Lifetime Prediction Method of the Traction Converter IGBT Based on Plastic Strain Energy Density

Insulated gate bipolar transistor (IGBT) is the most important power electronic component in the traction converters of trains. During the operation of the IGBT, the solder layer is continuously subjected to alternating stress, which eventually leads to the fatigue failure of the solder layer. Therefore, an accurate assessment of the lifetime of the IGBT module solder layer is of great importance for the safe and reliable operation of the trains. First, the micromechanism of the plastic deformation of the base solder layer of the IGBT module is introduced, as well as the lifetime model based on the plastic strain energy density. Then, the total plastic strain energy density of the base solder layer is determined by conducting the accelerated aging tests on the IGBT module and combining the finite element simulation results. Meanwhile, the relationship between different aging degrees of the base solder layer of the IGBT module and the plastic strain energy density is studied by finite element simulation. Then, the lifetime of the base solder layer at different aging stages is calculated based on the above results, so that the total lifetime of the IGBT module is obtained. Finally, the predicted lifetime of the IGBT module by the proposed method is compared with the lifetime obtained by the accelerated aging test and compared with the traditional lifetime prediction method based on the Coffin–Manson–Arrhenius model. The comparison results verify the accuracy of the proposed lifetime prediction method in this article.

I. Introduction

High-power converter devices not only have obvious advantages in power conversion and power transmission but can also provide high quality and high efficiency power. Therefore, they are widely used in the fields of new energy, rail transportation, and aerospace [1]. The traction converter, as the most important power electronic device in the rail transit system, has shown that about 38% of the traction converter system failures come from the failure of power devices [2]. Among all power devices, the insulated gate bipolar transistor (IGBT) has 42% of the number used because of its characteristics of high current carrying and high switching frequency [3]. As the core device of the traction converter system, the reliability of the IGBT directly affects the reliability of the traction converter system and the rail transit train [4]. Therefore, the reliability study of the IGBT module has received a lot of attention. Lifetime prediction is an important way to improve the operational reliability of IGBT modules. Using the results of the lifetime prediction of the IGBT modules, system maintenance plans can be made on time. It is not only effectively reducing unplanned maintenance but also reduces the system downtime due to converter failure and increases the effective system operation time, which is essential for improving the system reliability.