| This paper takes the permanent magnet electric levitation system as the research object.Through theoretical analysis and Ansoft Maxwell software simulation,the magnetic field distribution characteristics of the system are obtained,and the relationship between magnetic force-velocity-gap is obtained.The study on the suspension stability of the system found that the system has critical damping characteristics in the vertical direction,and this is the starting point of this paper.Compared with the technical characteristics of the existing permanent magnet electric suspension system damping scheme,the permanent magnet passive damping scheme studied in this paper is proposed,and then the damping scheme is optimized by theoretical calculation method and finite element technology.With reference to the finite element simulation results,simplified expressions of suspension force and damping force are obtained through curve fitting.And use Matlab/Simulink software to establish a dynamic model of a high-speed permanent magnet electric suspension frame with a damping module,and compare the dynamic response of the suspension frame with different damping schemes.The main conclusions obtained through the research of this article are as follows:1)The Halbach permanent magnet array effectively improves the buoyancy-to-weight ratio of the permanent magnet electric levitation system by virtue of its unilateral magnetic field enhancement feature.The external magnetic field of the Halbach permanent magnet array can be divided into horizontal and vertical components,which affect the levitation force and magnetic resistance,respectively.In the three-dimensional model of the array magnetic field,the horizontal magnetic field component is smaller than the vertical component,and the ratio of the two increases as the width of the magnet array increases;2)The levitation force and magnetic resistance of the permanent magnet electric levitation system increase rapidly with the increase of speed.As the operating speed continues to increase,the levitation force gradually tends to saturation,and the magnetic resistance quickly reaches the maximum value and then gradually decreases.The levitation force of the floating system has a regular exponential decay relationship with the increase of the levitation gap,and the buoyancy-to-weight ratio of the system is consistent with the change trend of the levitation force.Floating resistance ratio is positively correlated with speed and clearance,so the system is suitable for high-speed and large-clearance operation;3)The permanent magnet electric suspension system is vertically critically damped no matter in steady state or dynamic conditions,and external damping needs to be added to ensure the stability of the system.The damping scheme studied in this paper is mainly composed of permanent magnets and induction plates,and has the advantages of simple structure,large damping force,stability and reliability.According to research,the horizontal and vertical magnetic field components are close to saturation when the ratio of magnet width to length reaches 6.1 and 2.6 respectively;the thickness of the induction plate should be set to 25 mm.With reference to the optimization results,four damping schemes with different gaps were determined;4)When the system vibrates at low speed,there is a linear relationship between the damping force and the vibration speed.The permanent magnet passive damping scheme can effectively suppress the vibration of the system.The damping force is more sensitive to the working gap.The better working conditions of the damping scheme are low working gap and higher vibration speed.After research in this paper,the working gap of the damping module should be set at about 0.01 m.By reasonably setting the number of damping magnetic blocks and the working gap,the permanent magnet electric levitation system can adapt to more severe track conditions,so it can reduce the requirements of the track and reduce the cost of track construction. |
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