Research On Magnetic Integration Theory And Method Of Two-phase Interleaved Parallel LLC Resonant Converter

With the continuous development of switching power supply industry,the resonant converters using interleaved parallel technology and magnetic integration technology have been widely used.Therefore,this paper mainly studies the integrated magnetic components in the interleaved parallel LLC resonant converters.Firstly,the working principle of the full-bridge LLC resonant converter and the working process of the two-phase interleaved parallel LLC converter are analyzed,the fundamental equivalent model is deduced,the characteristics of the converter is analyzed.And the optimal resonant parameters are found to meet the soft switching characteristics of the resonant converter,and the parameter design is completed.Secondly,the paper analyzes and designs the magnetic integrated transformer in resonant converter,analyzes the problems existing in the traditional "EE" type of integrated transformer,and proposes a new type of "E+E" type magnetic integration transformer structure,establishes the circuit and magnetic circuit model,analyzes the core loss and winding loss,and completes the design and verification of transformer parameters.The simulation and comparison of traditional transformer and new transformer are carried out by ANSYS software,and the transformer experimental prototypes are made.Then,the coupling inductor in resonant converter is analyzed and designed,the effect of air gap of magnetic core on the performance of coupling inductor is analyzed.A new coupling inductor structure is proposed.The circuit model and magnetic circuit model are established,the principle of current sharing is analyzed,and the influence of resonance parameter deviation on the current sharing characteristics of coupling inductor under different coupling coefficients is analyzed,and the optimal coupling coefficient is determined.The parameters of coupling inductor are designed.The coupling inductor is modeled and simulated by ANSYS software.The resonance inductance value is determined by air gap adjustment,and the prototype is completed.Finally,the simulation analysis of the interleaved parallel LLC resonant converter is carried out by using PSIM simulation software,the soft switch characteristics is verified.According to the parameters of resonant converter,the main circuit components selection and control circuit design are designed,the experimental platform is built,and the experimental waveforms of the resonant converter based on traditional magnetic elements and new magnetic elements are given respectively.The results show that compared with the traditional magnetic integration structure,the efficiency of the converter based on the new type of magnetic integration structure is generally improved in the whole load range,the peak efficiency is improved by 1.71% and the full load efficiency is improved by 1.47%.It is proved that the new magnetic integrated structure is beneficial to reduce the loss of the converter and the advantages of the structure are verified.There are 63 figures,6 tables and 55 references in this paper.