Loss Analysis and Junction Temperature Prediction for Modular Multilevel Converters

With the increasing efficiency and reliability requirements of power systems, optimizing the performance and reliability analysis of modular multilevel converters (MMCs) has become crucial. And the insulated gate bipolar transistor (IGBT), as the core component of the MMC converter, the accurate assessment of its power loss is crucial for the operation of the MMC converter. In this paper, we firstly describe the topology and operating characteristics of the half-bridge MMC, and analyze the operation of the sub-modules, in order to propose a fast electro-thermal joint calculation method based on junction temperature feedback. The method firstly simplifies the sub-module model and calculates the individual sub-module power loss, secondly establishes the thermal network model of the IGBT device in the half-bridge sub-module, and unites the loss calculated from the output of the electrical simulation with the junction temperature predicted by the thermal network model, and finally verifies the correctness of the electro-thermal coupling model proposed in the paper in Matlab.