Analysis And Research Of Winding Loss Based On Flyback Circuit

As a common converter of switching power supply,flyback converter has been widely used in low power applications.With the development of soft switching technology,the winding loss of magnetic components has become the most important part of the overall machine loss.At present,the theoretical research on the winding losses of magnetic components is limited to simple winding arrangements and air-gap-free core structures.Therefore,this paper focuses on the in-depth analysis and research of high-frequency magnetic element winding losses with air-gap core structures.The winding loss of magnetic components includes three analysis methods: theoretical,measured and simulated.Theoretical analysis is the basis of the research.The current Dowell model and its corresponding improvement schemes have certain limitations due to the analysis based on the air gap-free core structure.Aiming at the theoretical analysis of magnetic elements with air gaps,from the perspective of the influence of air gaps in the magnetic field,this paper proposes a method of equivalently replacing the air gap with surface current and equivalently replacing the core boundary with mirror current.Based on Biot-Savart's law,the winding loss on a single two-dimensional surface is calculated.Finally,the entire winding loss of the magnetic element is theoretically calculated.Experimental testing of magnetic element winding losses is a necessary means to verify the correctness of the theoretical analysis method.The traditional magnetic element loss measurement method is difficult to directly obtain the winding loss data because the measured data includes both core loss and winding loss.Although the windingshort-circuit method is an effective experimental test method,it is limited to being applied to magnetic elements without air gaps.Aiming at air gap magnetic components,this paper proposes a scheme to replace the air gap with a winding.The feasibility of the scheme is demonstrated theoretically.Based on the winding short-circuit method,an experimental test is performed to replace the air gap with the winding.accuracy.Simulation analysis of winding losses of magnetic components is also an effective way to obtain winding losses.Although the current 3D simulation scheme is structurally closest to the actual model and the simulation results have high accuracy,it requires a lot of computer resources and simulation time.Aiming at the traditional complex three-dimensional model simulation analysis,this paper proposes a simplified two-dimensional simulation scheme in the RZ coordinate system.It is theoretically analyzed that the two-dimensional simulation analysis method can meet the simulation accuracy requirements.A two-dimensional simulation analysis was performed,and the simulation results of its winding loss were finally obtained.Finally,the experimental test of the winding loss of the actual prototype magnetic component is carried out,and the experimental test results are compared with the simulation analysis results,and the error causes are analyzed in depth.