Optimization Design Of Magnetic Components Of High Frequency DC-DC Converter Based On Planar Magnetic Technology

When the planar transformer is applied in high-frequency scenarios,problems such as serious parasitic effects,sharp increase in winding losses,and far exceeding core losses are exposed.It is of great significance to optimize the parasitic parameters and loss of planar transformer at high frequency and optimize its structure.In addition,the inter-group parasitic capacitance generated by the primary and secondary windings of the planar transformer provides a flow path for the common-mode current in the converter,resulting in large electromagnetic interference.The traditional discrete electromagnetic interference(EMI)filter is not easy to achieve high power density.If the EMI filter and the output filter are integrated by planar magnetic integration,it will have great advantages in reducing cost,volume and weight.Therefore,this paper will optimize the design of magnetic components in half-bridge LLC resonant converter based on planar magnetic technology.Firstly,the high-frequency planar transformer is designed and optimized based on the half-bridge LLC resonant converter.The preliminary design of the planar transformer is completed.According to the different interleaving degrees of the primary and secondary windings of the transformer,four transformer schemes are proposed to optimize the optimal structure.In order to optimize the parasitic capacitance,the optimization is completed by referring to the low common mode current design scheme.By means of magnetic simulation and thermal simulation of finite element simulation software,the key characteristics of planar transformer are finally verified by comparing the loss,distributed capacitance and other parameters of the above design scheme.Then,the magnetic integrated filter is designed and simulated.The main work includes : Discuss the structure of LCL filter and EMI filter after symmetrical splitting,and propose a reasonable winding structure of magnetic integrated filter from the performance point of view;the power loss of the magnetic integrated filter is analyzed,and the core loss,winding loss and air gap loss are analyzed according to the working conditions.Through the joint simulation of Maxwell and Simplorar,the magnetic integrated structure of half-bridge LLC circuit and integrated filter is built.Based on this,the designed filter circuit is analyzed to view the magnetic circuit and magnetic flux distribution under excitation.By comparing the EMI noise amplitude and total harmonic distortion(THD)before and after the access filter,the correctness of the design is verified.Finally,a 300 W half-bridge LLC resonant converter experimental prototype is built.The performance of the planar transformer designed in this paper is tested under different loads,and its efficiency curve and temperature rise under full load are tested,which proves that the design meets the design requirements.