Decoupling study on IGBT stress performance based on thermal-mechanical-electromagnetic multiphysics analysis

The press-pack Insulated Gate Bipolar Transistor (IGBT) is a critical power device in high-power electronic equipment and widely employed in flexible direct current (DC) transmission systems. Electrothermal stress fatigue are the leading cause of IGBT failures in engineering applications. However, previous studies mainly focused on the stress analysis from individual mechanical field in IGBT, thus the coupling effects of thermalmechanical-electromagnetic multiphysics fields on stress analysis are ignored, moreover, the thermal effect includes not only Joule heating but also electromagnetic losses, which lead to the interaction mechanisms on stress from various fields are currently unclear. In this paper, a novelty model of the IGBT considering mechanical field, thermal field, and electromagnetic field is proposed to comprehensively understand their inherent interaction mechanisms. Detailly, the paper explores the interaction mechanisms between fields by gradually coupling different fields. As a results, compared to the single mechanical field model, after thermal field is coupled into the mechanical field, the maximum stress steep rise to 26.2 MPa from 12.8 MPa. The electromagnetic field is further coupled into the mechanical-thermal fields, and the maximum temperature is increased by 6.2 %, which further leads to a 12.9 % increase in the maximum stress of mechanical field. The multiphysics coupling model has significantly narrowed the gap with the experimental results, the deviation in maximum stress has been reduced from 55.33 % in individual mechanical field to 2 % in Thermal-Mechanical-Electromagnetic multiphysics fields. The results indicate that the sequential coupling of thermal and electromagnetic fields significantly enhances the accuracy of stress analysis of IGBT.