| High temperature superconducting(HTS)maglev based on flux pinning characteristics of YBa Cu O has remarkable advantages such as self-stable levitation,green environmental protection,and easy realization of cooling conditions.It has broad application value in civil and military technical fields such as maglev traffic,maglev bearing,electromagnetic ejection and so on.Around the development of rail transit technology,a number of test lines of HTS maglev have been built and used to carry out experimental research all over the world.In order to promote the engineering application,this thesis will study the vibration characteristics of HTS maglev based on Halbach permanent magnet guideway(PMG),and develop a high-speed maglev dynamic operation simulation test rig to support related dynamic experiments.The research contents and conclusions of this thesis are summarized as follows:(a)Aiming at the study of the interaction between high temperature superconductor and PMG,the scanning measurement experiments of levitation force and guidance force are carried out.And the vertical displacement of HTS bulks material relative to PMG and the variation law of levitation and guidance force at each measurement height are studied and analyzed.According to the research and analysis,a 2-D mathematical model of superconductor-PMG force is established.After identifying the parameters of this model by using the least square method,its simulation results are compared with the experimental results.It is found that these two results have a high degree of agreement.When the model is applied to the study of vehicle-PMG coupling dynamics,a damping term can be introduced to reflect the hysteresis effect,so as to establish a lateral-vertical coupling dynamic model which is convenient for fast calculation.(b)In this thesis,the vertical and lateral free vibration characteristics of the HTS maglev system under different field cooling height(FCH)are studied experimentally by using a scaled suspension frame with four dewars.According to the experimental results,it is found that under the condition of different FCH,the suspension system belongs to underdamped system and has obvious natural frequency.And,under the condition of the same FCH,the lateral natural frequency of the system is less than the vertical natural frequency.Moreover,the lateral natural frequency and vertical natural frequency of the system will decrease with the increase of FCH.Due to being cold to the midfield,the vertical free vibration of vehicle will hardly cause the lateral vibration,but the lateral vibration will cause the obvious vertical vibration.(c)By using the vibration apparatus,the vertical forced vibration experiments of the scaled suspension frame are carried out,and then the vertical forced vibration characteristics under different FCH are studied.According to the above experimental results,the system will resonate under the excitation of one-time natural frequency and two-times natural frequency.(d)In order to carry out the numerical simulation study on the vibration characteristics of the suspension system,a lateral-vertical coupling dynamic model is established by using the2-D force model and introducing a damping in the lateral and vertical direction to replace the hysteresis equivalently.Then,the simulation program is written by using MATLAB software.Initially,the simulation calculation of vertical free vibration and lateral free vibration is carried out based on the model.After comparing the experimental results with the simulation results,the high consistency between these results verifies the accuracy of this model.Then this model will be further applied to the simulation study of forced vibration.Through the vertical forced vibration simulation,it is found that the system will resonate under the excitation of one-time natural frequency and two-times natural frequency,which is consistent with the conclusion of the experiment.Finally,according to the simulation results of lateral forced vibration,it is found that the system has three resonance frequencies,which are one-time the lateral natural frequency,one-time the vertical natural frequency and the sum of lateral and vertical natural frequencies.(e)Aiming at the dynamic experimental study of HTS maglev,a dynamic simulation test rig for high-speed maglev operation is developed.Moreover,this thesis also introduces the structure and function,the technical parameters and vibration test system in detail.In this thesis,the 2-D superconductor-PMG force and vibration characteristics of the HTS maglev are studied by means of experimental measurement and simulation.The research conclusions have certain application value in the study of HTS maglev vehicle-PMG coupling dynamics.The high-speed maglev dynamic operation simulation test rig plays an important role in the research and development of HTS maglev. |
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