| Power electronic system has the advantages of high energy conversion efficiency and good controllability.It has been widely used in aerospace,industrial automation,transportation,renewable energy power generation and other fields.However,due to the complex and severe working conditions,the reliability requirements of power electronic system are high.However,as the key unit of power electronic system,power devices play a decisive role in the safety and reliability of the system.Considering that IGBT module is the most widely used power device,this paper takes IGBT module as the research object,and mainly carries out relevant research work from the relationship between electromagnetic interference signal of buck converter composed of IGBT module and chip junction temperature and aging degree of bond wires inside the module.The specific research contents are as follows:(1)The common mode current and differential mode current paths of buck converter are analyzed,the mechanism of differential mode current generated by collector current change rate is pointed out,and the influence of chip junction and module bond wires aging on differential mode interference is analyzed in detail,which shows that it is more suitable for monitoring module status.Firstly,the working principle and characteristics of IGBT chip are analyzed,and the influence of temperature on the change rate of collector current during IGBT chip shutdown is studied.On this basis,the packaging structure of IGBT module is analyzed,and the influence of bond wires falling off on the differential mode interference path in buck converter is described.It is pointed out that junction temperature and bond wires lift-off are the two main factors causing the change of differential mode interference.(2)An aging monitoring method of IGBT module bond wires based on amplitude frequency characteristics of differential mode interference signal is proposed.Considering the influence of junction temperature change and bond wires aging on differential mode electromagnetic interference signal,an experimental test platform is built,and the full frequency band peak of differential mode interference signal in power circuit is measured under standard working conditions and actual working conditions respectively.A method to monitor the aging degree of bond wires in IGBT module based on the peak value of differential mode interference signal in low frequency band is obtained.(3)An on-line monitoring method of IGBT module bond wires aging based on phase frequency characteristics of differential mode interference signal is proposed.The current variation law in the switching process of IGBT chip is analyzed,the relationship between the aging degree of bond wires and the phase frequency characteristics of differential mode interference signal is studied,a phase angle characteristic measurement system of differential mode interference signal is established,and the on-line monitoring of the aging degree of bond wires in IGBT module based on the phase angle characteristics of differential mode interference signal is realized. |
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