• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
• /
• pp.287-296
• /
• 2011

Turnout is a mechanical installation enabling railway trains to be guided from one track to another at a railway junction. A movable nose crossing frog is a device used at a railway turnout to eliminate the gap at the common crossing (High manganese, block, assembly crossing)which can cause impact damage, noise and vibration. Our government has a plan speed up of conventional line to 250km/h semi-high speed. We had already developed flexible turnout with fixed crossing(High manganese) and SFC fastening system can cover in the semi-high speed line In this study is about development of the movable nose crossing turnout available Semi-high speed line on concrete track. This paper describes about geometry, attack angle, bending stress at the nose, switching force, safety of continuous welded long rails. This movable nose crossing turnout is expected greatly increases passing speed of turnout in national railway.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1999년도 하계종합학술대회 논문집
• /
• pp.239-242
• /
• 1999

In this paper, we report the process/device design of high-speed, high-voltage SOI smart power IC for mobile communication system, high-speed HDD system and the electronic control system of automobiles. The high voltage LDMOS with 70V breakdown voltage under 0.8${\mu}{\textrm}{m}$ design rule, the high voltage bipolar with 40V breakdown voltage for analog signal processing, the high speed bipolar with cut-off frequency over 20㎓ and LDD NMOS for high density were proposed and simulated on a single chip by the simulator DIOS and DESSIS. And we extracted the process/device parameters of the simulated devices.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2001년도 전력전자학술대회 논문집
• /
• pp.608-611
• /
• 2001

This paper is indicating the problems, which are the conduction loss on the high frequency transformer, the protection of rectification diode as the snubber loss and the stress of switching main devices, as be made high current and high speed in the phase-shift switching full-bridge DC-DC converter is used the power supply's main circuit of high capacity. In this paper, to improve those problems, it is proposed that is the resonant circuit auxiliary can be reduced conduction losses and stabilized output control. And, it is constructed prototype of the power supply as the result of computer simulations.

• 전력전자학회논문지
• /
• 제6권2호
• /
• pp.191-201
• /
• 2001

현재 산업용, 가정용 전동기의 수요는 급증하고 있다. 이는 스위칭 소자와 제어기술의 현저한 진보가 있었기 때문이며 이중 BLDC 전동기의 사용이 증가하고 있다. 그러나 일반적으로 사용되고 있는 3상 BLDC 전동기 맥동토크가 크고 속도변화에 민감하며 높은 속도에 적용하는데 한계가 있다. 이러한 문제를 해결하기 위해서는 전동기의 상과 극수, 슬롯수를 증가시켜야만 한다. 그래서 현재 다상 BLDC 전동기의 연구가 진행중에 있다. 하지만 다상 BLDC에서는 높은 스위칭 주파수로 인해서 일반적으로 쓰고 있는 히스테리시스 전류제어기를 제안하였고 7상 BLDC 전동기에 적용하여 시뮬레이션과 실험을 통해서 타당성을 입증하였다.

• Journal of Power Electronics
• /
• 제7권3호
• /
• pp.222-232
• /
• 2007

This paper presents the application of a single phase AC-to-DC converter using a three-phase series parallel (SPRC) resonant converter to variable speed dc-drive. The improved power quality converter gives the input power factor unity over a wide speed range, reduces the total harmonic distortion (THD) of ac input supply current, and makes very low ripples in the armature current and voltage waveform. This soft-switching converter not only possesses the advantages of achieving high switching frequencies with practically zero switching losses but also provides full ranges of voltage conversion and load variation. The proposed drive system is the most appropriate solution to preserve the present separately excited de motors in industry compared with the use of variable frequency ac drive technology. The simulation and experimental results are presented for variable load torque conditions. The variable frequency control scheme is implemented using a DSP- TMS320LF2402. This control reduces the switching losses and current ripples, eliminates the EMI and improves the efficiency of the drive system. Experimental results confirm the consistency of the proposed approach.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 1999년도 전력전자학술대회 논문집
• /
• pp.663-666
• /
• 1999

This paper describes a three-phase converter with high power factor using a scheme of discontinuous current mode(DCM). The proposed system can replace the conventional diode bridge with step-up chopper which is used as a converter for adjustable speed drive. In this system, the current of reactor is zero at turn-on instance because of operation in DCM, while the switch turns off at the instance of maximum current. A soft-switching scheme with lossless snubber was proposed. Therefore, a zero-voltage switching at turn off can be achived by lossless snubber and zero-current switching at turn on can be obtained by operating under DCM. A theoretical analysis and computer simulations with PSpice were done to verify the operation of the proposed system. Also a prototype of hardware system was built and tested for verifying the feasibility of proposed system.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2002년도 하계학술대회 논문집 B
• /
• pp.838-840
• /
• 2002

Most adjustable-speed drives (ASDs) designed to operate 220[V] induction motors incorporate voltage-source inverters (VSIs), which create motor voltages at high switching frequencies. The motor leads used to connect an ASD to a motor can behave like transmission lines for voltage pulses, which can be reflected at the motor terminals. The resulting oscillatory transient, known as the long-lead effect, can stress and consequently degrade the stator insulation system of a motor. This paper describes the results of tests to 1) determine the correlation between peak motor voltage and the length of motor leads and 2) determine the correlation between peak motor voltage and the switching frequency of the ASD

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2011년도 춘계학술대회 논문집
• /
• pp.918-923
• /
• 2011

On AC railway systems, the neutral sections are installed in front of substations and sectioning posts in order to avoid crash between power that have differing phases. In case railway vehicles pass through these neutral sections, it is necessary for them to switch to coasting driving by notch-off. This may reduce speed of the vehicles, resulting lowered train operation efficiency. The usage of automatic power switching systems makes it possible to pass neutral sections at notch-on, enhancing operation efficiency so that it is appropriate for high-speed railway applications. This paper introduces a simulator that assesses efficiency of automatic power switching systems in neutral sections. The is composed of a power supply system, electric railway vehicles, thyristor switches, and traction motors.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2008년도 제39회 하계학술대회
• /
• pp.1779-1780
• /
• 2008

This paper presents a switching system of speed controller between PI (Proportional_Integrator) and P_LPF (Proportional_Low pass filter) to improve overshoot and slow settling time in DC motor. When the integrator is saturated in the PI controller, the error signal is integrated continuously. For preventing the state, the Anti-windup scheme is proposed. But the Anti-windup scheme dose not show stable characteristics in the whole speed command section after tuned a gain. By using P_LPF switching system these problems are improved and there is no need to tune of user hereafter, when the integrator is saturated. The proposed method is verified by the simulation results using MATLAB SIMULINK.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제55권1호
• /
• pp.9-15
• /
• 2006

The conventional hysterysis band DTC(Direct Torque Control) strategy have relatively high torque ripple at low speed and variable switching frequency according to motor speed even though it provides a fast torque response with very simple scheme consisted with only two hysteresis band comparators and a switching table for torque and flux control. In this paper, author proposed a new DTC scheme based on the torque slope and reference voltage control. The new scheme can maintain the minimized torque ripple and constant switching frequency. Experimental tests carried out with an 1.5kW induction motor drive system show improved dynamic characteristics and prove the feasibility of proposed strategy.