## 4 Improvement Scheme  
In order to suppress the influence of the eddy current effect on the suspension system, the improvement scheme from the perspective of the rail structure is put forward in this section, which includes three rail structures: type I, type II, and type III. Figures 11-13 show their cross-sections, which are improvement models based on the reference [15]. Call the model in reference [15] the original simulation model. The consistency between the original simulation model, the theoretical model, and the physical model has been explained in reference [15] and will not be repeated in this article. This section focuses on the effect of the improvement models. In Figures 11-13, \(x_{2}\) = 9.3 mm, \(y_{2}\) = 0.19 mm, \(x_{3}\) = 5.6 mm and \(y_{3}\) = 0.11 mm. So that the duty ratio of the improvement models is the same. When using the simulation software ANSYS MAXWELL for the electromagnetic field analysis, the operation steps are as follows. Figure 10: Variation of the suspension force with the rail width. Figure 9: Influence of eddy current on suspension force. Step 1: Build the model. In this article, the simulation model is established in the three-dimensional transient field and its three-dimensional structure is shown in Figure 14. Set the single suspension magnet to move forward at the speed \(v\) along the positive direction of the Y axis. At present, the EMS medium-and-low-speed maglev train can achieve a maximum speed of 160 km/h. The research of this article is devoted to improving the train speed, so a higher and reasonable speed of \(v\) = 300 km/h is set. Step 2: Define material properties. The coil material is aluminum. The material of the rail and the suspension magnet is Q235, whose magnetic flux density reaches saturation at about 1.4 T, conductivity is \(5\times 10^{6}\) S/m, and density is 7850 kg/m\({}^{3}\). Step 3: Set boundary conditions. Use the create-region operation to draw the solution domain in the outermost part of the whole model. Where the padding type is percentage offset and the padding data are set as 500 in the X and Z directions and 100 in the Y direction. The boundary condition is set as zero tangential H field. Step 4: Set excitation. The number of turns is 360 and the current is 35 A. Step 5: Set solution parameters. Assign the suspension force of the rail. Step 6: Set the mesh. The method of manual division is used to limit the maximum size of the mesh. The mesh generation effect is shown in Figure 15.  
Step 7: Set the solver. The simulation step in the solver is 0.0001 s and the simulation time is 0.06 s when the speed \(v\) = 300 km/h. Figure 11: Cross section of type-I rail. Figure 13: Cross section of type-III rail. Figure 12: Cross section of type-II rail. When the suspension magnet moves forward along the positive direction of Y axis at speed \(v\), the amplitude of the suspension force will change from large to small and gradually stabilize under the influence of the eddy current effect. There is no induced eddy current in the rail at the initial time, and the suspension force is the maximum at this time. In the simulation results, it is about 7 kN. When the amplitude of the suspension force is stabilized, the suspension forces of type I, type II, and type III rail are 5.80 kN, 6.59 kN, and 6.89 kN, respectively. This shows that at the same speed, decreasing the laminated width can increase the suspension force. In order to observe the variation of the magnetic field quantitatively, reference plane 1 is set. The size of reference plane 1 is the same as the XY plane section of the rail. Moroever, the position of reference plane 1 is shown in Figure 16. Since the suspension force is mainly generated by the component of the magnetic field along the Z axis, the component of the magnetic flux density along the Z axis \(B_{z}\) is observed. After integrating \(B_{z}\) along reference plane 1, the magnetic flux \(\Phi\) can be obtained. Figure 17 shows the magnetic flux \(\Phi\) changes with time.