Reliability Analysis For High Voltage Electric System Of Pure Electric Bus Based On The Polymorphism Of Fuzzy Fault Tree

With the new energy technology matures, the number of pure electric bus in the public transportation is increasing rapidly. Pure electric bus has become one of the effective ways to improve public transportation. In the practical applications, the security problems of high voltage electrical system has aroused concern. To guarantee the safe operation of the high voltage electric system, reduce the failure rate of pure electric bus, reliability analysis of high voltage electric system becomes the key point.Reliability as the main standard to measure the quality of products,is gotten great attention in various engineering fields. For the high voltage electric system of pure electric bus, the reliability of single component plays a decisive role in the whole vehicle system. In thispaper, the high voltage electric system of pure electric bus was analyzed by the theory of polymorphic and fuzzy fault tree. First of all, according to the structure layout of pure electric bus, high voltage electrical components are divided into three main parts, including power battery system, high voltage wiring harness system, high voltage motor. According to the structure complexity of high voltage electric system and fault characteristics has the characteristics of fuzziness,the fuzzy set was introduced into the fault tree analysis. In order to express pure electric bus high voltage electrical system failure mode more reasonably,two state event and polymorphic events and polymorphic fault logic gate door unit were defined in the process of fault tree modeling. In the practical application, high voltage electrical system failure mode can be divided into two kinds of failure mode, which are function failure mode and deterioration model, corresponding respectively as two state events and polymorphic events.Secondly, the reliability of function failure mode was analyzed based on the fuzzy fault tree theory, the quantitative analysis modeling of state deteriorating pattern was built by the method of min-path set.which are used to solve the fuzzy reliability and the importance of fuzzy probability bottom events in function failure mode.Finally, based on the method mentioned in the previous section for electric bus high voltage electric system reliability analysis, a graphical user interface was designed by MATLAB GUI.Rely on the characteristics of its powerful function and high efficiency, the high voltage electrical system fault diagnosis knowledge base was developed, and combined the research results of previous chapters, the goal that human-computer interaction is achieved laser stripes.