Dynamic Characteristics Study Of Permanent Magnet Electrodynamic Suspension Vehicle Principle Model

With the rapid development of maglev technology,the emergence of permanent magnet structure represented by the Halbach array and the wide application of rare earth permanent magnet materials,the permanent magnet electrodynamic suspension(PMEDS)system is increasingly received by people.Compared with other maglev systems,the PMEDS system is simple in structure,inexpensive,and there is no need for complex cooling systems and control systems.This thesis applies maglev techniques to traditional automotive system,builds a new maglev vehicle principle model based on PMEDS principle,and study the working mode and dynamic characteristics of maglev vehicle principle model.Firstly,a 1:50 PMEDS vehicle principle model is built based on the ring Halbach structure.The core component are four radial permanent magnet wheels,which use annular Halbach structure to convert the inherent magnetic resistance in PMEDS system to driving force of maglev vehicle.By adjusting the rotational speed of magnetic wheels,adjustment of maglev vehicle principle model operations state and functions such as suspension,driving,braking and steering can be achieved.And the problem that the PMEDS system cannot statically suspend is also solved.Then its suspension and drive functions are verified through test.Secondly,the electromagnetic force math model of the PMEDS wheel is established.The levitation force and magnetic resistance of different suspension gaps and rotational speed of magnet wheel were studied by combining experiment with Maxwell finite element simulation,and the data of two methods are compared.The simulation result is used to fit the data to obtain the magnet wheel electromagnetic force model which is simple and easy to calculate for subsequent dynamic characteristics study.The suspension characteristics of the free vibration of PMEDS wheel are studied that verifies its underdamping characteristics and nonlinear feature.Then,based on the magnet wheel electromagnetic force model,the dynamics analysis software Adams is used to establish a dynamics model of PMEDS vehicle principle model using Simulink for system control and dynamic characteristics of PMEDS vehicle principle model under different working conditions is analyzed.The simulation calculation obtains the critical suspension speed,maximum suspension gap,working speed of magnet wheel and other performance parameters of PMEDS vehicle principle model.Three speed control schemes are proposed for PMEDS vehicle principle model and four-wheel drive is selected as the final solution.According to different driving conditions,the performance parameters are compared and analyzed to optimize the working mode of PMEDS vehicle principle model.Finally,two degree of freedom plane vibration model and road input model of PMEDS vehicle principle model are established to evaluate the driving performance.Referring to the evaluation method of traditional vehicle,the evaluation indexes are the vertical vibration acceleration of the vehicle body,the pitching angle vibration acceleration of the vehicle body and the dynamic travel of the wheel.The influence of different road grade,vehicle speed and relative rotational speed of magnet wheel on driving performance of maglev vehicle principle model are analyzed.The corresponding optimization measures for driving performance of PMEDS vehicle principle model are put forward.