Lifetime prediction for press pack IGBT device by considering fretting wear failure

The reliability of the Press-Pack Insulated Gate Bipolar Transistor (PP-IGBT) device is important to guarantee the safety of modular multilevel converter (MMC). The fretting wear failure is the typical failure mode of long-time operation in the PP-IGBT device. However, the traditional fretting wear lifetime model of the PP-IGBT device only considers the fretting wear failure of the IGBT chip, which is difficult to accurately predict the reliability of the PP-IGBT device. The influence of fretting wear failure of all layers on the device's lifetime is ignored. This paper proposes a lifetime model of the PP-IGBT device by considering the fretting wear failure of all layers using the fault tree method. First, a finite element (FE) model of the PP-IGBT device is established by considering the multi-physics coupling, and the contact surface roughness change of each layer is obtained by power cycling simulation. Then, based on fretting wear failure and Basquin law, the lifetime of each layer is obtained, and a fault tree method is established to build the fretting wear lifetime model of the PP-IGBT device by considering the fretting wear failure of all layers. Finally, the power cycling experiment of the PP-IGBT device is established, and the experiment results are used to verify the effectiveness of the proposed lifetime model. The results show that the relative error between the proposed lifetime model and the experimental results is nearly 5 %.