The wheelset is an important part that affects the dynamics of railway vehicles. The main purpose of the wheelset is to solve the problem of stability, curve performance, comfort, and wear. A conventional railway vehicle adopts rigid-axle wheelset (RW) due to the self-centering mechanism. On the other hand, independently rotating wheels (IRWs) have not been widely applied in the railway industry, since they do not generate any self-centering mechanism. It creates excessive wear, and derailment may occur. However, the IRWs have excellent curving performance compared with the RWs, and it enables realizing a low-floor structure that is convenient for passengers to get on and off. The recent active control technology has made it possible to generate a centering force in the IRWs. There are still many obstacles for the practical use of this technology, and it is necessary to verify the control strategies through various test methods. In this paper, an analytical model is derived, and an active control strategy is studied. To verify the validity of the active control strategy, a novel hardware-in-the-loop simulation (HILS) configuration using a real-time model and a motor-generator set are proposed. INDEX TERMSActive control, hardware-in-the-loop simulation (HILS), motor control, independently rotating wheels (IRWs), railway vehicle, rigid-axle wheelset (RW).

Owing to the development of electric vehicles (EVs), research and development are underway to minimize torque ripple in relation to vibration and noise in EV motors. Although there are various ways to reduce torque ripple, this study analyzes the torque ripple, cogging torque, total harmonic distortion (THD), and magnetic flux density distribution for the three rotor shapes of interior permanent magnet synchronous motors, which are widely employed in EVs. To reduce the torque ripple while retaining the required average torque, the barrier shape is optimized, and wedge skew is applied. First, regarding the rotor barrier shape, torque ripple is primarily reduced by designing the rotor barrier shape with the response surface method, which is an experimental design method. Additionally, the wedge skew shape considering the bidirectional rotation and fabrication was applied to the stator shoe as a step and analyzed using three-dimensional finite element analysis. When designing the wedge skew, the layer subdivision according to the axial length, wedge skew diameter, and wedge skew position was analyzed and improved. The torque ripple reduction method in this paper can be applied not only to motors for EVs or Hybrid EVs (HEVs) but also all types of permanent magnet synchronous motors.

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This paper is a study of the eddy current brake designed to replace the air brake of railway application. The eddy current brake has the advantage of being able to take a high current density compared to the other application because this brake is used for applying brakes to the rolling stock for a shorter amount of time. Also, this braking system has the merit of being able to take a high current density at low speed rather than at high speed, because the heat generated by the low speed operation is less than that of the high speed operation. This paper also presents a method of improving the output torque of the eddy current brake at low speed operation through a change of the winding as well as the basic design.