Nonlinear Modeling And Application Of Silicon Carbide Power Device

Silicon carbide(SiC)materials have attracted much attention because of its wide bandgap,high critical electric field and high thermal conductivity and other characteristics.In recent years,commercialized SiC power devices have been introduced successively,but the reliability problem is one of the bottleneck restricting their development.As we all know,the reliability of the device is mainly affected by the transient nonlinear behavior such as high temperature and high electric field,which leads to the degradation of internal parameters and external electrical characteristics of the device,and thereby reducing device reliability and service life.In order to reveal the intrinsic relationship between the transient nonlinear behavior of the SiC power device and its physical parameters,it is necessary to describe it by the exact device model.However,the existing SiC power device model is mostly linear model and does not consider real-time effect of temperature variation on its physical parameters,resulting in simulation accuracy has some limitations.Therefore,the nonlinear modeling of SiC power devices has great significance to improve its reliability and service life.Based on the mechanism of SiC power device,nonlinear modeling of SiC MOSFET and Si C BJT.Presenting a modeling method based on Haar wavelet mathod for SiC BJT,and a modeling method based on time-varying temperature feedback for SiC MOSFET,a nonlinear simulation model of SiC power device is established to facilitate the in-depth study on the transient nonlinear behavior of the device.This paper mainly carried out the following research work:(1)Aim at solve the accuracy problem of bipolar diffusion equation(ADE),present a modeling method based on Haar wavelet mathod for Si C BJT.From the mechanism analysis of SiC BJT,using the semiconductor physics theory analysis the internal dynamic behavior and the current-voltage relationship.The Haar wavelet method is applied to solve the ADE.Simulation results are compared with Fourier series method,and show that the Haar wavelet method can improve the accuracy of the solution of the physical model.(2)Present a modeling method based on time-varying temperature feedback for SiC MOSFET.From the mechanism analysis of Si C MOSFET,think about of the relationship between SiC MOSFET module,thermal network module and power loss module,and the power loss and thermal network module are introduced into modeling to feedback junction temperature and update real-time parameters,and which reflect the process of conduction and switching characteristics of SiC MOSFET more reasonable.The simulation results proved the rationality of the modeling method.(3)Experiment with the electric-thermal coupling model of SiC MOSFET.Use the Si C MOSFET in E-type inverter,design the driving circuit and build the experimental module.The device of SiC MOSFET adopts CREE C2M0160120 D,and the experimental results proved the rationality of the modeling method.