Research On A High Boost Ratio DC/DC Converter Based On GaN And LCLC Resonance

High boost ratio DC/DC converter based on LCLC resonance is a kind of significant special equipment widely used in the filed including military defense,industrial produc-tion and etc,but the size and weight of is strictly limited for the equipment applied in such as deep space exploration and space weapon.In order to further improve the operating frequency and performance of the converter,and further reduce the volume,the third-generation semiconductor power GaN device,planar transformer and high-order resonant converter were applied to the high-boost ratio DC/DC converter in this paper.This paper conducts research from four aspects: driving circuit for GaN device,planar transformer design,LCLC resonant converter,and DC/DC converter model,finally,a DC/DC con-verter prototype based on LCLC resonance was built.The main work is as follows:First,a comparative analysis of GaN devices and silicon(Si)MOSFET devices are carried out,and the reasons for the superior characteristics of GaN devices such as high electron mobility and low specific on-resistance are obtained from both the material and device structure aspects.On this basis,the problems and solutions when traditional drive design for Si MOSFET applied in GaN devices are analyzed.At the same time,the switch-ing process is analyzed,and the loss calculation method of GaN devices in unit switching cycle is obtained.Finally,the experimental results of switching devices performance tests were tested.Secondly,in order to achieve the goal of smaller size and higher switching frequency of the converter,planar transformer is utilized to replace the traditional transformer,the physical model of the leakage inductance and winding capacitance of the planar trans-former is established,the accuracy of the physical leakage inductance model is verified by the finite element simulation in four different printed circuit board(PCB)winding structure,a planar transformer with a high turn ratio of 1:10 is completed and a more op-timized design-not completely overlapped the winding structure for winding structure is gave out.Next,LCLC resonant converter is fully discussed.The resonant converter can realize zero voltage switching(ZVS)and zero current switching(ZCS)in the switching process of switching devices.The characteristics of the voltage gain,current gain and impedance characteristics of the LCLC resonant converter are analyzed,moreover,the characteristics of high-order resonant converters are analyzed and explored in detail from two aspects.On the one hand,combining the time domain and frequency domain analysis for the resonant circuit,and the two necessary conditions for the LCLC resonant converter working under the ZVS condition are given out?On the other hand,the transfer conditions between the high-order resonant converter and its low-order converter is discussed,by comparing with the 3rd order resonant converters LLC and LCC converters,the boundary between the 4th order resonant converter LCLC and the 3rd order resonant converter is obtained by means of numerical analysis.Finally,the properties of the LCLC resonant converter are verified through experiments.Finally,the inverter,the LCLC resonant converter,the transformer,and the rectifier circuit are comprehensively considered,and on the basis of expanding the existing theory,the equivalent model of high boost ratio DC/DC converter is established,which concludes the physical parameter such as voltage gain,power,resonant current,and equivalent load.The accuracy of the DC/DC converter model is verified through experiments and simu-lation.And after considering factors such as the soft switching condition of the resonant converter and the withstand voltage of the device,the design idea of the LCLC resonant converter is obtained.The theoretical analysis was verified by observing experimental waveforms and building a prototype,which achieved small size and high switching fre-quency with a high boost ratio of 1:100.