| Bridge structures are commonly used for maglev due to the fact that the guide-way is all covered by the suspension frames of the maglev trains. Further, coupling vibrations could be caused between vehicles and the bridge. Vehicle system, levitation control system and the bridge form an interacting coupling system.Active levitation control can be taken as an input for vehicle and bridge systems, which will change the vibration status as well as the levitation gap. In other words, vehicle, guide-way and the control system form a self-excited vibration system. The levitation can be steady and quiet if the response of the system can rapidly convergent. While the external excitations are vibrating with a constant amplitude, the system can still achieve a steady but un-quiet levitation; the dynamic adjustment will generate certain vibration noise.when the response to external excitation cannot converge, but expand from small amplitudes to larger amplitudes, finally the suspension cannot remain stable, it appears to hit guideway, even lead to suspension crash.So maglev trains coupled vibration when running viaducts guideway is a key technical issue, involving multiple disciplines covering mechanical engineering, control engineering, civil engineering, etc, maglev applications have seen multiple maglev vehicle and guideway coupled vibration phenomenon at home and abroad. For example, Shanghai maglev TR08 largesing the quality and stiffness of the guideway to alleviate vehicle-track coupled vibration, but this not only increase the maglev line project cost, but also increases the difficulty of construction, has not conducive to the promotion of maglev transportation system.Therefore, comprehensive research of maglev trains vehicle-track coupled vibration, especially the interaction law among maglev vehicle-suspension control-guideway, three subsystems characteristics which maglev trains vehicle-track coupled vibration involved and conditions of the generation of coupled vibration,were studied. And then propose measures to ease the vehicle-track coupling vibration, is an inevitable requirement to reduce maglev transportation system construction costs, and promote maglev transportation technology to market, as line construction occupies more than 60% of maglev transportation construction total investment cost, therefore, in conditions of determining vehicle and control system, research the impact of the guideway characteristic to coupled vibration, reasonably determine the guideway basic requirements for the promotion of the system has great significance.Aiming at maglev trains vehicle-track coupled vibration problem in this thesis, based on specific vehicles and control system,carry out a theoretical analysis, numerical simulation and test study. Firstly, study the basic single electromagnet suspension unit from the principle, simulation analyze the impact of the gap feedback coefficient, velocity feedback coefficient, acceleration feedback coefficient to single electromagnet suspension systems, as well as the external interference at different frequencies and elastic supports to single electromagnet suspension system stability; then on the base of the suspension control strategy currently used in middle-low speed maglev, focus on outside interference consider the verticle magnetic-track relationship under minor fluctuations gap, and the impact of various parameters of vehicle in operating environment, such as body mass, running speed, the bridge features and irregularity excitation to magnetic-track relationship. For actual experimental device, based on the similarity theory, comparative analyze the characteristics similarity problem of a 1:2 ratio guideway and 1:1 prototype guideway. Vehicle-guideway interaction simulation results show that the proportion guideway of test rig simulated basically meet the needs of the vehicle-guideway coupled vibration experimental study, provides a theoretical basis for vehicle-guideway coupling vibration study in test rooms, provides reliable test conditions for predicting a new lines or to be built vehicle-guideway coupling.For vehicle-guideway coupling vibration study, EMD high-speed maglev train and middle-low speed maglev train are the same essentially.Finally, use the newly developed speed of 140 km/h middle-low speed maglev train single suspension frame physical, conducting vehicle-guideway coupling test by the use of test rig, Test study the stability of single suspension frame vehicle-guideway coupled vibration for different guideway quality, guideway elasticity, body mass and other conditions.The main conclusions studied in this paper are:(1) The analysis of single magnet suspension system shows for specific methods of suspension control used,low-frequency excitation has good following nature,ensures stable levitation gap,and has strong self-stabilizing ability for high-frequency excitation, yet with high vibration acceleration.Thus it is reasonable to apply this method to launch this simulated experiment and study of vehicle track coupling vibration.(2) The analysis of the influence of the feedback coefficients of suspension control methods used determined the reasonable range of values:the feedback coefficient of the gap of simulated vehicle track coupling vibration was 6000, the feedback coefficient of speed was 20, and the feedback coefficient of acceleration was 0.5.(3) The vertical track irregularity is the main excitation source of maglev train vibration. Vehicle vibration response increases along with the increase of the velocity; the influence of high-frequency track irregularity effect on vehicle is larger than that of low-frequency.(4) The stiffness of guideway support has a great effect on the deflection of the guideway support and the stiffness of guideway support should be not less than 6.5× 107N/m. Simply-supported beam and two-span continuous beam have little effect on maglev suspension stability, while two-span continuous beam is superior to simply-supported beam from the perspective of dynamic response.(5) A special train-rail coupling vibration test rig was developed to simulate the complex train-rail coupling vibration test in the laboratory and related experiment research was feasible. For particular suspension frame, the adaptability to different guideway characteristics can be studied and the basic features of guideway can be put forward accordingly, but the similarity of guideway properties under the laboratory and engineering practice need attentions.(6) Experiments show that the stable suspension capability of maglev is sensitive to the mass of the guideway, light guideway is very bad on the stable suspension capability of maglev; small stiffness of guideway support has negative influence on the stable suspension capability of maglev when the mass of guideway meets certain requirements; the heavier the vehicle load, the worse the stable suspension capability of maglev, therefore, reasonable mass and the equivalent stiffness of guideway support should be determined based on train maximum load. |
PDF Full Text Request