Study On The Paralleling Characteristics Of High-power IGBT Modules

Insulated Gate Bipolar Transistor,which conbines the Advantages of MOSFET and BJT,possesses the merits of strong current ability,fast switching speed and small driving power,and has been widely used in Electric energy saving,new energy power generation,electric traction,smart grid and military equipments.However,the power handling capability of the single device can not meet the large capacity power electronic device of the increasing demand of electric power handling capacity and the specific package does not exist,so,based on the foundation of improving the power handling capacity of a single device.Device combination technology,in which parallel is the main content,are main development direction for a long time.Taking the reliability,availability and application into consideration,combination technology is an important future technical direction of the large capacity power electronic technology and application.Furthermore,the parallel of IGBT modules can not only increase the output current of the converter,but also increase the power density of the converter.And that baancing temperqture distribution of paralleled IGBT modules,optimizing the internal layout of the converter and improving the cost performance of the device.However,the current of paralleled IGBT modeles are usually imbalanced,during to the discreteness of devices parameters,unreasonal design of driving and power circuit and temperature inconsistencies,so,the output current of the converter must be derrated.However,the derating factor cann't be accurately quantified,but,based on the he worst condition of design and operation assumption.This assumption is obviously inconsistent with the real time operation of the converter.Generally,in order to ensure the long-term reliability of products,engineers usually overestimate the IGBT derating coefficient,and the direct influence of such behavior is to increase the design cost and the cost of using products.Meanwhile,the imbalance of current cause overload of someone module,which not only increases the possibility of device damage,but also reduce the reliability of a real system.Therefore,to analyse the reasons of current imbalance,how to balance the current among the paralleled IGBT modules and to investigate distribution of temperature field are very significant.Firstly,the structure composition and characteristic principle of IGBT are analysed.Secondly,for the reason of static and dyramic current imbalance,detailed theoretical analysis,simulation and experimental verification are carried out,from two aspects of static current imbalance and dynamic current imbalance.Then,aiming at the causes of static and dynamic current imbalance,based on the existing derating method and series plus impedance method,the method of coupled inductor current sharing and active gate control are proposed,and theoretical deduction and experimental verification are carried out,showing the availability of the proposed methods.Finally,the three-dimensional finite element simulation model of electric IGBT module is constructed in the ANSYS Icepak software.Based on the analysis of electrothermal characteristics of single IGBT module,the electrothermal simulation model of paralleled IGBT modules is constructed.Also the simulation results from the analysis of characteristics of paralleled applications,provide a feasible reference for improving the reliability of modules and systems in engineering application.