MMC子模块关键器件长时间尺度运行工况老化分析与可靠性评估

In the reliability study of modular multilevel converter (MMC), the research of key devices mainly focuses on the degradation of physical performance, but its results are not well used in the system level reliability evaluation. In order to correlate operating conditions with device aging and reliability, a reliability evaluation method of device aging based on MMC task profile is proposed. Firstly, the power loss of MMC key devices is deduced. Combined with the mission profile, the rainflow counting algorithm is used in the junction temperature calculation. According to the linear fatigue cumulative damage principle, the damage and lifetime of the devices under the electric heating coupling condition are obtained. According to the aging problem of the device, the aging phenomenon of the device is more obvious than that of the varying working stress under constant high stress by analyzing the aging increment under different working conditions. The reliability analysis method based on exponential distribution is improved, which provides a reference for the replacement of module components in regular maintenance.