Analysis Of Oscillation During Switching Process And Application Design Of High-voltage And High-power GaN HEMT

Because of the excellent electrical characteristics such as high electron mobility,high saturation drift velocity and high critical breakdown electric field of GaN devices,it has great potential in the field of high voltage,high frequency and high power,and has been paid close attention.However,because of the low Rds_on of GaN devices and small high frequency loop area,the overall damping of high frequency loop is small.And with high switching speed of GaN devices which is up to 3000A/us,the oscillations of voltage and current are easily happened,especially in bridge structure,which make it difficult for high frequency application.So,the main research object of this paper is the oscillation phenomenon of high voltage and high power GaN devices in the bridge structure.Firstly,based on introducing the research background of GaN de-vices and the overseas and domestic research status of GaN devices,this paper summarized the research of GaN devices'characteristics and oscillation;Then based on the accurate test plateform,this paper tested the Cascode-mode and E-mode GaN devices,analyzed their dynamic characteristics and gave their mathematical models of switching loss.Using the test results,this paper analyzed the advantage and disadvantage of Cascode GaN device and E-mode GaN device;In view of the oscillatory occurrence,this paper analyzed the switching process of E-mode and Cascode GaN devices in combination with the dynamic characteristics test results.And then based on the switching process,this paper analyzed the oscillatory occurrence of GaN devices and gave two oscillation causes.In addition this paper gave 3 status of GaN devices after oscillatory occurrence;based on two oscillation causes,this paper respectively gave the restrain plans,and verified by simulation and experiment.Finally,this paper respectively built double pulse test plateform,Boost DC/DC plateform and dual Buck inverter AC/DC plateform in combination with dynamic characteristics test results and the restrain plans for application design of high voltage high power GaN devices.The experimental results verified the oscillation causes of GaN devices in the bridge structure and the effectiveness of the restrain plans;The experimental results verified importance of optimizion of high-frequency loop to applications of GaN devices;and at last,Using double pulse test plateform,this paper optimized the driving design.