Research On High Power Density Resonant DC/DC Converter Based On Magnetic Integration Method

The concept of"Green Development" has been deeply rooted among the people,and the low-carbon development trend with the aim of "Carbon Neutral 2060" has brought great challenges to the economical and efficient operation of the power supply system.With the input and output of various forms of energy,there comes a large amount of power loss in the process of energy conversion.At present,the hot-button issues in power electronics field still is how to improve the power density of the converter.The plane transformer with magnetic integration technology has the advantages of small volume,good heat dissipation,Designable leakage inductance and excitation inductance,and small equivalent impedance,which provides a new idea for improving the power density of the converter.But there still lacks the theoretical guidance when it comes to how to effectively use magnetic integration to improve the power density of resonant DC/DC converter.Firstly,the model of bidirectional resonant DC/DC converter is presented to analyze the influence of electric circuit from the matching capacitance on the first and second sides of the transformer.Then we could get the impact on the voltage gain of converter from quality factor,the ratio of excitation inductance to leakage inductance and the distribution of resonant capacitance by analyzing the circuit characteristics.Secondly,analyzing the design methods of plane transformer.First,taking into account the influence of the converter’s the working frequency and rated power and other factors on the system,select the appropriate magnetic core.Second,by analyzing the influence of skin effect and proximity effect on the current density distribution of windings,the effect of spatial magnetomotive force distribution results on transformer leakage inductance and AC resistance under different winding arrangements is determined.Then combined with the transformer actual requirements of resonant DC/DC converters,choose the sandwich arrangement mode as the transformer connection mode in this paper.Third,aiming at the loss problem caused by uneven current distribution,a method to select the width of winding is proposed to obtain the distribution formula of current density in horizontal direction.In order to reduce AC resistance,designing criteria for plane transformer with variable winding width.Lastly,the comparison between modeling analysis and simulation results of ANSYS Maxwell 3D verifies that the winding variable width method under the sandwich arrangement effectively reduces the AC loss of the planar transformer compared to the winding equal width method.Finally,an isolated DC/DC converter is developed for 100kHz and 3kVA.The DC/DC system constructed by the planar converter designed in this article has a power density that is 12.39%higher than the DC/DC system constructed by the traditional toroidal winding high-frequency transformer.