current switching power supplies and improve the efficiency of electric energy conversion.The main circuit adopts a dual-tube forward topology,which has a high magnetic core utilization rate and does not require a magnetic reset winding.The secondary side of the main circuit uses the current popular synchronous rectification technology to greatly improve the efficiency of power conversion;the control chip adopts Voltage control chip SG3525,the drive circuit uses a transformer to drive two MOS transistors in isolation.The over-current protection circuit uses a typical NE555 monostable circuit and has an over-current alarm function.