The cross-connection cables (CCCs) of null-flux coils (NFCs) are used to improve the guiding stiffness of superconducting electrodynamic suspension (EDS) system. In practical applications, it is very important to check the connection state of the CCCs. In this article, a detection method of CCC open-circuit fault of NFCs for superconducting EDS train was proposed. First, based on the dynamic circuit theory, the working principle of the detection method was explained. Then, the detection system was designed by combining the electromagnetic design and hardware design. The designed detection system consists of four parts, that is, a transmitting coil (TC), a receiving coil (RC), a high-frequency excitation module, and a signal processing module. The effectiveness of the detection method was validated via low-speed off-line and on-line tests. The feasibility of applying this detection method to high-speed (1000 km/h) and dynamic situations was validated by simulation analysis. The results of this article could provide useful information for the fault detection of ground coils for superconducting EDS train.

In this article, we propose a novel analytical-experiment coupling method to characterize the electromagnetic forces of superconducting electrodynamic suspension system. The basic idea of this method is that, the induced currents of the ground null-flux coils (NFCs) are predicted by analytical calculation, but the electromagnetic forces on the onboard superconducting magnets are directly measured. To ensure the calculation accuracy of induced current, a Neumann's formula-based analytical model was derived and its accuracy was confirmed by comparing with the finite-element model and the existing analytical model, which is based on the harmonic approximation. The prominent merit of this method is that it is free of high speed rotating motion and thus, has no limitations of testing speed. We further made a proof-of-principle experimental setup, which consists of a coated-superconductor magnet and a few NFCs, to check the effectiveness of the proposed method. By this setup, the dependence of electromagnetic forces, i.e., levitation force, guidance force, and drag force, were measured as a function of displacement and speed. It was found that, results obtained by the proposed method are in agreement with 3-D finite-element simulation, which to some extent validatesthe proposed method.

The superconducting electrodynamic suspension (EDS) train, which has reached a manned speed of 603 km/h in 2015, and is therefore regarded as one of the most attractive technologies for the higher speed train. In the superconducting EDS train, the discrete layout of ground null-flux coils causes the additional electromagnetic ripples towards the bogies, making the vibration control more essential to ensure the running performance. In this work, a fourteen-degree-of-freedom dynamics model of superconducting EDS train, was established to explore the effective strategy for vibration reduction. This model uses the time domain wave of track irregularity spectrum as the input of vehicle system. MATLAB/Simulink and "Zhai’s method" are both adopted to solve the vehicle dynamic model and validate the model. Using these models, the effectiveness of the proportional force and maximum force for the primary suspension was examined. The results show that the maximum force strategy has advantage over the proportional force strategy in terms of energy consumption and vibration sensitiveness. However, the electromagnetic damping control can only suppress the vibration of bogie. To achieve an overall vibration control, the "ON-OFF" sky-hook damping was further introduced to the secondary suspension to suppress the vibration of car body. We find that, the control effect is preferable with the damping value being between 5 kN·s/m and 10 kN·s/m. Therefore, the cooperative control, considering both the primary and secondary suspensions, is necessary to meet the Urban Tracked Aircushion Vehicle Standard and provide theoretical supports for the suspension design of superconducting EDS train.

The mutual inductance is the core parameter of electrodynamic suspension (EDS) as it couples the onboard coils and ground coils to realize the stable suspension. The precise and efficient calculation of mutual inductance is therefore of great significance to understand and optimize the characteristics of EDS train, which has achieved a manned speed in excess of 600 km/h. In this article, we proposed a calculation method of mutual inductance, considering the geometrical details of coils and the attitude of bogie, by means of the 3-D discretization of coils and the spatial coordinate transformation of discrete units. Based on this methodology, the analytical model was established, and the dependence of computation time and precision on the discretization degree is intensively discussed. Afterward, the finite-element analysis (FEA) was adopted to check the accuracy and effectiveness of the proposed methodology. Compared with FEA, the computation time has been reduced by 97% with accuracy reserved. Finally, a testing platform was constructed to further verify the availability of the proposed model. In summary, the proposed methodology can realize efficient calculation of mutual inductance in consideration of more realistic situations, providing an invaluable tool for the complex studies of superconducting EDS train.

该文提出一种等效模拟零磁通式电动悬浮的系统,阐述系统的工作原理和结构组成,并结合有限元仿真与实验测试对系统的电磁力特性进行分析.建立系统的三维有限元模型,研究了线圈运动速度、磁体垂向与横向偏移、线圈极距对系统性能的影响规律.研制样机并进行实验测试,测试了不同工况下悬浮力的变化情况,并与仿真结果进行对比分析,证明了有限元模型的准确性与可靠性.另外,实验样机实现了磁体的起浮,为零磁通式电动悬浮在轨道交通的应用与设计提供了理论依据.

