基于隧道磁电阻TMR的SiC MOSFET模块短路和过流保护技术

由于碳化硅MOSFET的短路故障电流上升速度快、峰值大，短路承受时间远低于硅IGBT，且过流时门极栅氧层易老化，碳化硅MOSFET要求更为快速可靠的保护技术。本项目提出基于隧道磁电阻TMR的碳化硅MOSFET短路和过流保护技术，设计并制备集成TMR传感器和保护功能的碳化硅MOSFET模块。作为新型传感器，TMR阻值随周围磁场而变化，构建桥式电路即可测量电流，由于无需积分器，可以测量直流及缓变电流，使得短路和过流检测更为快速可靠。本项目首先研究最适宜碳化硅MOSFET电流检测的TMR测量电路；研究基于TMR的碳化硅MOSFET过流及短路检测技术，使故障检测和保护时间分别小于500ns和1μs；最后研究TMR传感器在碳化硅MOSFET模块内部的布局与屏蔽技术，制备集成TMR的碳化硅MOSFET模块。本项目将提供一种可靠、快速的碳化硅MOSFET短路保护技术，为碳化硅器件的大规模应用提供支撑。

Compared to Si IGBT, the short-circuit faulty current of a SiC MOSFET has a much faster rising rate and a higher peak value, and the short-circuit withstand time (SCWT) of a SiC MOSFET is much shorter. In addition, the gate oxide of a SiC MOSFET can degrade after over current faults, leading to leakage current at the gate electrode. This project proposes a short-circuit and over-current protection scheme based on the tunnel magnetoresistance (TMR), designs and constructs a SiC MOSFET module integrated with TMR sensors and corresponding protection scheme. As a new type of current sensor, the resistance of TMR changes with the external magnetic field, and current can be measured using a bridge circuit composed of TMRs. Due to the elimination of the integrator, the current measurement based on TMRs can sense the current with low di/dt and dc current, enabling a more reliable and faster short-circuit fault detection in a SiC MOSFET. This project will firstly study different types of TMR circuit for current measurement of SiC MOSFET and find the most suitable one for SiC MOSFET fault detection; then based on the current measured by TMR, over-current and short-circuit protection for SiC MOSFET will be studied to achieve detection and protection time less than 500ns and 1μs respectively; finally the layout of the TMR sensors as well as its shielding technique will be studied in a SiC MOSFET module, and a SiC MOSFET module with integrated TMR current measurement sensors will be constructed. This project will provide a reliable and fast short-circuit and over-current protection method for SiC MOSFET modules to boost their applications.