Research On Silicon Carbide MOSFET Transient Switching Process Modeling

Since silicon carbide(SiC),gallium nitride(GaN)and other wide-bandgap semiconductor devices have excellent electrical and thermal properties,they are very suitable for high-voltage,high-temperature and high-frequency applications.Hence,in recent years,these new devices are gradually replacing traditional silicon devices in power electronic converters,which improve the power density and efficiency of power electronic devices significantly.Therefore,these novel devices have been widely used in rail transit,new energy vehicles,and aviation.Aerospace and other transportation and industrial automation fields.However,novel devices not only bring excellent performance,but also bring huge design and application challenges in the practical application when it comes to replace traditional silicon devices.During the application process,due to the fast switching speed of the device,that is,extremely fast di/dt and dv/dt,this characteristic requires the device package with lower parasitic inductance,which significantly affects the characteristics of the device.The design steps based on traditional devices often need to complete related design work such as device selection,topology selection and design,loss calculation,thermal design evaluation,etc.The design process based on wide bandgap semiconductor devices is similar,but traditional loss calculation models and methods introduce large errors when applied to silicon carbide devices.The errors are mainly derived from the switching loss calculation results of the traditional model.Traditional model cannot be applied to the design of power electronic devices based on wide bandgap semiconductor devices suitable for high-frequency applications.Therefore,one of the challenges in the design process is the need for a new type of switching loss calculation model that can accurately calculate the switching loss of silicon carbide devices.Therefore,this paper researches on modeling study based on the switching transient process of silicon carbide MOSFET,aiming to propose a high-accuracy switching loss calculation model for the silicon carbide MOSFET.This article first analyzes the traditional switching loss calculation model and the source of error when it is applied to the silicon carbide MOSFET,and summarizes the improved methods and advantages and disadvantages of the existing literature to solve these problems.In the third part,a switching loss calculation model suitable for silicon carbide MOSFETs is proposed.This model takes into account the parasitic inductance of the device,the nonlinearity of the junction capacitance of the device and the nonlinearity of the transconductance.The fourth part verifies the accuracy of the model through the comparison of simulation and experiment.The experimental results show that the proposed model has high accuracy in calculating the switching loss of the silicon carbide MOSFET,and the loss calculation error in the turn-on transient process is only 6%,The loss calculation error of the turn-off transient process is 18%.Compared with the most accurate calculation model in the existing literature,the accuracy of the switching loss proposed in this paper is improved by at least 36%.