Research And Realization Of Circulating Current Feedback Synchronous Rectifier Flyback Converter

Flyback converter has the advantages of simple circuit structure and low cost,which is widely used in small and medium power modules.However,when the flyback converter adopts diode rectifier mode,there will be serious rectifier loss when the output voltage is low,so synchronous rectifier technology is generally used.When flyback converter works under light load with synchronous rectification technology,it will generate reverse circulation,resulting in energy loss.So the energy loss of reverse circulation needs further study.The purpose of this thesis is to design a reverse circulation processing circuit to reduce the energy loss of the reverse circulation.Firstly,the thesis analyzes the causes of the reverse circulation problem of flyback converter with synchronous rectification,and makes a quantitative calculation of its energy loss,forming a mathematical model of the circulation energy loss.Secondly,three kinds of current conventional circulation suppression circuits are studied,their working principles are clarified,and their application shortcomings in engineering practice are demonstrated.In order to avoid these shortcomings,this thesis designs a loop energy feedback circuit,which can reduce the energy consumption by recycling the loop energy instead of restraining the reverse loop.The working principle and process of the circuit are calculated quantitatively,and its application advantages are also explained in detail.Finally,a prototype platform of the loop feedback flyback converter is built,on which the loop feedback circuit proposed in this thesis is tested to verify its energy recovery performance.The results show that the prototype has achieved the technical specifications of the design circuit,and achieved the expected effect of circulating energy recovery.On the whole,this thesis puts forward a new way to solve the problem of energy loss of reverse circulation: not restraining reverse circulation,allowing it to produce,and reducing energy loss by recycling its energy.The loop feedback circuit proposed in this thesis can reduce the energy loss,and the circuit structure is simple and easy to control,which can be used in engineering practice,and achieve the research goal of this thesis.