Temperature Rise Estimation Of SiC Power MOSFET Based On Model

Silicon carbide power MOSFET has the advantages of high temperature and high voltage resistance of wide band gap devices,small drive loss and short switching time,which can ensure good working characteristics and high stability,and meet the increasing requirements of energy density,working efficiency,energy conservation and environmental protection of electric electronic equipment in automobile,power supply,aerospace and other systems,Therefore,it becomes more and more popular in research and application.However,at high switching frequency,silicon carbide power MOSFET may produce oscillation,overvoltage and overcurrent,which will cause huge switching loss,increase device temperature,affect device performance and even cause device failure.Therefore,it is of great significance to study its working characteristics and estimate its temperature rise by modeling its characteristics and transient analysis.Based on this,this paper focuses on the following work of SCT30N120 silicon carbide power MOSFET produced by ST company:Firstly,the static model of SiC power MOSFET is established.The understanding of the working principle of the device and the accurate measurement of the device performance are the basis of modeling analysis and temperature rise estimation of the device.In order to obtain the static characteristics of the device,a high-temperature test platform based on B1505 A power semiconductor tester was built.The SCT30N120 was tested,and its output characteristics,transfer characteristics,on state resistance,threshold voltage,parasitic capacitance and other parameter curves in a wide temperature range were obtained.The curve fitting modeling was carried out to establish the basis for the subsequent accurate fitting of dynamic characteristics.Secondly,the transient process of the switch is modeled and simulated.The simplified circuit model is established and the transient process of silicon carbide power MOSFET switch is analyzed.The state equation is solved by MATLAB.The dynamic model is based on the experimental results to consider the temperature characteristics of threshold voltage,on resistance and the nonlinear characteristics of parasitic capacitance.Through this modeling method,the parasitic inductance and drive resistance can be changed,and the influence of parasitic parameters and drive circuit settings on the switching process can be studied;the influence of temperature on threshold voltage,on resistance and other parameters can be considered,and the temperature can be set to study the influence of temperature on the switching transient.Thirdly,through the finite element modeling method,based on the internal micro physical structure of silicon carbide power MOSFET,the device finite element model is established and the temperature rise of each part is calculated to estimate the maximum allowable power of the chip.In addition,the thermal stress is analyzed by changing the heat dissipation conditions and working conditions.Based on the established model and the definition of chip thermal resistance,the thermal resistance is calculated;the transient response curve of device temperature is obtained by transient simulation,and the thermal resistance network model is proposed,based on which the chip temperature rise can be estimated.Finally,through simulation,the influence of changing the driving resistance on the device loss and switching behavior is studied.Based on the established thermal resistance network model,the transient simulation experiment is carried out to study the temperature rise of the device.