研究了一种直线感应式的轨道涡流制动器,该制动器不同于传统的直流励磁涡流制动器和永磁涡流制动器,而是以三相交流励磁来产生气隙磁场;相较直流励磁和永磁涡流制动器来说,其有着制动力平稳,低速仍有较高制动力的优点.本文详细介绍了直线感应式轨道涡流制动器的基本原理以及基本结构,并通过有限元法对影响该制动器制动性能的电磁参数以及机械参数,比如运行速度、气隙大小、励磁电流、励磁频率等进行了相应的仿真计算,为轨道涡流制动器的研究提供了参考价值.

High-temperature superconducting (HTS) magnetic levitation (maglev) bearing is regarded as a promising candidate for the future high-speed transportation system as a result due to the merits of passive stabilization, low power consumption and environmental-friendliness. The dynamic characteristics are critical for its high-speed applications performance. The current research on the dynamic characteristics of linear HTS maglev bearings is limited to small-scale, approximate harmonic excitation or low-speed. In this paper, the expression of random guideway irregularity spectrum in time domain, which could describe the realistic guideway excitation in rail transportation system, was obtained by Inverse Fourier Transform method with a homemade code. Based on a strong-coupled electromagnetic-thermal-mechanical model, the dynamic characteristic of a heavy-load linear HTS maglev bearing under the excitation of random guideway irregularity with different speeds (400, 500, 600 km/h) and guideway irregularity amplitudes were studied. The results show that the influence of high speed and the temperature on the dynamic stability of linear HTS maglev bearing is quite limited, which is contrary to common concern. On the other hand, the guideway irregularity amplitude plays a great effect on the system dynamic stability. Thus cautious attention is still needed when selecting the line route and manufacturing the guideway. These conclusions could serve as a design guideline for the future high-speed application of linear HTS maglev bearing.

As a promising candidate for future high-speed transportation, the superconducting electrodynamic suspension (EDS) train have drawn a lot of attentions from the academic and industrial communities in the past decades. The dynamic response of EDS train is one of the key aspects that determines the safety and ride quality. In this work, the essential issue of EDS vehicle & x002F;guideway system dynamics is studied, including the magnet & x002F;rail interaction and the dynamic characteristics. The electromagnetic forces were provided by electromagnetic interaction between on-board superconducting magnet (SCM) and ground levitation & x002F;guidance coils in a null-flux superconducting EDS system. These forces were studied as a research premise for dynamic characteristics analysis of EDS train based on the vehicle & x002F;guideway coupling dynamics. A dynamic numerical model, with vehicle & x002F;guideway coupling dynamics of EDS system, was established to investigate its dynamic characteristics. The frequency and acceleration responses of the carbody in terms of the electromagnetic forces irregularity at different traveling speeds are presented and analyzed. The result indicates that superconducting EDS train can steadily run over the straight line at a speed of 600 & x00A0;km & x002F;h, meeting the riding comfort standard ISO2631.

Superconducting electrodynamic suspension (EDS) train has the unique advantages of excellent levitation and guidance stabilities, large levitation gap, and so on. All of these merits make it a promising candidate for the future ultrahigh-speed transportations. In order to explore the dynamic characteristics of the EDS system with a figure-eight-shaped coil (ground coil), this article transforms the complex electromagnetic field coupling between the superconducting magnets and ground coils into a reduced circuit relationship based on the dynamic circuit theory. Meanwhile, the motion characteristics are introduced to establish the field-circuit-motion-coupled model. In this article, a faster and more convenient semianalytical method was proposed to solve mutual inductance. First, the dynamic circuit model of a single-sided figure-eight-shaped null-flux EDS system was established. The magnetic coupling calculation was carried out between the onboard superconducting magnets and ground coils by a semianalytical method. Furthermore, the time-step iteration method was utilized to solve the induced current governing equation of the ground coil under different operating conditions. The energy method was employed to find the transient solution of the levitation force, guidance force, and drag force. Second, the field-circuit-motion-coupled model was validated by the experimental data of MLX01 on the Japanese Yamanashi testline. To investigate the influence upon the suspension and guidance caused by the different connection types of figure-eight-shaped coil, a cross-connected EDS train dynamic circuit model was built. Finally, based on the field-circuit-motion-coupled model, the essential parameters affecting the stability of the system were explored, and the characteristics of the system when vertical or lateral displacement occurs were calculated and analyzed. The achievements of this article can provide a reference for the design of the EDS train for future even higher speed transportation.

采用仿真分析与实验验证相结合的方法研究了横向磁通磁悬浮直线电机的自稳定能力及其电磁力特性.建立横向磁通磁悬浮直线电机三维电磁计算模型,利用有限元软件研究了电机次级电流分布以及电磁轨道几何参数、电气参数对电机性能的影响规律.研制实验验证样机,利用搭建的实验平台,测试在不同励磁电流大小、频率和悬浮气隙的条件下,电机次级所受到的驱动力、悬浮力、导向力的变化情况,并与仿真结果对比,验证有限元仿真模型的有效性与准确性,为横向磁通磁悬浮直线电机在轨道交通等领域的应用提供理论支撑.