As the core power device of a modular multilevel converter (MMC), the failure mechanism study and condition monitoring technology of insulated gated bipolar transistor (IGBT) modules is of great significance in ensuring operational reliability. Distortion of operating parameters and internal structural abnormalities caused by IGBT module deterioration will seriously affect the working performance of an modular multilevel converter (MMC). At present, there are many reviews of IGBT modules status monitoring, but there is a lack of relevant summaries of IGBT module status monitoring in an MMC. First, the structural characteristics and working principle of an MMC are analyzed. Then, according to the failure mechanism of power-module and press-pack type IGBT, the state monitoring technology of the IGBT modules is summarized, and the state monitoring method of the IGBT modules in the MMC sub-module is supplemented and analyzed. Finally, in view of the shortcomings in current research, combined with the current research status, the research direction is suggested for IGBT module condition monitoring and evaluation in a flexible HVDC transmission system.

This work is supported by the Key Research and Development Program of Hunan Provincial Department of Science and Technology (No. 2021GK2020).