Design Of IGBT With Integrated Current Sensor And Protection

Since commercialization,IGBT?Insulated-Gated Bipolar Transistor?has been widely used in power electronic systems,especially medium and high power equipment,such as variable speed motor control,wind power generation,and new energy vehicles.As a key component of automatic control and power conversion,it has always been moving toward higher reliability.The over-current protection has been one of the focus on the problem of IGBT application.At present,current sensors with higher accuracy for IGBTs often use the principle of mutual inductance,which has the problems of large size and high price.Thus,this thesis aims to designs a 1200V/40A planar FS-IGBT with integrated current sampling function,which is mainly used in IGBT modules with higher integration and reliability.In order to reduce the on-state voltage of the IGBT,a CS?Carrier Store?layer is added.In addition,this design also provides an overcurrent protection circuit scheme for this IGBT.This thesis first describes the theory of IGBT operation,analyzes and introduces the safe working area of IGBT and the overcurrent protection method for IGBT.Secondly,based on the process conditions,the process flow of FS-IGBT compatible with that of the integrated current sensor is develop,and the simulation process is used to analyze and optimize the process parameters of the IGBT,including the simulation analysis of the relationship between the breakdown voltage of the device and the parameters of Ndrift,the relationship between P-base region process and static electrical parameters,the effect of backside process of IGBT on turn-off characteristics and on-state voltage,and the effect of cell width and Poly pitch on IGBT electrical parameters.On the basis of the designed IGBT,the reasons for the deviation of the current of the conventional sampling structure are analyzed.This thesis analyses the influence of circuit parameters and IGBT structure parameters on sampling.The results show that:first,to reduce the trigger voltage and increase the overcurrent value can improve the linearity of the sampling current,it is also can alleviate the sampling current overshoot phenomenon;second,the sampling cell with isolation structure and high threshold voltage can suppress the sampling current overshoot phenomenon.Finally,completing the layout drawing with L-edit software,the design scheme of overcurrent protection circuit is proposed.The optimized IGBT cell has a breakdown voltage of 1420V,an on-state voltage of2.1V,and a threshold of 5.7V.The sampling cell has a breakdown voltage of 1441V,an on-state voltage of 2.24V,and a threshold of 6.8V.The designed IGBT has a short-circuit capability exceeding 10?s,a short-circuit current of 177A,and a V_CEsat with a positive temperature coefficient at rated current 40A.The sampling structure can suppress the overshoot of the sampling current during it switching.The protection circuit implements a protection behavior when the IGBT overcurrent time exceeds 3?s or a short circuit occurs.