Research on Self-Heating Multi-Pulse Test Method of MMC Power Sub-module

The modular multilevel converter (MMC) in flexible HVDC transmission systems consists of a large number of power modules, and the reliability of IGBT devices in the power modules is crucial for the long-term stable operation of the system. Aiming at the half-bridge MMC power module, a self-heating multi-pulse test method for IGBT is proposed. This method can self-heat the tested IGBT and carry out multi-pulse test without disassembling the power module. In this way, dynamic parameters of IGBT can be extracted to provide a basis for analyzing the aging degree of IGBT in MMC power module. The feasibility of this test method is verified by theoretical calculation, simulation analysis and experimental verification, which will provide a new idea for the regular maintenance of modular multilevel converter system.