Plug And Play Monitoring System Of Bonding Wire Faults In IGBT Power Modules Based On Voltage Parameters

Nowadays,IGBT power modules are widely used in photovoltaic power generation,wind power generation,smart grid and electric vehicles and other emerging industries,and meanwhile the reliability of power modules is also increasingly concerned by the industry.Long-term thermal-mechanical cumulative fatigue damage can easily lead to permanent failure of high-power IGBT modules.The main failure modes are bonding wire fatigue and solder layer damage,especially the former.Starting from the internal physical structures of IGBT power modules,this paper essentially analyses the reasons for the failure of IGBT power modules and proves that the difference of thermal expansion coefficient of various physical materials is the key factor leading to the failure of bonding wire in IGBT modules.Secondly,the monitoring principles of monitoring methods based on saturate voltage drop and diode terminal voltage are analyzed in detail,and the on-line monitoring mechanism of three-level NPC modules is introduced.This method establishes the relationship curve between IGBT saturate voltage drop and junction temperature,and the relationship curve between diode terminal voltage and junction temperature,and judges the healthy state of bonding wires in power modules according to whether the curves move up or not,so as to achieve a more comprehensive monitoring of bonding wires in IGBT modules.Based on monitoring methods of IGBT saturated voltage drop and diode terminal voltage,combined with LabVIEW,a plug-and-play monitoring system for bonding wire faults in IGBT modules is designed in this paper.The system is divided into three parts:control module,monitoring module and modulation modification module.There are plug-and-play interfaces between each part,which can be used for on-line and off-line monitoring of various types of IGBT modules.All monitoring instructions are sent by the control module at one time.The operation is simple and the application is flexible.In order to verify the rationality and feasibility of the monitoring system designed,the IGBT modules in 15 KW three-level NPC photovoltaic inverters is monitored online and offline by the designed monitoring system,and the ideal experimental results are obtained.In addition,the monitoring system designed in this paper can measure a variety of electrical parameters of IGBT modules,including junction temperature,shell temperature,monitoring current,IGBT saturation voltage drop and other parametersneeded for solder layer damage monitoring.Therefore,the monitoring system is expected to be used for monitoring of solder layer damage in IGBT modules.