Research On Active Gate Driver And Fast Short Circuit Protection Of SiC MOSFET Module

The development and transformation of electrified transportation,energy Internet,and 5G mobile communications have put forward higher requirements for power electronic equipment,such as higher efficiency,higher power density,and higher reliability.However,the performance of existing silicon-based power semiconductor devices is difficult to meet the growing development needs.Silicon carbide(SiC)MOSFET has excellent characteristics such as high switching speed,low conduction loss,and high thermal conductivity,will become the core device of high power,high efficiency,high power density converters,and has broad application prospects.However,SiC MOSFETs face the problems of voltage and current overshoot,high-frequency oscillation caused by the high-speed switching process,and low short-circuit tolerance,which seriously threaten the reliable operation of SiC-based converters.In order to achieve high efficiency,low electrical stress driving and safe and reliable operation of SiC MOSFET,this thesis first analyzes the working principle and characteristics of SiC MOSFET,studies the switching process and switching trajectory of SiC MOSFET under inductive load conditions.The mechanism of voltage and current overshoot and oscillation in MOSFET switching process and the influence of driving parameters on swi tching transients are analyzed in detail.Then the LTspic simulation model of the CREE CAS300M12BM2 half-bridge module with detailed parasitic parameters was built,Finally,the regulation of driving parameters on the switching characteristics was studied,which provided a useful reference for the design of active gate driver.There are some problems in the conventional gate driver and the existing active gate deiver in the literature,such as the overshoot suppression effect and the loss are difficult to optimize at the same time,and the implementation is complex.An active gate driver for SiC MOSFET with segmented dynamic adjustment of drive current was proposed in this thesis,which dynamically adjusted the gate drive current of the power device according to the feedback of different stages of the switching process.Experimental results show that the proposed gate driver can suppress the voltage and current overshoot and high frequency oscillation of during the switching process of SiC MOSFET while maintain low switching losses,and reduce the high frequency electromagnetic interference emission during the switching process.SiC MOSFET is faced with higher risk of short-circuit failure in application,and its short-circuit protection needs faster response s peed and higher reliability.This thesis proposes two short-circuit fault detection methods for SiC MOSFET module.ased on the analysis of the difference of instantaneous power consumption between normal switching process and short-circuit fault condition of SiC MOSFET,a short-circuit protection strategy based on device instantaneous power consumption detection is proposed.There is no detection blind zone in the strategy,and the more serious the short-circuit fault is,the faster the protection response is;ased on the analysis of the difference of instantaneous power consumption between normal switching process and short-circuit fault condition of SiC MOSFET,a short-circuit protection strategy based on device instantaneous power consumption detection is proposed.There is no detection blind zone in the strategy,and the more serious the short-circuit fault is,the faster the protection response is;Simulation results show that the proposed composite short-circuit protection method has higher reliability and response speed than the conventional single method,and can better ensure the safe operation of the device.