Research On Life Prediction And Reliability Of SiC MOSFET Based On Physics Of Failure

With the increasing modernization of human society,how to face the energy crisis brought about by rapid development has become an urgent problem for all countries to be solved.As an industry with high consumption of non-renewable energy,fuel vehicle is the key breakthrough to solve the energy problem.Therefore,vigorously developing the renewable energy industry based on electric vehicles has become a common choice for all countries to solve the energy problem.Charging equipment is an important supporting facility for electric vehicles,and silicon carbide MOSFET,as a key vulnerable device of charging equipment,its life prediction and reliability analysis is an effective means to improve the stability of charging system.In the life prediction and reliability research of traditional power devices,the intermittent working state in practical application is ignored,and the changes of device thermal parameters caused by aging and ash deposition are not considered,which leads to a large error in the life prediction results of power devices.Therefore,taking the electric vehicle charging module as the application scenario,aiming at the life prediction error of silicon carbide MOSFET,the influence of the working state of charging equipment on the device life is fully considered.A flexible equivalent thermal model updated with device lifetime is constructed to describe the effect of aging and ash deposition on the lifetime of silicon carbide MOSFET.The life prediction and reliability analysis of silicon carbide MOSFET under different scenarios are carried out.The main research contents of this paper include the following aspects:The failure mechanism and failure mode of silicon carbide MOSFET are studied.In-depth analysis of the structure and working principle of silicon carbide MOSFET,to explore the fundamental mechanism of silicon carbide MOSFET fault.Summarize the failure mode of power devices,mine the index parameters that mark the failure of power devices,and study the internal relationship between failure index and failure process.The electrothermal model and life model of silicon carbide MOSFET are studied.Based on the VIENNA rectifier topology,the circuit loss model of silicon carbide MOSFET is constructed.The advantages and disadvantages of many kinds of thermal network models are analyzed,and the electrothermal coupling model of silicon carbide MOSFET is constructed.Compared with many classical life models,the conventional life prediction of silicon carbide MOSFET is carried out.The life prediction and reliability evaluation of silicon carbide MOSFET are studied.By using the thermal resistance increment of the device,the influence of aging and ash deposition on the life is quantified,and the equivalent thermal model updated with the device life consumption is constructed.The life prediction results of silicon carbide MOSFET in different scenarios are compared and analyzed,and the reliability of silicon carbide MOSFET is evaluated by using two-parameter Weibull distribution to fit the life samples of the device.This paper fully considers many factors that affect the life of silicon carbide MOSFET,improves the accuracy of life prediction and reliability evaluation of silicon carbide MOSFET,further enhances the stability and reliability of charging equipment,and has guiding significance for the intelligent operation and maintenance of charging equipment.