## 1 Introduction
By introducing the magnetic vector potential, the analytical electromagnetic field of a conductive thin plate with the eddy current effect is derived. At present, most of the research on theoretical analysis simplifies the suspension system model to a two-dimensional model, and basically there is no research on a three-dimensional model. Numerical simulation can make up for this deficiency. Many scholars have observed the influence of the eddy current effect by establishing two-dimensional or three-dimensional simulation models. [PERSON] et al. [21] used the commercial software JMAG-Studio to carry out numerical analysis on the single suspension magnet model and calculated the distribution of the eddy current density and the magnetic flux density at speeds of 0 km/h, 108 km/h, and 216 km/h, respectively. The calculation results showed that the eddy current density increases with the increase of speed. [PERSON] et al. [22] established the single suspension magnet model, single module model, and multi suspension magnets model based on the HSST (High Speed Surface Transport) maglev train. The results once again showed that the eddy current density increased with the increase of speed, resulting in the decrease of the magnetic flux density and the suspension force. [PERSON] [15] established the single suspension magnet model and single module model based on the CMS maglev train and conducted a three-dimensional transient magnetic field simulation with the help of finite element simulation software Ansoft. Then, the numerical solution of the eddy current effect is obtained and compared with the analytical solution. [PERSON] et al. [23] used Maxwell software to establish the models of one suspension module and two suspension modules, respectively, and analyzed the changes in eddy current density, the magnetic flux density, and the suspension force at different speeds. [PERSON] et al. [24] used Maxwell software to establish a finite element model. The numerical simulation results showed that in the process of high-speed running, the distribution of the magnetic flux density changed significantly, which seriously affected the suspension electromagnetic force. During the experiment, the influence of the eddy current effect can be judged by observing the suspension current data. Because the eddy current attenuates the suspension force, the suspension system will increase the suspension current to ensure the required suspension force. [PERSON] [15] conducted experiments of the maglev train with three car riages on the Tangshan maglev experimental line. The results showed that the eddy current does reduce the suspension force, which is consistent with the theoretical analysis. [PERSON] et al. (2018) listed the experimental data of the suspension current at the speeds of 0 km/h, 60 km/h, and 90 km/h. The results showed that the higher the speed, the greater the suspension current. [PERSON] et al. (2018) gave the suspension current data of the Changsha maglev line. The results showed that with the increase of the speed, the suspension current of the front magnet increased to 1.54 times that of the stationary state and 1.37 times that of other suspension magnets. On the whole, experimental data on the influence of the eddy current effect on the suspension system in publications are few. In addition, only a few current values are given in the existing experimental results. In this article, the experimental data of the maglev train with six carriages will be analyzed. Unlike existing research, these experimental data are the continuous current values. Scholars generally believe that the influence of the eddy current effect on suspension force cannot be ignored, especially when the train runs at a high speed. In order to suppress the influence of the eddy current effect, scholars have put forward different kinds of solutions. From the perspective of the suspension control algorithm, [PERSON] et al. (2018) used an effective PD controller to control the established suspension system model. [PERSON] et al.