Study On A High Efficiency Converter Using GaN Device

The performance of Silicon device has been approaching its theoretical limit after 30 years of development,but switching power supply continues to develop to high-frequency,high power densit y and efficiency.As a representative of the third generation of semiconductors,Gallium Nitride(GaN)has many excellent properties that are not available in Si materials.There are some differenct characteristics between GaN device and Silicon MOSFET.Ai ming to high switching frequency and high efficiency,the application characteristics of GaN device in a two-stage DC/DC module converter will be researched.The optimization of driving circuit and efficiency will be studied.The development and current situation of GaN device are introduced firstly,and the advantages of GaN materials and devices are analyzed.The research hotspots and progresses of GaN devices are summarized.Then,a two-stage DC/DC module power supply based on EPC's GaN device is designed detailedly.The topology cinsisting of synchronous Buck and push-pull is selected,and switching frequency is 700 k Hz.The planar magnetic components and output filter is also designed.In this paper,the effect of stray inductance on high frequency drive circuit is studied in detail.A high frequency driving circuit is designed for the GaN device selected in this paper.The driving circuit and PCB layout is optimized.The loss of the magnetic components is calculated theoretically.The simulation results show that the loss of the GaN device is smaller than Si MOSFET.In addition,the mechanism of the push-pull soft-switch is analyzed,and the efficiency of the converter is improved by optimizing dead-time.The reverse conduction loss of GaN device is also analyzed,and the effectiveness of the optimization measure is verified by experiments.After the theoretical design,a 450 W full-brick eight-layer structure prototype is fabricated,and the efficiency is up to 95.05%.The paper also tests the prototype at 500 k Hz and 340 k Hz switching frequency.The experimenta l results show that the GaN device has a significant advantage over the Si device in improving the switching frequency and efficiency,and has an excellent prospect in engineering applications.