Research On Half-bridge LLC Resonant Converter Based On GaN Device

Modern power technology plays an important role in all aspects.High frequency,high efficiency,high power density,and miniaturization have become its current development trends and requirements.Switching devices and circuit topology are the main factors affect the above requirements.As a representative product of the third-generation power electronic devices,GaN devices are superior to traditional Si-based switching devices in terms of switching speed,device loss,reliability,and high temperature resistance.As a typical switching power supply topology,LLC resonant converter can realize soft switching technology and reduce switching loss.Firstly,study the electrical characteristics of GaN devices.The internal structure and conduction principle of GaN devices are theoretically studied,and compared with traditional Si MOSFETs.Combine the static characteristic parameters and dynamic characteristic parameters of specific Si MOSFET,Si C MOSFET and GaN devices for comparative analysis.Then the switching process of the GaN device is analyzed in detail,and the loss in the switching process is theoretically analyzed.Secondly,on the basis of clarifying the performance of GaN devices,this paper selects LLC resonant converter as the main circuit of the study.The working principle and working mode of LLC resonant converter at different switching frequencies are analyzed in detail.Use the fundamental wave analysis method to model the LLC resonant converter to obtain its equivalent circuit and DC voltage gain,and analyze the influencing factors of its DC voltage gain.In addition,the hardware circuit design of LLC resonant converter is carried out.The specific design method of resonance parameters is given and the calculation of resonance parameters is performed.Selection and design of transformer size,material and parameters.On this basis,the selection of main components is determined.The driving requirements of the selected GaN devices are analyzed in detail,and the driving circuit is designed.Finally,the simulation and prototype experiment research of LLC resonant converter based on GaN devices are carried out.The simulation results and physical results are consistent with the theoretical analysis,verifying the correctness of the calculated resonance parameters and the realization of the converter’s soft switching.Then analyze the main loss of LLC resonant converter,and the results show that applying GaN devices to LLC resonant converter can effectively reduce the loss.