Research On Optimization Design And Application Of Flyback High Frequency Transformer

Flyback switching power supply has the advantages of energy saving,high efficiency,stability and reliability,and has become the mainstream power supply products.As the core component of flyback switching power supply,high frequency transformer plays a decisive role in the performance of power supply.This paper mainly focuses on the design,optimization and application of high-frequency transformer,including the design method of high-frequency transformer,winding structure optimization,parasitic parameters on the impact of switching power supply,as well as the evaluation of switching power supply carrying capacity and core selection.In order to improve the design efficiency and accuracy of high frequency transformer,a design method based on finite element method is proposed.The design steps and flow chart are given.A high frequency transformer is designed by using this method.The design results are in good agreement with the test results of the prototype.This method overcomes the traditional design method.Errors caused by empirical formulas.For the purpose of reducing winding loss of the designed high frequency transformer,the effects of air gap edge field effect,skin effect and proximity effect on winding loss are analyzed,and the structural optimization measures of air gap avoidance and cross-position of windings are proposed.The simulation results of field-circuit coupling verify the correctness of the optimization effect of winding structure.Based on the two optimized winding structures,the influence mechanism of leakage inductance and distributed capacitance of high frequency transformer on flyback switching power supply is analyzed.The field-circuit coupling simulation method is used to compare the voltage and current stresses of two cross-transposition structures in reducing parasitic parameters.The results show that the cross-transposition structure I is more suitable for situations with high EMCrequirements.In order to further improve the reliability of flyback switching power supply,on the premise that high frequency transformer does not appear core saturation in the full range of operating temperature,a method for evaluating the on-load capacity of flyback switching power supply is proposed.The detailed evaluation process and evaluation criteria are given,and the accurate evaluation of flyback switching power supply under actual on-load conditions is realized.Based on the magnetic saturation characteristics of high frequency transformer,a method of selecting magnetic cores based on I-P characteristics of power supply is proposed.Fitting formulas of I-P characteristics corresponding to different magnetic cores are obtained,and reasonable selection of magnetic cores for switching power supply in different power application areas is realized.The simulation results of field-circuit coupling agree well with the experimental results,which verifies the correctness of the evaluation method and the core selection method.