Multitimescale Reliability Evaluation of DC-Link Capacitor Banks in Metro Traction Drive System

摘要

The reliability of DC-link capacitors in urban rail transit is considered as a major challenge because of significant maintenance impact. In this article, the DC-link capacitor reliability is researched in metro traction drive system. In the small timescale of control level, the current harmonics of multiple operating conditions and different control methods in the DC-link capacitor are discussed. The power loss is simulated by the capacitor harmonics of current and equivalent series resistance (ESR) in multioperating conditions. Considering electrothermal coupling, the time-ordered and continuity of thermal stress are analyzed to evaluate the hot spot temperature dynamic conformed to the reality. Combining with the analysis of electrical stress and thermal stress, a multitimescale capacitor reliability evaluation method is proposed. It is divided into four steps: the discrete small timescale, the single route timescale, the daily operation timescale, and the whole lifetime cycle. In the different timescales, the lifetime distribution changes with the dynamics of the complex mission profiles, so as to estimate the lifetime bottleneck of the DC-link capacitor banks with different control methods by the Weibull distribution. In addition, experimental validation is provided to verify the accuracy of the proposed method.