Sub-sonic linear synchronous motors (LSMs) with high-temperature superconducting (HTS) magnets, which aim to accelerate to a velocity of 1200 km/h in the near-vacuum tubes of 0.001 atm for the Hyperloop, are newly introduced in this paper. By the virtue of the combination of LSMs and electrodynamic suspensions (EDSs) with HTS magnets, a large air-gap of 24 cm, low magnetic resistance forces of below 2 kN, and the efficient as well as practical design of propulsion power supply systems of around 10 MVA could be guaranteed at a sub-sonic velocity. The characteristics of the proposed LSMs with HTS magnets, in addition, are widely analyzed with theories and simulation results. Optimal design methods for LSMs and inverters, which account for more than half of the total construction cost, are introduced with design guidelines and examples for the commercialization version of the Hyperloop. At the end of the paper, in order to verify the proposed design models of the sub-sonic LSMs, two different test-beds—i.e., 6 m long static and 20 m long dynamic propulsion test-beds—are fabricated, and it is found that the experimental results are well matched with proposed design models as well as simulation results; therefore, the design methods constitute guidelines for the design of sub-sonic LSMs for the Hyperloop.

This paper presents a generalized source modeling method, referred here as distributed multilevel current (DMC) models, utilizing equivalent magnetizing currents as local point sources to describe material effects of commonly used magnetic components. Unlike existing numerical methods, which solve for the magnetic fields from Maxwell's equations and boundary conditions, the DMC-based method develops closed-form solutions to the magnetic field and force problems, while allowing tradeoffs between computational speed and accuracy using a multilevel structure to discretize geometry and minimize modeling errors in the neighborhood around the point sources. Typical DMC models for volume and surface current elements, permanent magnets, electromagnets, iron plate, and induced eddy currents are derived and validated by comparing their magnetic fields and forces with known (analytical, numerical, and/or experimental) solutions. Results of benchmark comparison demonstrate that the DMC methods reduce the computation time of magnetic fields and forces by several orders as compared to exact solutions numerically integrated from the Biot-Savart law and Lorentz force equation and finite-element analysis. The DMC models were experimentally applied to identify the EM coil position and PM magnetization of a commercial PM linear synchronous motor validating their effects on its torque ripple.

The Hyperloop has been developed using various technologies to reach a maximum speed of 1200 km/h. Such technologies include magnetic levitation technologies that are suitable for subsonic driving. In the Hyperloop, the null-flux electrodynamic suspension (EDS) system and superconducting magnets (SCMs) can perform stable levitation without control during high-speed driving. Although an EDS device can be accurately analyzed using numerical analysis methods, such as the 3D finite element method (FEM) or dynamic circuitry theory, its 3D configurations make it difficult to use in various design analyses. This paper presents a new design model that fast analyzes and compares many designs of null-flux EDS devices for the Hyperloop system. For a fast and effective evaluation of various levitation coil shapes and arrangements, the computational process of the induced electromotive force and the coupling effect were simplified using a 2D rectangular coil loop, and the induced current and force equations were written as closed-form solutions using the Fourier analysis. Also, levitation coils were designed, and their characteristics were analyzed and compared with each other. To validate the proposed model, the analyzed force responses for various driving conditions and the changed performance trend by design variables were compared with analyzed FEM results.

We developed a prototype of a high-Tc superconducting (HTS) linear synchronous motor (LSM) and evaluated its operational performances to obtain the preliminary design data for a test vehicle having a speed of 518.4 km/h. The HTS electromagnet was fabricated using a non-insulated (NI) GdBCO HTS coil, which was designed to produce a magnetomotive force of 300 kA-turns at a cooling temperature of 20 K. A two-stage Gifford-McMahon cryocooler was used to cool the electromagnet. The prototype was tested up to 2.7 kN sufficient to the required thrust of the test vehicle. The thrust characteristics shown by changing the operating conditions were also consistent with the simulation results. The HTS electromagnet was successfully operated during the test, and there was no fault in the NI HTS coils. Finally, we confirmed the design feasibility of HTS LSM for a test vehicle.

Maglevs are typically accelerated using electromagnetic propulsion and levitation. High-temperature superconducting (HTS) magnets along with electrodynamic suspension (EDS) and linear synchronous motors are one of the best options for Hyperloop. However, the strong magnetic fields generated by HTS magnets on the pods inevitably interact with the magnetic and conductive structures in the vacuum tubes, along with the tube itself, while the pods move through the tubes. This interaction is observed as a drag force on the pods, significantly reducing the propulsion efficiency. This study comprehensively analyzes the electromagnetic drag force (EDF) generated by HTS magnets on pods, which accounts for most of the drag forces faced by Hyperloop. Theoretical analysis and 3D FEA simulations are performed to analyze the propulsion forces with HTS magnets and all the drag forces on the pods. The EDF generated by AISI 1010 steel rebars in concrete guideways is even greater than the designed propulsion forces of 40 kN. Consequently, high-manganese (Hi-Mn) steel and insulated steel rebars are adopted and analyzed using 3D FEA simulations. The EDFs generated by the AISI 1010 steel and Hi-Mn steel vacuum tubes are determined by varying the distance between the HTS magnets and tubes at 50 and 1200 km/h, respectively; a minimum distance of 0.75 m is determined by a drag force below 8 kN within their operating velocities. Lastly, the total EDFs of the AISI 1010 steel and Hi-Mn steel tubes with EDS rails are obtained through the optimal design of rebars and tubes. The simulation results show that the total EDFs can be significantly reduced to below 10 kN (approximately 25% of the designed propulsion force after the levitation of pods).

Motivated by the growing interest in the Hyperloop system, we have researched a new mode of transportation that runs inside a vacuum tube at more than 1,000 km/h. A 2G high-temperature superconducting (HTS) magnet with a detachable cryocooling system has been developed to thrust and levitate the capsule train efficiently; it also reduces its weight. To compensate for performance losses due to increased operating temperature, the HTS coil shape of the on-board superconducting magnet is topologically optimized with respect to cost and performance. With a number of linear constraints converted from nonlinear superconductivity conditions, many linear topology optimization problems are solved, and then the most preferred design is determined by considering its shape, cost, and performance.