Application Research On Cascode GaN Transistor And GaN Doide

The power electronic technology development of high frequency and high power density, switching power supply for power electronics device performance and reliability requirements are increasingly strict. Traditional silicon based power electronics power device has been increasingly close to limit determined by the physical properties of material theory. As a typical representative of the third generation of wide bandgap semiconductor materials, gallium nitride (GaN) has many more excellent physical properties than Si material, which is the excellent semiconductor material of high frequency, high temperature, high pressure and high power application of, and the market prospect of it is very broad. Since 2010, the research of GaN power device is becoming more and more significant. However, compared to the silicon carbide (SiC) power device, the research of characteristics and application of GaN power device is still in its preliminary stage and its device characteristics remains to be more deep and system research.This article mainly discusses the characteristics and applications of cascode GaN transistors and GaN diodes. Firstly this paper expounds the research background and development situation of GaN power devices. And then analysis the advantages and disadvantages and applicable occasions between monomer enhanced GaN transistor and cascode GaN transistor. Secondly based on the structure and the characteristics test of power device, this paper studies the static characteristic of Cascode GaN transistor and GaN diode and the corresponding mathematical models are given. Based on the equivalent circuit of cascode GaN transistor with parasitic parameters, this article detailedly analysis the the turn-on and turn-off dynamic process of cascode GaN transistor, and the mathematical models of their turn-on and turn-off loss are presented. The models are verified by simulation and experiment of the double pulse test circuit, and through the experimental prototype the reverse recovery characteristics of GaN and SiC diodes are tested. In order to improve the working reliability of the cascode GaN transistor, this article puts forward a suitable for high frequency occasions cascode GaN transistor overcurrent protection circuit, and its feasibility and effectiveness are verified by simulation and experiment. Finally, through the Buck converter and single phase full bridge inverter, the performance of cascode GaN transistors and GaN diodes are further assessed.The theoretical analysis, simulation and experiment of this article show that the high frequency characteristic of cascode GaN transistors is very excellent and the performance of GaN diode is as well as SiC diode.They are very suitable for high frequency, high power density of small and medium-sized power applications.