Design Of A High-efficiency GaN-Based DC/DC Switching Power Supply

As an important technology in the field of power electronics,direct current conversion technology(DC/DC,Direct Current/Direct Current)has been widely concerned by researchers.The current DC/DC switching power supply mainly uses Si(Silicon)devices as switching devices,but due to the limitation of material performance,the power loss of Si-based DC/DC is large,and the energy conversion efficiency of the system is low,especially at high frequencies.Compared with Si devices,GaN(Gallium Nitride)power devices have the advantages of low on-resistance and small parasitic capacitance,which can be better applied to high-frequency and efficient switching power supply applications.Therefore,this paper aims at the problem of large power loss and low conversion efficiency of Si-based DC/DC,using the performance advantages of GaN devices,based on the mature power conversion system design theory,through the calculation-simulation-test process,to developed a high-frequency,high-efficiency GaN-based DC/DC switching power supply,and studied the application characteristics of GaN devices in DC/DC modules.First of all,this thesis starts from the theoretical perspective of power semiconductor devices and conducts in-depth research on the physical characteristics of GaN devices,through the comparison of main performance parameters and their influencing factors,the advantages and disadvantages of GaN power devices compared with traditional Si devices in switching power supplies are analyzed.Secondly,according to the design index from practical application,the power consumption analysis of key components such as switch tube,output inductance,input capacitance and output capacitance in the switching power supply is carried out,and the design selection is carried out based on theoretical analysis.In addition,for the GaN power device in the converter is sensitive to the dead time,power loop drive loop parasitic parameters and other issues,the introduction of adjustable dead time drive circuit,the use of vertical power loop layout and other solutions to improve the above problems,thereby further Improve the conversion efficiency of the DC/DC switching power supply.After the completion of the above work,the simulation of the circuit was carried out.In order to highlight the performance advantages of this design,the Si-based DC/DC under the same index was also simulated and compared with this design.Finally,build and test 84-50 V step-down GaN-based DC/DC switching power supply.When the output power of the prototype is 75 W and the operating frequency is >1MHz,the full load efficiency is 95.3%,which is at least about 4% higher than that of the Si based converter of the same magnitude.The test results on the one hand illustrate the rationality of the theoretical analysis and design process,on the other hand,illustrate the great potential of GaN devices in high-frequency,high-efficiency switching power supply applications.