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 studies the output performance improvement of the spherical multi-degree-of-freedom (multi-DOF) motor. The multi-DOF motor is a motor that is designed to drive in multiple axes. Therefore, it is important that the shape of the motor should be fabricated to enable multi-axis driving when designing the multi-DOF motor. In addition, it is essential to consider the output density characteristics and stability characteristic analysis to reduce the volume of the multi-DOF motor and to operate of the motor in the stable range, respectively. In this paper, the structure and operating characteristics of the spherical multi-DOF motor with dual air gaps are described. In order to improve the output characteristics of the multi-DOF motor, characteristics analysis was performed according to the change of the number of the phases and pole pitch angles, and stability characteristic analysis for stable operation of the multi-DOF motor was performed.

This study proposes a damping control strategy for high-speed operation of a wave energy converter (WEC). The control strate-gy of WEC is based on the heave-motion (up/down motion) mechanism of buoy. The applied WEC system extracts power through damping control of the permanent magnet linear genera-tor, which is directly connected to the buoy. This study first ana-lyzed the mechanical dynamics of a WEC system. Further, a damping control method that could improve the extracted power for a wide speed range is examined. The results showed that the operating region could be expanded and the power extraction could be maximized using only the proposed software implemen-tation, without requiring additional hardware. The validity and benefits of the proposed control algorithm were experimentally verified using a down-scaled WEC model.

Research on Hyper Tube, a Korean high-speed HTS Maglev train, has reached the verification stage for actual operation, and electromagnetic dynamic characteristics analysis of the train is required accordingly. Depending on the winding type of the propulsion armature, the HTS magnet experiences the harmonic that causes AC loss. Beside the static thermal losses by thermal conduction, current leads et al., the AC loss should be take account for the thermal battery design depending on operation conditions. This study describes the AC loss analysis of the HTS magnet induced by the harmonic using the homogeneous T-A formulation widely used in recent. In consideration of acceleration and cruise conditions, the effect of the AC loss by harmonics on the capacity of the solid nitrogen thermal battery was discussed.

The Hyperloop is expected to surpass the speed limits of conventional ground transportation by minimizing air drag and friction resistance inside a vacuum tube, necessitating a stable magnetic levitation system. Among the various levitation methods being considered, electrodynamic suspension (EDS) combined with superconducting magnets (SCMs) capable of achieving a large airgap appears promising, as it can reduce infrastructure costs and enhance the Hyperloop's competitiveness. Although many studies have explored the use of SC-EDS in the Hyperloop, validating its performance at ultra-high speeds is challenging due to the need for a long test-bed, which consumes significant time and resources. This research aims to indirectly evaluate the highspeed performance of SC-EDS through static experiments. Magnetic flux density and levitation force of SCMs were measured using static experiments, and the performance of SC-EDS was assessed indirectly by calculating the induced current based on the experimental results. Additionally, each result was validated by comparing it with the numerical analysis result.

In this paper, the optimal design for a permanent magnet-assisted synchronous reluctance motor (PMA-SynRM) is proposed in terms of efficiency, maximum torque, and minimum torque pulsations. Design variables, objective functions, and constraints are selected for this optimal design, which is divided into two steps. Step I utilizes the pole/slot combination of the PMA-SynRM and winding methods. The chosen 4-pole/36-slot model with distributed winding maximizes the rated efficiency. In Step II, the optimal design of the stator parameters is obtained using the response surface method and the precise torque and torque ripple are calculated using the finite-element analysis (FEA). The proposed stator slot openings are minimized to minimize the air-gap flux leakage, and consequently, realize a smooth electromagnetic torque. Finally, a few FEA results are validated by experimental results.