Research on Short Circuit Failure Mechanism of Press Pack IGBT Device Based on Al-Si Diffusion Molecular Dynamics Simulation

Abstract

AbstractPress pack insulated gate bipolar transistor (PP-IGBT) is widely used in HVDC converter valves for the advantages of high power density and short circuit failure mode (SCFM). In view of macroscopic measurement research on SCFM of PP-IGBT, which is difficult to reveal the failure mechanism caused by microscopic material failure, the SCFM mechanism of PP-IGBT based on Al-Si diffusion molecular dynamics (MD) simulation was proposed. Firstly, a MD model for the Al-Si diffusion of the IGBT chip was established, and the validity of the model was verified. Then, the law of Al-Si diffusion under different temperatures and stress were studied, and the occurred conditions of short circuit failure were got. Finally, a multi-physical coupling model of the PP-IGBT was established to study the transient thermal-mechanical distribution under short current. Based on the conditions of Al-Si diffusion, the mechanism and location of SCFM were analyzed. The results show that the Al-Si diffusion is more likely to occur at the boundary between the chip and the emitter molybdenum plate, which is the site of SCFM in the device.KeywordsPress pack IGBTShort circuit failureAl-Si diffusionMolecular dynamics simulation