Research On Application Of Silicon Carbide MOSFET In Half-bridge LLC Resonant Converter

With the rapid development of switching power supplies in our country,LLC resonant converters are becoming more and more favored by researchers as the back-stage circuit for connecting electrical equipment.LLC resonant converters are also gradually undergoing transformation and upgrading of high power density,high frequency and high efficiency.However,traditional silicon(Si)devices cannot meet practical application requirements due to their material characteristics.In contrast,the third-generation semiconductor devices represented by silicon carbide(SiC)devices have low switching losses and high withstand voltage,High thermal conductivity and other advantages,can achieve the high power density and high efficiency requirements of the converter design.Therefore,this article has carried out the research of half-bridge LLC resonant converter based on SiC MOSFET.This article first explores the channel structure,static and dynamic characteristics of SiC MOSFET,and analyzes the requirements of SiC MOSFET for driving circuit voltage based on its characteristics.Then according to the analysis of different topological structures of LLC resonant converter,a half-bridge LLC resonant converter is selected as the research circuit of this article.Analyze the fundamental equivalent circuit of LLC resonant converter,study the working principle of LLC resonant converter,analyze the influence of quality factor and inductance on gain according to the DC voltage gain characteristics,put forward a reliable parameter design plan and calculate the parameters.Secondly,the loss components of the converter are analyzed,and the digital control system of the converter is designed.Carried out the design of SiC MOSFET drive circuit,control circuit and sampling circuit,drawn the corresponding hardware circuit schematic diagram,and tested the reliability of the drive circuit.Finally,use MATLAB/Simulink software to simulate and verify the designed converter,and build an experimental prototype.The simulation and experimental results verify the feasibility of the parameter design scheme and the digital control system.Research has proved that the converter can stabilize output and has good efficiency.