Pspice Modeling And Validation Of Silicon Carbide BJT

Silicon Carbide Bpolar junction transistor(SiC BJT)shows not only shorter reverse recovery time,lower on-resistance,high switching speed than Silicon Bipolar junction transistor(Si BJT),but also simpler process,lower cost and no gate oxygen problem than SiC MOSFET due to SiC material superior properties,for instance the wide bandgap,high critical breakdown electric field and high thermal conductivity.Thus,it can satisfy the strict demands of power semiconductor devices proposed by power electronics technology,and it has already been widely used in electric power electronic transformation system.However,the current gain degradation caused by the external base region recombination effect of SiC BJT affects the reliability of the devices seriously.At the same time,the equivalent circuit simulation model of SiC BJT determined the accuracy of simulation results in the process of aided design system with simulator,but the SGP model of Si BJT cannot describe the external base region recombination effect of SiC BJT.Therefore,it is urgent to establish an accurate and reliable behavior model of SiC BJT to evaluate the performance index of system power consumption and efficiency,so as to predict the performance of the system and design the cooling system.This paper presents an improved BJT model—SGP1 model,which not only solves the problem that SGP model can't describe SiC BJT's base surface recombination current,but also describes the SiC BJT's electrical characteristics accurately.Firstly,this paper simplifies the topology of SGP model and some model parameters by comparing the structure and working principle of Si BJT and SiC BJT,and modifies some model parameter default values according to the different concentration of dopant in the base region.Then,taking the external base region recombination effect of SiC BJT into account and model this effect,namely using the theory that BJT device's surface recombination current is a exponential function of base emitter junction voltage,and by paralleling a diode across the emitter junction in intrinsic SGP model,current flows through the diode represents the base surface recombination current.Finally,using the Power Device Analyzer Agilent B1505A to measure the static characteristic curves and C-V curves and the double pulse measurement circuit to measure the switching characteristic curves.Imported the measurement datas into the Origin to extract the SGP1 model parameters with the optimized fitting method.In the LTspice circuit simulation software,the static and dynamic equivalent simulation circuits of SiC BJT are constructed,and the electrical characteristics of SiC BJT are simulated with the SGP model and SGP1 model respectively.The comparison of simulation results and measurement results shows that the SGP1 model can describe the electrical characteristics of SiC BJT more accurately.The SGP model proposed in this paper not only simulates the external base region recombination effect but also describes the static and dynamic characteristics of SiC BJT.In order to have a better application the SGP1 model,the SiC BJT based Boost-Chopper circuits are constructed in LTspice.Using SGP1 model to describe the electrical characteristics of SiC BJT,compared the simulation results with the results of the adaptive drive for SiC BJT,and the calculated driving power consumption,comparison results also validate the validity,accuracy and reliability of the BJT SGP1 model of SiC BJT.