Research On The Lumped-charge Model And Parallel Modeling Of High Power IGBTs

With the development of power electronics technology and power semiconductor device,a lot of power electronic equipment are used in the fields of new energy,electromagnetic emission,aerospace,high-speed rail,ship propulsion,and power transmission,which require energy conversion.As the most widely used power electronic switching device in large-capacity power electronic system,IGBT(Insulated Gate Bipolar Transistor)power module's working characteristics are also widely concerned by device manufacturers and power electronics system designers.Establishing a model that accurately describes the IGBT's operating characteristics can better help researchers understand the operating characteristics of IGBTs under different operating conditions(on-state,off-state,switching transients,etc.),thus guiding device manufacturing and the research and design of power electronics equipment.It has always been a difficult problem for researchers to choose the appropriate IGBT physical model based on the studied problems and objects.Because of there is no systematic summary of the relationship and difference among many existing physical IGBT models,including their respective advantages and disadvantages,this paper proposes that IGBT models can be divided into four categories according to the different mathematical methods used in the models: shape function model,space transformation model,time transformation model,and the lumped-charge model.This classification method can provide theoretical guidance for the research and selection of physical modeling methods for IGBT.For the purpose of physical modeling of high-power IGBTs and their parallel combination modeling research,the lumped-charge modeling method is selected as the basic approach of IGBT physical model.This is mainly due to the fact that the lumped-charge modeling method does not use the high-level injection hypothesis,and presents the hole current and the electron current separately.It can also characterize the distribution characteristics of the base carrier under different operating conditions.It has the advantages of fast simulation speed,good convergence,clear physical meaning and fewer parameters required.Because of the traditional lumped-charge model has the problem of relatively low simulation accuracy,based on the modeling mathematical principle,this paper studies and analyses the model error from two aspects of model equation deduction logic and model simulation calculation logic.On this basis,the physical meaning of lumped charge in the model is redefined,and a new current transport equation and charge control equation are established.A new lumped charge modeling method with higher simulation accuracy is proposed,which is compared with the traditional lumped charge modeling method by simulation and experiment.Aiming at the field stop structure and the two-dimensional carrier distribution effect technology in drift region used in high power IGBT chips,a lumped-charge modeling method is proposed to establish a physical model that can characterize the electrical characteristics of high power IGBT chips.In order to optimize the operating characteristics of IGBTs under high voltage and high current conditions,manufacturers use different technologies to improve the IGBT chip structure.Considering the physical mechanism of semiconductor devices and taking 3.3kV/1500 A IGBT module as an example,this paper establishes the lumped-charge physical models of typical chip structures represented by ABB and Infineon respectively.Aiming at the different working characteristics of high-power IGBT modules under blocking voltage punch through(PT)and non-punch through(NPT)conditions,the physical model of field stop IGBT is applied to characterize the two operating characteristics respectively,and the simulation and experimental verification are carried out.Aiming at the problem of dynamic imbalance current in parallel application of IGBT,the lumped-charge model established in this paper is applied to establish an equivalent circuit model which can be used to analyze the imbalance current problem.It is an effective way to meet the current level requirements of the system to parallel IGBT,from cell to chip,and to the application of the power module.It is important to establish a circuit model that can analyze these problems because there are various problems in the IGBT parallel application.In this paper,the problem of dynamic imbalance current between parallel ports of IGBT power modules existing in a certain type of propulsion inverters is theoretical analyzed,and validated by the experiments.The equivalent circuit model of the IGBT module's working commutation circuit is established by extracting stray parameters.The theoretical and experimental validation is carried out by using IGBT lumped charge model and parallel combination simulation.The quantitative characterization of dynamic imbalance current condition of high power IGBT module's parallel power ports is realizedDue to the high-power IGBT working under the short-circuit and other extreme conditions will result in chip temperature changes extremely,based on the idea of electro-thermal co-simulation,a PSpice-Simulink electro-thermal co-simulation model using the IGBT lumped-charge model and RC thermal network model is proposed.The simulation study of high voltage and high power IGBT module and its parallel combination under short circuit condition is realized,and the experimental verification is carried out.For the application of the IGBT lumped-charge physical model,a systematic parameter extraction method is proposed.It is highly dependent on the extraction of model parameters to use IGBT physical models and realize high accuracy simulation.The extraction of parameters has always been a huge challenge for IGBT physical model widely used.In this paper,the IGBT physical model simulation parameters are firstly divided into two categories: one is the semiconductor physical constant,which could be obtained through semiconductor physics manual.The other type is internal parameters of the IGBT,including structural parameters and semiconductor physical parameters,which are extracted by a combination of reverse engineering and experiments.Finally,the parasitic parameters in the IGBT's working circuit are extracted.The main work of this paper is the modeling theory research of IGBT lumped-charge model,which lays a theoretical foundation for the high-power IGBT physical modeling work,and explores the application of the model used in IGBT parallel combination simulation,and promotes the application of IGBT physical model in guiding the design and problem analysis of power electronic systems.