Research On Junction Temperature Extraction And Short Circuit Protection Of High Power SiC MOSFET Module

In recent years,power semiconductor devices such as IGBT and MOSFET have been widely used in many industrial fields,especially in fields requiring high reliability such as wind power generation,automobiles and aerospace.Therefore,reliability issues have become the focus of increasing attention,especially novel applications of wideband gap?WBG?devices,such as silicon carbide?Si C?power MOSFET and other high electron mobility transistors.They can significantly improve power density and conversion efficiency,but due to the lack of production processes,especially the gate oxide layer is not the stability which make the reliability of Si C MOSFETs challenged.The good thermal management and fast short-circuit protection can significantly improve the reliability of Si C MOSFETs.Therefore,this paper studies the high power Si C MOSFET module from two aspects:online junction temperature extraction and short circuit protection.This article first theoretically analyzes the working principle of Si C MOSFET and the switching transient process,and establishes a mathematical model for the electrical parameters.The one-to-one correspondence between junction temperature and drain current change rate is found in the model,and the gate charge and drain current are the same relationship.Subsequently,the principle of the double-pulse experiment is introduced,and the double-pulse experiment platform is built.The experiment confirmes that the d I_DS/dt increases with the increase of the junction temperature.Then the experiment analyzes the influence of other parameters on the d I_DS/dt.A small driving voltage V_GG and a large gate resistance R_G-extcan improve the temperature sensitivity of d I_DS/dt.Finally,a Si C MOSFET online junction temperature extraction circuit based on a PCB coil is designed.Experimental results show that the method is feasible.Its resolution is 4m V/?.Many works have studied the short-circuit mechanism of Si C MOSFET,but the design of short-circuit and over-current protection for high-power Si C MOSFET modules is still small,and most of them still use the IGBT short-circuit protection circuits.For the research of short-circuit protection,firstly,the different gate charge changes of Si C MOSFET under the conditions of hard short-circuit fault HSF,load fault FUL and overcurrent fault OCF are analyzed,and a short circuit protection circuit based on gate charge is designed in combination with intelligent driving Then,the hardware of the circuit and the short-circuit detection process are introduced in detail.The experiment analyzes the interference of other factors on the gate charge.It is found that the gate charge hardly changes with the bus voltage,but increases with the increase of junction temperature.Finally,the three short-circuit faults are experimentally verified.The results show that the protection method can safely shut down the device within 2?s,and the shutdown voltage spike is very low.There are 54 figures,2 tables and 88 references in this thesis.