IGBT Reliability Evaluation Of Pulse Power Supply For HIRFL

The magnet power supply of HIRFL-CSR is mostly switching power supply,which works in direct current or pulse current mode.There are a large number of IGBT devices of various power levels,and the reliability of IGBT is critical for the power supply reliability.With the increasing scale and higher requirements of accelerator,the research and prediction of IGBT reliability of accelerator pulse power supply is more and more urgent.The failure of power devices involves electrical,thermal,mechanical and other factors.When the accelerator pulse power supply operates in a special pulse mode,the IGBT module will produce low-frequency periodic power loss,then the junction temperature will fluctuate periodically.The materials of each layer of the chip will bear long-term thermal stress impact,resulting in device aging failure.Therefore,this paper studies the junction temperature prediction and reliability evaluation of IGBT devices for the pulsed power supply of Lanzhou heavy ion accelerator.Firstly,the loss model and foster thermal network model of IGBT module of pulse power supply are established,and the thermal electric coupling simulation is carried out,and the IGBT junction temperature fluctuation curve is obtained.Then,an experimental platform of IGBT junction temperature measurement based on infrared thermal imager is built.Taking 600 A / 1200 V Infineon IGBT as the research object,the fluctuation of junction temperature under three actual working conditions is tested.The results show that the error between simulation results and experimental results is within 3.5 ℃,which verifies the correctness of junction temperature analysis.Secondly,on the basis of junction temperature calculation,according to bayerr analytical life model and Miner linear cumulative damage theory,the cycle times of IGBT module under given conditions are calculated,and the expected life of IGBT module is evaluated.Finally,the power cycling aging test is designed,and the aging test platform is built to verify the life prediction results of IGBT module.In the aging test,test and record the saturation voltage drop of IGBT every 100000 power cycles until the saturation voltage drop rises by 5% and reaches the failure standard,and stop the test.The calculation results of reliability evaluation are 2.01 million cycles,and the test results of two IGBT modules are 2.55 million and 2.68 million respectively.In this paper,the junction temperature and life prediction of IGBT module of pulse power supply are studied,which is helpful to guide the thermal design of power supply,improve the reliability of power supply.