In this paper, the quantification of the external noise sources in high-speed trains is discussed. A thorough understanding of the underlying causes of noise generation in high-speed trains is needed to develop effective noise control measures. However, because high-speed trains produce a complex array of sounds, it is very difficult to determine each individual source of noise. In this study, the delay-and-sum beamforming method, which uses microphone arrays, was used to separate the noise sources and analyze the sound characteristics of high-speed trains. A new microphone array with 96 microphones was designed to measure the noise produced by high-speed trains. Performance verification tests were conducted to ensure the reliability of the results obtained from the array. Then, the system was used to measure the sounds produced by Korean high-speed trains traveling at speeds between 150 and 300 km/h. Sound maps were then produced using the beamforming technique. The study determined that the majority of the noise produced by the highspeed trains originated from the front nose, bogie, pantograph and inter-coach spacing. Finally, the beampower spectra of the aerodynamic noise sources originating in the front nose, pantograph and inter-coach spacing were deduced from frequency conversion. From these results, the aerodynamic noise characteristics of the major sources of noise in highspeed trains were determined.

This paper deals with efficient operation method for the electromechanical brake (EMB). A three-phase interior permanent magnet synchronous motor (IPMSM) is applied to the EMB operation. A current controller, speed controller, and position controller based on proportional-integral (PI) control are used to drive the IPMSM. Maximum torque per ampere (MTPA) control is applied to the current controller to perform efficient control. For MTPA control, the angle β is calculated from total input current, and the synchronous frame d–q axis current reference is determined by the angle β. The IPMSM is designed and analyzed with finite element analysis (FEA) software and current control is simulated by Matlab/Simulink using a motor model designed by FEA software. The simulation results were verified to compare with experimental results that are input current and clamping force of caliper. In addition, the experimental results showed that the energy consumption is reduced by MTPA.

This study describes the dynamic behavior of the HEMU-430X, the Korean next-generation high-speed train. The HEMU-430X was initially analyzed using VAMPIRE, a computer program that is used to examine the dynamics of railway vehicles, based on which it was expected to sway strongly at its tail end. This hunting motion was expected to disappear when the position of the yaw damper was changed. The dynamic behavior of the HEMU-430X was assessed in an on-track test performed using the protocols in the EN14363 standard and measuring the carbody, bogie and axle accelerations; the HEMU-430X was found to satisfy the safety criterion. The hunting motion appeared at speeds of 150, 350 and 387 km/h, and countermeasures such as changing the position of the yaw damper, installing carbody dampers, and increasing the damping coefficient of the yaw damper installed on the motor car containing the driver's cab were taken in order to reduce the vibrations. Ultimately, the highest test speed achieved was 421.4 km/h. Subsequently, it was found that the critical speed tended to decrease with mileage. This was attributed to excessive lateral damping and a revised design was proposed to solve this problem.

This paper deals with clamping force simulation and experimental result of the Electro Mechanical Brake (EMB) for the High-Speed-Train (HST). Three phase Surface Permanent Magnet Synchronous Motor (SPMSM) is applied to the clamping force control of EMB. At the initial development stage, Proportional Integral (PI) current control under synchronous d-q axis frame was applied to the SPMSM torque control. In addition, an anti-windup controller, which is advantageous for fast current tracking, is proposed to improve the torque output. Matlab/Simulink simulation results were compared with the experimental results measured by the clamping force sensors of the EMB test rig. The experimental results were verified compared to the brake design specification of the High-Speed Electric Multiple Unit-430 Experimental (HEMU-430X) train.

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