Research On Protection Technology And Oscillation Of SiC MOSFET

With the gradual commercialization of third-generation semiconductors,the replacement of silicon-based power devices has become a trend in the future.The good high temperature,high voltage and high switching speed characteristics of SiC MOSFETs have become the main force to replace Si IGBTs and Si MOSFETs,increasing the power density of power electronics equipment and greatly reducing losses.This article has designed the drive circuit of SiC MOSFET power module(CAS300M17BM2).The designed drive circuit has the functions of isolation,power amplification,short-circuit protection,soft turn-off,under-voltage protection,dead-zone and interlock,and uses CPLD for signal processing.And troubleshooting.The principle of double-pulse test is analyzed in detail,which provides a scheme for accurately measuring the switching transient process of a switching device at a specific voltage and current level.A low-parasitic dual-pulse platform for SiC MOSFETs for low-power packaging was designed.The short-circuit protection detection scheme based on the saturation voltage drop is simple and reliable.When applied to the protection of SiC MOSFETs,the principle and the parameter selection are analyzed in detail,so that the short circuit protection delay is greatly reduced.The active clamp scheme was studied,and an active clamp circuit for SiC MOSFET was proposed to prevent the secondary turn-on after the short-circuit turn-off.The effect of the snubber capacitor when the short circuit turned off was analyzed.A soft turn-off scheme was discussed and a two-stage drive voltage shutdown scheme was used.Taking a half-bridge circuit as an example,the influence of parasitic parameters is analyzed.During the switching process,the voltage oscillation caused by the parasitic parameters in the power loop establishes the model and quantitative analysis to study the overvoltage of the switch tube when the switching speed is on.Influence to ensure that the overshoot voltage is reduced as much as possible without affecting the switching performance.The oscillation of the drive circuit was explored.The common parts of the drive circuit and the power circuit brought about a great impact on the grid oscillation.The mechanism was analyzed qualitatively and the suppression measures were proposed.