RAM Analysis And Research Of CRH380B Emus Traction Motor Unit

The traction motor unit is composed of traction motor,motor cooling system and sensor,which is an important part of the EMUs and provides power for the operation of the EMUs.Reliability,availability and maintainability analysis for traction motor unit is important to improve the safety of traction motor unit and railroad operations.The complex structure and the diversity of faults in the traction motor unit of a EMUs lead to unclear failure mechanisms,making it difficult to model the motor set for reliability analysis.System availability is often evaluated using state transfer probabilities.Calculating state transfer probabilities based only on the frequency of failures and the time between failures leads to a correlation between the availability of each failure category and the failure rate,resulting in errors in the requested availability results.In addition,the existing mechanical system maintainability analysis method cannot be directly applied to the traction motor unit,and the analysis indexes must be determined by combining the usage characteristics of the EMUs and traction motor unit,and designing the calculation method of quantitative analysis indexes.In response to the above issues,the following work has been carried out in this article:(1)In view of the difficulty in reliability modeling of EMUs traction motor unit,the relationship between different fault categories is determined by analyzing the failure mode and effects analysis of the failure unit of traction motor unit,and a fault tree analysis model is established in combination with the fault mechanism analysis of CRH380 B EMUs traction motor unit,which establishes the model basis for the reliability and availability analysis of traction motor unit,and converts the fault tree analysis model of traction motor unit into Bayesian network,The posterior probability of each fault of motor unit is calculated through Bayesian network.According to the reliability ranking of each fault event based on posterior probability,the results show that contactor fault,cooling fan fault and air switch fault are the three fault categories that are most likely to cause power unit fault.(2)In commonly used availability calculation methods,the probability of system state transition is only calculated based on the frequency of faults and the time between faults,which leads to a correlation between the availability of various fault categories and the failure rate.The maximum likelihood function is introduced to deduce the failure state transition probability of each fault category,and the Markov process method is used to calculate the system availability.This method was used to solve the availability of EMUs traction motor unit at different times and operating routes,and qualitative analysis was conducted on them.The availability analysis shows that the motor noumenon unit is a unit with low availability for the electric unit,and the availability of different faulty units in different operating lines will also show differences.(3)To prevent EMUs safety accidents caused by faults in the traction motor unit,and to accurately and efficiently formulate maintenance plans and equipment replacement cycles,it is necessary to analyze the maintainability of the system.According to the standard document of the RAM application guide for railway products,the maintainability analysis indicators of the EMUs traction motor unit have been determined.According to the fault characteristics of traction motor units in the middle life of CRH380 B EMUs,the quantitative calculation method of average maintenance time with uniform distribution,normal distribution,logarithmic normal distribution distribution and mixed distribution is deduced.Based on availability indicators,numerical simulations were conducted using MATLAB to simulate the failure repair time samples following different distribution types.The above method was used to calculate the average repair time of the samples.