The insulated-gate bipolar transistor (IGBT) module is a critical component of the traction converter in rail transit vehicles, and its reliability is essential for the safe operation of these vehicles. Junction temperature is a key parameter affecting the performance and reliability of IGBTs. Existing onboard traction converters lack effective methods for real-time monitoring of the IGBT module’s junction temperature. To address this issue, this article proposes a reduction thermal modeling approach based on Galerkin projection for real-time assessment of the junction temperature in IGBT modules. The high-order heat conduction equations can be projected into a subspace by only inputting the converter’s IGBT module’s convection coefficient and power loss and utilizing an eigenvalue decomposition method based on singular value decomposition (SVD) to extract basis vectors. This allows for generating a thermal field temperature map of the IGBT chip without additional external circuits or sensors, facilitating real-time and accurate evaluation of the IGBT module’s junction temperature. Finally, a power cycling experimental platform for the IGBT module was established, and comparative experiments under various operating conditions were conducted. The experimental results validate the real time and accuracy of the proposed method for assessing the junction temperature of IGBT modules.

The traction converter is the core component of an electric multiple unit (EMU), with the Insulated-Gate Bipolar Transistor (IGBT) serving as the key element that directly determines the operational status of the entire traction system. Predicting IGBT service life is therefore essential for fault prediction and health management in trains, providing critical support for ensuring operational safety, guiding condition-based maintenance decisions, and reducing life-cycle costs. In this study, we summarize the basic structure and failure mechanisms of IGBTs and propose a theoretical relationship between their performance parameters and degrees of aging, subsequently developing a method for predicting IGBT service life based on void ratio and service time. Additionally, a DC power cycle aging test is designed and carried out on the IGBT module according to the actual working conditions and the range of acceptable junction temperatures. The life prediction method proposed in this paper is used to analyze the test data, providing the predicted service life of the traction converter’s IGBT module. The results show that a new IGBT module can be used for 29.66 years or 17.8 million km, which can be used to support future maintenance work.