Modeling And Analysis Of Multi-Time Scale Dynamic Characteristic Of IGBT Power Electronic Systems

With the rapid advancement in power electronic devices and power electronics technology,the switching frequency and power density of an Insulated Gate Bipolar Transistor(IGBT)are becoming higher and higher,resulting in a large di/dt of its output current.Also,the time scale of its dynamic characteristics varies from a milli-second level to a micro-second level,and even to a nano-second level,featuring a small.time seal transient electromagnetic characteristics.To consider the effect of the displacement current and the skin effect of the electromagnetic phenomenon as well the stray parameters in a small time scale electromagnetic transient,which are not properly modeled in the available models,a coupled 3D finite element-circuit model of an IGBT based power electronics device for its transient performance computation in small and extreme small time scales is developed,and an iterative solution methodology is proposed.In order to describe the skin effect and displacement current,a three-dimensional(3D)finite element model of IGBT is developed;In order to model the influence of stray parameters,a high-order distributed circuit model of the whole power electronic system is proposed,and the numerical method to evaluate the stray parameters is developed.Based on the analysis of the internal electromagnetic transient process of an IGBT,an improved IGBT circuit model is proposed.In order to balance the solution accuracy and the computational cost of the high order circuit model of a complete power electronics system,a oeder reduced method is proposed.The comparisons between the simulated and tested results validate the feasibilities and merits of the proposed work.Moreover,as the power density and switching speed of IGBTs is continuously increased,an IGBT will produce considerable amount of switching and conducting losses,affecting its performance and safety operations.Therefore,a coupled 3D eddry current-temperature transient model is proposed,and its accuracy and merit are verified by the numerical and experimental results in a case study.