Research On Characteristics And Application Of Cascode GaN Power Devices

Cascode GaN power devices have gradually been commercialized,they have shown superior performance in terms of withstand voltage,switching performance,and temperature characteristics compared to traditional silicon materials.However,there are still some problems in driving,oscillation suppression,packaging and reliability.To a certain extent,which have affected the rapid promotion and application of Cascode GaN power devices.In order to promote Cascode GaN power devices to exert their performance advantages and realize the replacement of silicon devices,the paper did the following work:The paper first introduces the development and research status of GaN power devices at home and abroad,as well as the materials,structure and static electrical characteristics of GaN devices.Summarizes the performance advantages and disadvantages of the two GaN device structures,Cascode and E-mode.The main research object is the Cascode GaN power devices of Dalian Xinguan Company,taking the dual pulse circuit as the test background,the dynamic characteristics of Cascode GaN power devices are analyzed in detail,and built a simulation circuit and experimental platform to verify.To more accurately understand the switching process of Cascode power GaN devices,an external cascade GaN power device was built,the respective switching behaviors of depletion-mode GaN tubes and low-voltage Si MOS tubes during the switching process were analyzed.And the key equations of each stage and the device loss calculation model better than the classic loss calculation method are given.The voltage and current oscillations generated are the main factors affecting its high-frequency application and reliability during the switching process.The paper studies the drive circuit for high-speed applications of Cascode GaN power devices,and evaluates the effect of magnetic beads on switching characteristics.In addition,the oscillation mechanism of the switching process and the Miller platform stage is analyzed,and the specific oscillation suppression methods are provided accordingly,including:reducing the switching speed,reducing the common source parasitic inductance,selecting the appropriate driving resistance,and optimizing the layout and designing oscillation absorption circuits.Finally,the paper selected the synchronous Buck and full-bridge LLC resonant converter as the research topology for the application characteristics of Cascode GaN power devices,and used the original Spice device model provided by the manufacturer to simulate and verify according to the designed parameters,two prototypes of Buck-2500W and full-bridge LLC-2000W were built.The advantages of Cascode GaN power devices are summarized,and specific application optimization and solutions are given.The experimental results further verify the excellent switching characteristics of Cascode GaN power devices,they can be applied to hard switching and soft switching topologies.