SiC MOSFET Driver Circuit Research And Design

With the continuous improvement of the performance requirements of power electronic conversion devices in the application fields of smart grid,electric traction,electric vehicles,etc.,the power electronic devices in various conversion devices are moving toward high withstand voltage,high current density,high switching frequency,and low conductivity.Development in the direction of pressure drop.SiC power devices have the characteristics of high withstand voltage,high temperature resistance,high switching frequency,etc.,making them a better choice for power electronic converters instead of Si devices.In actual application scenarios,the increase in switching frequency and switching speed of SiC MOSFETs will cause problems such as excessive voltage and current spikes,oscillation,crosstalk,and electromagnetic interference.Therefore,in order to make SiC MOSFETs safer and more reliable to operate in power electronic conversion devices,Voltage and current spikes,oscillations,crosstalk problems and drive protection circuit:First,a detailed comparison of the conduction characteristics,blocking characteristics,switching characteristics and driving characteristics of SiC MOSFETs is compared with Si MOSFETs.Based on the analysis of the above basic characteristics,the basic requirements and precautions for the design of SiC MOSFET drive circuit,and the design of the SiC MOSFET drive circuit.Under the application background of high-speed switching of SiC MOSFET devices,the influence of parasitic inductance in the circuit can no longer be ignored.Based on the dual-pulse test circuit platform with parasitic inductance,the driving performance of the designed driving circuit is verified and compared on this basis The dynamic characteristics of SiC MOSFET and Si MOSFET are studied,highlighting the advantages of SiC MOSFET.Then,consider the problems of excessive voltage and current spikes,oscillation and crosstalk in the switching process when SiC MOSFETs exert high-frequency characteristics in practical applications.To this end,the basic principles of its generation are analyzed,and the current common methods for suppressing voltage and current spikes,oscillations,and crosstalk are different from the new suppression methods.On the basis of sacrificing less SiC MOSFET switching losses,an improvement is proposed.The auxiliary branch of the drive circuit has completed the design of the auxiliary branch and calculation of related parameters,thereby providing a basis for the high-speed switching application of SiC MOSFET devices.Finally,on the built-up double-pulse test platform,the performance of the designed improved active drive circuit is verified by experiments on voltage and current spikes,oscillation problems and crosstalk problems.After comparing the traditional RCD absorption circuit with a typical active drive circuit,the improved active drive circuit designed in this paper can effectively suppress the voltage and current spikes and oscillation problems while reducing the complexity of the drive circuit.At the same time,compared with passive suppression and active crosstalk suppression methods,the improved active drive circuit designed in this paper effectively suppresses the bridge crosstalk problem at the expense of less switching loss.Finally,a synchronous Buck converter was built,which verified the drive protection performance of the active drive protection circuit designed in this paper in actual application scenarios.At the same time,with the improvement of the active drive circuit,the conversion efficiency of the synchronous Buck converter increased by 0.27%.