• Proceedings of the KSR Conference
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• 2010.06a
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• pp.227-233
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• 2010

This paper treats the method to build up Motor drive-circuit using semi-conduct control part like power transistor, MOSEFT and refers to the operation theory, forward, reverse rotation control and speed control method which is changed by PWM. And also, this paper mention to the basic principle of DC Motor and various Motor control method using micro-processor.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.2
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• pp.149-156
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• 1990

In DC electric railway systems, the feeding currrnt is not permitted to flow backward in almost all the substations and the pantograph voltages at the regenerating cars rise extremely by the voltage drop of the resistance of the feeder line. In order to prevent the overrise of the pantograph voltage in power regenerating cars, the squeezing circuits for the regenerative current are equipped and this leads to double losses, which are an extra worn-out of the brake-shoes and an ineffective use of regenerative power. In this study, the insertion of resistors in the feeder line system is proposed as a possible method for the effective utilization of the regenerative power in the electric railways. Also it is investigated how the output voltages of substations affect the effective use of regenertive capability. The investigation results show that the energy savings and the reduction of the worn-out of the brake-shoe can be achieved at the same time by the insertion of resistors in the feeder line system.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.547-551
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• 2003

This paper presents the magnetic fields shielding properties of the light rail transit which are produced by the ripple-shaped currents in the power lines. To analyze these properties, the equivalent circuit model of the DC power supply system at the light rail transit system was induced by MATLAB-SIMULINK, and with the calculated results of the ripple-shaped currents, the magnetic fields shielding properties of the light rail transit were analyzed. The results are as follows. First The frequency of the ripple-shaped currents is 200[Hz] and its magnitude is 1.5[A]. Second the magnetic fields produced by the ripple-shaped currents of the DC power supply systems are well shielded by the aluminum made body of the light rail transit.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.646-658
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• 2006

In this paper, the details of electric traction voltages which are widely used for metro and mainline trains are presented. The problems encountered in catenaries, pressure of the pantograph pan, catenary contact cross sectional area, materials etc are well covered. Catenary height from the rail for main line, bridges, sheds etc is discussed. The catenary running details and switching of one catenary to another are explained. The dead zones in 3 phase grid as well as in DC are presented here. The pantograph structure, blades, shoes etc. for AC/DC EMUs are dealt. The schematic diagram for electrification systems used for railways are given and explained with typical electrical parameters of Indian Railways.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.2
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• pp.54-61
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• 2015

In 3-phase 4-wire inverter, the unbalanced loads cause to increase the neutral current which brings the voltage deviation between the split dc-link capacitors to be larger. In order to solve this problem, a neutral leg is provided additively to the ordinary inverter circuit and the associated control methods are devised. This paper proposes a new neutral-leg controller based on a PR controller and shows relatively good performance even under unbalanced linear loads and nonlinear loads. The proposed control strategy illustrates its effectiveness under the various operating conditions through simulation works.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.619-625
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• 2008

Electrical Power supply System conditions of korea high speed train consists of main transformer, four AC-DC PWM converter of Auxiliary Block, Battery Charger in Power Car and Trailer Car, Trailer Inverter, Auxiliary inverter. Main transformer, at nominal voltage of 25kv supplied to secondary winding nominal output Voltage 383Vac, The Auxiliary block consists of AC-DC converters for generating 670VDC power, Auxiliary inverters for ventilation and air compressor, Trailer car inverter provide three phase power supplies at 440Vac for air conditioning and heating. The Battery charger Trailer and Power car supplies 72VDC all necessary equipment to energize the trainset equipment and suppy essential control. This Paper introduces the combined test results of the power supply system for korea high speed train. The main purpose of this combined test is to verify the performance of the power supply system that is designed to operate up to full load test.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.269-274
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• 2008

The Seoul subway is acting the center of public transportation after the opening of the first line on August 15, 1974. and the subway line of the DC traction system is running and building to the ninth line. However, the main insulation parts used in overhead contact line are now imported from overseas products. Therefore, this paper considers domestic manufacture technology, supply easiness and economic effectiveness of insulation products and reviews the safety of support insulator used in rigid conductor line, stem insulator used in movable bracket and AC/DC different phase section insulator that localization development is necessary.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.260-262
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• 2019

본 논문은 철도 차량용 보조전원 장치의 부피 저감을 위하여 펄스 폭 제어가 포함된 공진형 LLC 컨버터를 제안한다. 철도 차량용 보조전원 장치는 가선에 연결되어 객차의 각종 전원을 공급하는 장치로써 객실 내의 전원과 절연이 필수적이다. 따라서 고효율의 절연형 DC/DC 컨버터인 LLC 컨버터가 적용되어 있으나, 가선의 큰 입력전압 변동에 대응하기 위해 스위칭 주파수의 변조 폭이 넓어질 뿐 아니라 제어 난도가 증가하는 단점을 가진다. 이러한 LLC 컨버터의 단점을 보완하기 위해 Boost+LLC 또는 Buck+LLC 컨버터의 두 단계의 전력변환을 통해 Boost 또는 Buck 컨버터가 LLC 컨버터의 입력전압을 제어하며, LLC 컨버터는 항상 공진 주파수에서 동작하도록 제어하는 시스템이 주로 사용된다. 본 논문은 3레벨 LLC 컨버터에 펄스 폭 변조를 적용하여 입력전압 제어를 달성하며, 이를 통해 기존의 시스템보다 부피 저감을 달성하는 방안을 제안한다. 제안된 방법은 전력변환 모의해석 프로그램인 PSIM 및 Matlab을 통해 검증되었다.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.334-335
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• 2019

본 논문은 전기철도용 전력보상장치로 사용되는 단상 3레벨 인버터를 제작하였으며, 단상 3레벨 인버터의 유 무효 전력제어기를 설계하였다. 단상 3레벨 인버터는 유 무효전력을 제어하기 위해 가상 동기좌표계 축 상에서 PI 제어기를 통해 전류제어를 수행한다. DC 링크 제어는 3레벨 인버터를 고려할 때 DC 링크 전압의 상단부와 하단부 전압의 평형상태를 유지하기 위해 제어하는 밸런싱 제어기를 포함한다. 10kVA 단상 3레벨 인버터 프로토타입을 설계하였으며, 안정한 유 무효전력제어 특성 실험 결과를 통해 단상 3레벨 인버터의 설계 및 제어 동작의 타당성을 검증하였다.

• Journal of the Korean Institute of Gas
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• v.13 no.2
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• pp.1-6
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• 2009

With respect to a given structure, a stray current is to be defined as a current flowing on a structure that is not part of the intended electrical circuit. Most often DC-powered traction systems like railroads and tramlines are responsible for large dynamic stray currents. This type of stray current is generally results from the leakage of return currents from large DC traction systems that are grounded or have a bad earth-insulated return path. At the place where the current leaves the rail and metallic structures, electrolytic corrosion may take place. This paper investigates the domestic conditions on the electrolytic corrosion protection of buried metallic structures adjacent to DC traction systems by survey.