Reliability Modeling And Life Evaluation Of Traction Drive System For Metro Vehicles

Urban rail transit vehicles,especially subway vehicles,are important railway equipment on the road of urbanization in China.Metro vehicles have played a crucial role in shortening people's travel time in China's urban construction and have greatly accelerated the city's blood flow.At the same time,problems such as interruption of driving caused by power system failures need to be solved.The traction drive system is the source of power for the subway vehicles.Once a failure occurs,the train stops operating.As a result of the entire line operation,traffic scheduling will have a negative impact.Therefore,ensuring the operational reliability of the traction drive system is an important part of the train maintenance work.The existing research mainly focuses on single components or single systems,and there are few complete research methods from unit to system.In addition,the existing methods for the reliability study of metro vehicles are mostly borrowed from other industrial systems and are not targeted;Reliability analysis methods such as analyzing component failure modes are rare.This article will start from the unit level components,first analyze the failure modes of the key components of the system,collect the prior information such as its failure form,assume the life distribution law of the components according to the obtained prior information,and use the multi-layer Bayes method to the traction drive.Critical components of the system are used for reliability modeling and life assessment.From the unit components to the system,the GO method is used to model the reliability of subsystems in the system.From the bottom up,the GO method model is established from the subsystem to the large system using the same method to calculate the reliability index of the traction drive system.Finally,Monte-Carlo numerical simulation method is used to verify the method provided in this paper.The main contents are:(1)Reliability evaluation of high-speed circuit breakers,key components in traction drives.According to the collected high-speed breaker failure modes,assume that the lifetime distribution of the high-speed circuit breaker obeys the two-parameter Weibull distribution,the posterior distribution of the high-speed circuit breaker is calculated using the multi-layer Bayesian method,that is,the cumulative failure probability,and finally the least square method is used.The parameters are estimated to obtain the reliability index of the high-speed circuit breaker.(2)Reliability assessment of another critical component inverter in the system.Considering that the failure mechanism of the inverter is mainly caused by the failure of the IGBT module,the regression model in Bayes is used for analysis,and a certain type of inverter is subjected to sequential stress acceleration degradation test.With the voltage as the acceleration stress,a linear growth stress level with a proportional coefficient of 0.8 is set,and the loss of the inverter is determined by detecting the collector emitter voltage of the IGBT and the forward voltage of the diode in the inverter.The experimental data is analyzed to obtain its acceleration model,and the model parameters are estimated using the least squares method.At the same time,the Bayesian reliability evaluation of the inverter is performed to obtain a reliability curve.Finally,use the acceleration model obtained before to solve the reliability under the normal stress level.(3)Investigate the structural composition and failure modes in the traction drive system.The traction drive system is divided into six parts: the pantograph subsystem,the high-voltage loop subsystem,the inverter subsystem,the cooling subsystem,the control subsystem,and the motor.The GO method is used to model the large-scale system from bottom to top,from unit components to subsystems,and from subsystems to large systems.Using the reliability indices of the unit components calculated in the previous article and the reliability parameters of the relevant components in the relevant national standards,the reliability indices of the system are calculated to complete the system life assessment.(4)In order to verify the effectiveness of this method,the reliability of the entire traction drive system was simulated.A detailed description of the definition model and the generation of random numbers is given.Detailed steps of the simulation are listed.According to the procedure programming,the simulation is implemented in MATLAB.The final output simulation results are compared with the results obtained by using the method of this paper.The relative error is Within the allowable range,verify the effectiveness of this method.This paper fills the blank of the reliability modeling and life assessment of the traction drive system for urban rail transit vehicles,it provides a method for the reliability evaluation of traction drive systems;it points out the weak links of the traction inverter in the key components of the system.Provide reference;provide the life indicator of the traction drive system,make the system perform predictive maintenance before failure,reduce the failure rate,and achieve reliability-centered maintenance.