With the continuous increases of the train speed, the braking device that relies on the wheel-rail adhesion has approached its acceptable speed limit. Compared with traditional friction brakes, eddy current brakes (ECBs) have the advantages of non-wheel-rail contact, fast response, low noise, wide application range, and no pollution. This study describes an ECB with AC excitation based on Faraday's law. The two-dimensional analytical model of ECB is established by the sub-domain method. Then, the experiment system of rail ECB is designed and built to test the braking characteristics. The authenticity of mathematical model is verified by experimental results. The research indicated that braking force increased at first and reached a maximum value, then slowly decreased with the increase of speed, while normal attractive force was always reduced. This characteristic matches the requirements of high-speed trains with large braking force and low normal force, which makes it a great option for auxiliary braking mechanism in the high-speed trains.

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.

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.

The paper proposed double-sided superconducting linear generator with YBCO tape windings. An analytical model of linear generator was developed based on electromagnetic field theory. A parameter-scanning method is used to search for optimal dimension parameters with the purpose of minimizing the non-sinusoidal components of the induced voltage curve. The results obtained show a significant improvement in the quality of air-gap magnetic field, and reduction of the higher harmonic in voltage wave obviously. The induction voltage in the generator coils at the speed of 130 m/s are studied. Finally, the feasibility of the superconducting linear generator was analyzed and confirmed.

This paper describes an eddy current brake (ECB) device consisting of AC excitation and ferromagnetic railway. The braking force can be generated with non-contact and low noise caused by the reaction between the eddy current and excitation current. In this paper, the structure of the brake is introduced detailedly. In addition, the three-dimensional finite element analysis (FEA) model of ECB is established. Meanwhile, the experiment system of the rail ECB is built to study the braking characteristics. The validity of FEA simulation is verified by experimental results. It is found that with the increase of speed, the braking force increases linearly to a maximum value first, then slowly decreases, while the normal attractive force decreases continuously. The braking characteristic matches the requirements for the high-speed running trains which need large braking force and low normal force in the deceleration process, so it can be used as an auxiliary braking method in the high-speed railway.

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.

High temperature superconducting (HTS)-coated conductors show various advantages in practical applications because of its zero resistance and large current capacity. Owing to the superior properties of HTS material in high magnetic fields, the HTS linear synchronous motor (LSM) is able to output high performance at relatively large air gap. Many experiments and prototypes have been implemented, which requires great consumption of HTS-coated conductors. In this paper, an analytical model of coreless HTS LSM was established and the magnetic flux density dependence of the critical current density of HTS-coated conductors was taken into account. An HTS-generalized racetrack coil was introduced to the analytical model for easy parameterization. A small scale prototype of the LSM which has a coreless stator and a HTS secondary was manufactured to validate the analytical model. It is indicated that the calculations have a good agreement with the experiments. As an application of the analytical model, an optimization task of the HTS LSM was carried out to improve its performances.

High temperature superconducting stacks of tapes can also trap high magnetic fields which makes them a promising candidate for a multitude of electrical applications. In this paper, we aim to replace the traditional permanent magnet in linear synchronous motors by magnetized tape stacks. To study the characteristics of how traveling magnetic fields cause trapped fields to decay, stacked tape configurations comprised of two parallel columns were assembled, tested, and modeled computationally. The decay characteristics of the trapped magnetic field at different stator current amplitudes and different frequencies were measured by a homemade measurement system. A two-dimensional model including stator and stacks of YBCO coated conductors was constructed to investigate the related electromagnetic properties. The mechanisms linking the magnetic ac losses to the trapped magnetic field decay is discussed. Lastly, we present three effective methods to reduce trapped field decay which include: placing superconducting shielding layers at the sides; inserting Permalloy pieces in between; and increasing the number of stacked layers.

The stack of HTS tapes can be magnetized as a powerful magnet like permanent magnet. It has been investigated extensively in many papers, but there are few studies about its performances in practical travelling-wave magnetic field. In our previous work, the attenuation characteristics traveling-wave magnetic field of the trapped magnetic field of a stacked-tape magnet used in linear synchronous motor has been studied. The force characteristics between stacked tape magnets and traveling-wave magnetic field are the most important parameters for high temperature superconducting linear synchronous motors (HTSLSM). In order to identify the performance and force characteristics of the HTSLSM, a simplified 2D finite element model about HTSLSM has been built up in this paper, and an experiment test system has been constructed to measure the force characteristics with different stator currents and stacked layers. The experimental result shows an agreement with simulation result. Based on this model, the influence of the number of stacked magnets on thrust was also investigated. The results help better understand the feasibility of a novel HTSLSM using stack of HTS tapes.