Research On Digital Driving And Protection Circuit Of Medium And High Power SiC MOSFET Module

With the development of power electronics technology,traditional devices based on Si have gradually approached their physical limits,So the third generation of wide bandgap power semiconductor devices represented by SiC MOSFET emerged.As a new device,the driving and protection technology of SiC MOSFET have to be developed in the future.Therefore,reliable and efficient research on SiC MOSFET driving and protection technology is extremely important.First of all,the basic physical structure,switching characteristics and main technical parameters of SiC MOSFET are introduced,and the key parameters of SiC MOSFTE driver design are analyzed in detail.Secondly,the structure,advantages and disadvantages of traditional driving circuit are analyzed in detail,on this basis,a digital driving and protection circuit of SiC MOSFET based on FPGA is designed,variable gate drive voltage V_GS and gate drive resistance R_G are realized.Combining with the switching characteristics of SiC MOSFET,the control strategy and working principle of digital driving scheme are analyzed in detail.Finally,the common types of short circuit faults of SiC MOSFET are analyzed,short circuit detection methods,V_DS desaturation and dI_D/dt detection,and their circuit design are introduced in detail.The overvoltage of SiC MOSFET,the type of undervoltage of driver and the design of protection circuit are analyzed.In order to verify the reliability and superiority of the designed driving and protection circuit,a double pulse and short circuit test platform was built,based on this,the effects of driving circuit parameters such as R_G and V_GS on the switching characteristics of SiC MOSFET are analyzed in detail.According to the contrast experiment,compared to conventional driving circuit,the digital driving Scheme for variable V_GS and R_G can effectively control the drain current slope d I_D/dt and the drain source voltage slope dV_DS/dt during the switching process,which can reduce current and voltage spikes and suppress switching oscillations,while increasing the switching speed,the current and voltage spikes can be reduced and the switching oscillation can be suppressed.And through the V_DSS desaturation protection circuit,based on the study of the short circuit characteristics of SiC MOSFET,turn-off the device with two kinds of soft turn-off methods falling gate voltage and large resistance,its superiority in reducing turn-off voltage overshoot and improving short circuit characteristics is verified,and the V_DS desaturation detection blank time(T_blank)and soft turn-off time(T_soft)are adjustable digitally,the advantages of digital driving and protection circuit are brought into full play.