High-Speed Train Traction Drive System Dynamics Modeling And Gearbox Vibration Characteristics Analysis

As one of key systems of high-speed trains,the operational reliability of the traction drive system has been the focus of research in the field of high-speed train technology.In this thesis,a fine dynamics model of high-speed train with traction drive system was established.Considering the internal and external excitation sources of the traction drive system,structural vibration fatigue theory was used to calculate the fatigue load of flexible structure under various excitations.Kernel density estimation(KDE)method was applied to extrapolate the structural fatigue load,the dynamic characteristics under internal and external excitation and the influence of traction motor output torque pulsation on the gearbox housing were studied.The vibration response and fatigue damage of the high-speed train's traction drive system were calculated and analyzed.The present work can provide important ideas for designing and solving harmonic vibration problems in the high-speed train's traction drive system.The specific research work carried out is as follows.(1)A modal test of the gearbox housing of a high-speed train was conducted to identify the modal parameters of the gearbox housing when the vehicle running on line.The finite element model of the corresponding gearbox housing was established and finite element model updating of the gearbox body was performed using the Crow Search Algorithm with Levy Flight(LFCSA)based on the modal test data.On this basis,the ANSYS and SIMPACK software were used to build a fine model of the rigid-flexible coupling dynamics of high-speed train traction drive systems.A traction drive control submodel(Field-Oriented Control,FOC)was built using the MATLAB/Simulink toolkit.In order to study the influence of harmonic pulsation of the DC link on the traction drive system,a software filtering compensation module was also introduced into the submodel.Based on the above models,a fine rigid-flexibleelectromechanical coupled dynamic model of the traction drive system of high-speed trains was established,which can provide a simulation platform for the study of the mechanical and electromagnetic coupled vibration characteristics of traction drive systems of high-speed trains.(2)The gearbox housing vibration response under different wheel polygonal wear conditions was simulated and analyzed.Based on the wheel polygonization evolution data obtained from the long-term tracking test of high-speed train service performance,the dynamic stress of the gearbox housing at different wheel polygonization evolution levels over 0-14 million km of operation was calculated.The sample data was extrapolated using the KDE method to evaluate the impact of wheel polygonal wear on gearbox fatigue damage.The simulation results show that the dynamic stress of the gearbox housing under the wheelset elastic deformation condition are consistent with the measured data,indicating that the establishment of wheelset and gearbox flexibility models is necessary to accurately assess the fatigue strength of the gearbox housing under the wheel polygon wear condition.(3)The harmonic condition of the motor torque caused by the characteristics of the traction inverter was analyzed under the ideal operating condition of the DC link without harmonic pulsation.The vibration response and fatigue damage of the gearbox housing during the uniform operation of high-speed trains under the powered condition were studied,and the influence of the torque pulsation on the structure of the traction drive system was analyzed.The results show that the traction torque has an amplifying effect on the vibration acceleration and dynamic stress of the gearbox housing.(4)The failure of the LC filter in the DC link or the absence of LC filtering in the ACDC-AC circuit can lead to DC voltage pulsation and cause the motor traction torque pulsation harmonics and the vibration response of the traction drive system related structures.The results show that harmonic pulsation of the DC link causes localized abnormal vibration of the bogie,significant increase in the dynamic stress and accelerated the structural fatigue damage.The vibration effects of harmonic excitation on the mechanical structure can be suppressed by integrating a software filter compensation module in the traction control submodel to eliminate harmonic pulsations of the Q-axis current in DQ synchronous rotation coordinate system to suppress abnormal harmonic signals in the output torque of the traction motor.The effectiveness of the method was verified by comparing the simulation results with the measured data.The results show that the software filter compensation module can effectively eliminate the abnormal vibration of the local structure of the bogie.