Research On Eddy Current Effect Of Electromagnet And Levitation Force Compension Method Of Medium-Low Speed Maglev Train

China’s magnetic levitation technology has made rich achievements since the 1980 s,low and medium speed maglev train is developing rapidly in recent years because of its unique advantages in urban transportation.At present,the technology of low and medium speed magnetic levitation has been relatively mature,but due to the great market demand,the application of the technology is still the process of research.In this paper,the static and dynamic electromagnetic properties of electromagnets and the influence of eddy current effect on them are analyzed by combining theoretical analysis and simulation.Since the electromagnet levitation force decreases as the speed increases in real situation,it is necessary to seek compensation methods to meet the demand of train speed increase.Three methods of levitation force compensation are analyzed and compared in this paper.Firstly,the basic theory of electromagnetic field and the analysis method are introduced,the electromagnetic force of electromagnet at rest is obtained by analytical method,the transient electromagnetic force of electromagnet considering the effect of eddy current of steel rail and its characteristics are calculated,and the relationship between air gap magnetic density and levitation force with speed is analyzed.Next,the magnetic field distribution,levitation force and air gap magnetic density of a single electromagnet and an electromagnet module with multiple electromagnets are calculated by using Maxwell finite element simulation software.The influence of eddy current effect on the electromagnet and the relationship between levitation force and speed are also analyzed.Finally,three methods are studied and analyzed to compensate for the electromagnet levitation force.The first method is to increase the length of the electromagnet at the head of the module,the second method is to add a compensating electromagnet in series with the two main electromagnets at the head of the train,and the third method is to change the track to a multi-layer laminated structure.The results are verified by theoretical calculation and simulation and analysis,shows that all three methods can make the electromagnet levitation force meet the demand of stable operation of the train at the speed of 200km/h.At the same time,three methods are compared,and their advantages and disadvantages in practical application are analyzed.