IGBT State Detection Based On Dynamic Thermistor Parameters

With the extensive application of power module IGBT in industry,new energy,power grid and rail transit,the reliability and security of IGBT has attracted widespread attention of people.Therefore,precise and real-time detection of IGBT's internal junction temperature is a premise of fast over-temperature protection and instantaneous criticality operation,and also an effective solution to improve system stability and reduce economic losses.The IGBT module that makes fast detection,low cost application and high-accuracy display come true has become a research hotspot in power electronics area in domestic and abroad.This thesis,based on dynamic and thermo-sensitive electrical parameters,carries out the research on state detection and assessment methods of IGBT.Details are as follows:(1)The IGBT module dynamic test platform is the basis for studying the dynamic characteristics of IGBT.Matlab/Simulink is used for system simulation on the test platform,so that the critical parameters that affect the performance of the platform can be found out.Finally,the design guideline of the testing system laying as a foundation for setting up IGBT module dynamic test platform prototype is concluded.(2)The IGBT module dynamic test platform prototype of 1000V/100A has been developed,whose design schemes are introduced from both software and hardware.The digital heating stage of this prototype is controlled artificially to make IGBT's internal junction temperature rise to the set value.This process simulates the fault state of the IGBT module.(3)When IGBT devices are turned on or off,the chip junction temperature will be simultaneously reflected in the physical and electrical parameters.The establishment of IGBT physical model helps to find the essential reasons that the IGBT turn-off delay time changes caused by physical junction temperature of IGBT.It is discovered by the experiment that the physical temperature of IGBT chips corresponds to the turn-off delay time.The change rule among collector-emitter VCE,electrode current Ic and chip conjunction temperature Tj is also found.Therefore,the research on the detection state and assessment methods of IGBT according to turn-off delay time is emphasized.(4)Parasitic inductance LeE exists in the IGBT module.Through experiment it is concluded that the physical junction temperature of IGBT chips is related to induction voltage FeE,on the basis of which the detection state and assessment methods of IGBT power modules are proposed.The measurement of thermo-sensitive electrical parameters indirectly contributes to detected temperature variations of IGBT chips,so as to realize the state assessment of IGBT.This method has good real-time performa-nce,high sensitivity and low cost,which opens up a new way for the state detection of IGBT power modules.