Research And Design Of The Key Circuit Of Drive Chip For Power-switching Devices

At present,as the representative of the-third-generation power-switching devices,IGBT has occupied more than half of the market of power-switching devices,which is progressing forward to high frequency,high power,low loss,easy driving,low cost.At the same time,the design of drive chip for them has become more and more important.Problems like overheating led by instable power supply,short-circuit failures,voltage overshoot if closed too fast always threaten the service life and reliability of power-switching devices.Therefore,how to optimize the structure of the drive circuit in order to ensure working reliability of the device and to further improve the switching frequency of the device,has become an important subject.This paper begins with the general situation and development trends of power-switching devices and their drive chips,the basic structure,working principle and electrical characteristics of IGBT.Then,based on actual performances of switching process of the IGBT module,possible risk points of its service life and reliability,the driving requirements of the IGBT module are summarized.At last,an IGBT drive chip is designed,which provides emergency protective measures on under-voltage and short-circuit,these two kinds of fault conditions,for 1200V/150 A IGBT module and below,under AEC-Q100 Grade1.It also uses soft turn-off method.First a small pull-current device discharges the IGBT gate charges,and then a large pull-current device quickly shuts down the IGBT,when the gate voltage drops to a low level,so as to improve the voltage overshoot problem during shutdown.This paper uses the BCD350 GE technology of Huahong,simulates and tests drive chip design in three kinds of situations like normal state,shortage of the chip power supply,IGBT's short-circuit,in AEC-Q100 Grade1.The worst situation is that,when the power supply falls,the drive chip can shut down the IGBT module completely in 1.1?s,when short-circuit occurs,in 6?s.The simulation results show that the drive chip makes the system's switching frequency up to 150 kHz under AEC-Q100 Grade1,and plays an effective role to improve the life and reliability of the IGBT module.