• Journal of Power Electronics
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• 제14권4호
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• pp.742-753
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• 2014

In this paper, a new continuously and linearly controlled capacitive static VAR compensator is proposed for the automatic power factor correction of inductive single phase loads in 220V 50Hz power system networks. The compensator is constructed of a harmonic-suppressed TCR equipped with a new adaptive current controller. The harmonic-suppressed TCR is a new configuration that includes a thyristor controlled reactor (TCR) shunted by a passive third harmonic filter. In addition, the parallel configuration is connected to an AC source via a series first harmonic filter. The harmonic-suppressed TCR is designed so that negligible harmonic current components are injected into the AC source. The compensator is equipped with a new adaptive closed loop current controller, which responds linearly to reactive current demands. The no load operating losses of this compensator are negligible when compared to its capacitive reactive current rating. The proposed system is validated on PSpice which is very close in terms of performance to real hardware.

• Journal of Power Electronics
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• 제19권2호
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• pp.540-548
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• 2019

In this work a new configuration of E-core stator Switched Reluctance Motor (SRM) with permanent magnets and auxiliary windings embedded in the stator yoke is proposed. For the proposed configuration of SRM electromagnetic analysis is performed using Finite Element Analysis (FEA) based computer aided design package MagNet and to emphasize its merits a comparison is drawn with existing hybrid excitation configuration of SRM. In addition, the vibration characteristics of the motor are analyzed by performing modal and transient analysis using the ANSYS package. Results of the analysis reveals that the proposed configuration of SRM exhibits better electromagnetic and vibration characteristics and is capable of competing with the existing topologies in the variable speed market.

• 동력기계공학회지
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• 제18권3호
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• pp.87-92
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• 2014

This study is aimed at investigating the thermal behavior of immersion-cooled high power LED lighting engines. 3D CFD models have been generated for the numerical analysis. Five cases in terms of the configuration of LED chips have been explored for various passive cooling conditions of the lighting engine, i.e., the natural air convection with a lens, the natural air convection without a lens, the deionized water-immersion cooling condition with a lens. The numerical study reveals that the deionized water-immersion cooled lighting engine has nearly twice better thermal performance than the natural air convection cooled lighting engine containing a lens. The investigation has also demonstrated that the four chips configuration has the better thermal performance than the single chip configuration.

• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1483-1493
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• 2018

Recently, more power facilities are needed to cope with the increasing electric demand. However, the additional construction of generators, transmission and distribution installations is not easy because of environmental problems and citizen's complaints. Under this circumstance, a microgrid system with distributed renewable resources emerges as an alternative of the traditional power systems. Moreover, the configuration of power system changes with more DC loads and more DC installations. This paper is written to introduce an idea of a genetic algorithm-based solution to determine the optimal capacity of the distributed generators depending on the types of system configuration: AC-link, DC-link and Hybrid-link types. In this paper, photovoltaic, wind turbine, energy storage system and diesel generator are considered as distributed generators and the feasibility of the proposed algorithm is verified by comparing the calculated capacity of each distributed resource with HOMER simulation results for 3 types of system configuration.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.406-408
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• 2003

As power demand increases gradually, the call for underground transmission system increases. But it is very difficult and high in cost to construct new ducts and/or tunnels for power cables in metropolitan areas. HTS (High Temperature Superconducting) cable has the several useful characteristics such as increased power density. Therefore HTS cable can allow more power to be moved in existing ducts, which means very large economical and environmental benefits. In this paper, we investigate the status of korean power system and underground transmission system. Based on this, the feasibility study on applying 22kV class HTS cable to korean power system is carried out and then we propose the new power system configuration of metropolitan area with 22kV class HTS cable.

• 전기학회논문지
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• 제60권4호
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• pp.711-716
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• 2011

This paper defines a generator reactive reserve considering power system network. Conventional generator reserve is calculated by the difference between the maximum reactive power output of generator and the current reactive power of generator. However, all generators could not affect on the whole power system. Thus, the effective generators should be selected by sensitivity analysis. The sensitivity depends on network configuration is the relation between generator reactive power outputs and reactive power loads. Using the sensitivity, the effective generator reactive reserve can be calculated.

• 전자공학회논문지
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• 제50권12호
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• pp.56-62
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• 2013

우리는 MOSFET Layout 단계에서 Multiplier 구성을 통한 Common centroid layout 방식을 사용한 무선 전력 전송 용 CMOS 정류회로를 제안한다. 제안하는 정류회로는 기존의 다이오드를 사용하지 않은 Cross-coupled MOSFET 정류회로로 13.56 MHz에서 동작한다. 전력 소모를 최소화하고, 높은 주파수까지 동작하기 위하여 Full bridge 정류회로에서 효율을 높이기 위한 비교기를 제거하였다. Layout 단계에서 Multiplier 구성을 통한 Common centroid layout 방식은 Chip-layout 상에서 MOSFER의 Finger에 의해 길어진 연결 선로에 존재하는 기생 직렬 저항과 병렬 Capacitor에 의해 발생하는 시간 지연을 줄이기 위해 고안되어, 천이 시간을 줄여 Cross-coupled 구조의 On-상태에서 Off-상태, 혹은 그 반대의 상태 변화를 빠르게 한다. 이는 빠른 상태 변화 시간으로 인해 전력 변환 효율을 증가시킨다. 본 정류회로는 $0.11{\mu}m$ CMOS 공정으로 제작되었으며, 전력 변환 효율은 최대 86.4%로 측정되었으며, 600 MHz 이상까지 높은 전력 변환 효율을 가지며, 이는 현재 발표된 것 중, Cross-coupled 구성을 기반으로 한 정류회로 중 가장 높은 성능을 가진다.

• 전력전자학회논문지
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• 제19권1호
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• pp.31-40
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• 2014

This paper describes an optimal configuration for multi-central inverters in a medium-voltage (MV) grid, which is suitable for large-scale photovoltaic (PV) power plants. We theoretically analyze a proposed common-mode equivalent model for problems associated with multi-central transformerless-type three-phase full bridge(3-FB) PV inverters employing two-winding MV transformers. We propose a synchronized PWM control strategy to effectively reduce the common-mode voltages that may simultaneously occur. In addition, we propose that the existing 3-FB topology may also have the configuration of a multi-central inverter with a two-winding MV transformer by making a simple circuit modification. Simulation and experimental results of three 350kW PV inverters in a multi-central configuration verify the effectiveness of the proposed synchronization control strategy. The modified transformerless-type 3-FB topology for a multi-central PV inverter configuration is verified using an experimental prototype of a 100kW PV inverter.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.503-505
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• 2008

The purpose of the current study is to examine the aerodynamic characteristics of two hypersonic vehicles in near space. One is derived from waverider shape, and the other from liftbody. The objective of this study are threefold. The first is to creat an computational database for hypersonic vehicle configurations. The second is to examine the effects of individual vehicle components on hypersonic configurations and to determine the differences in aerodynamic characteristics that result from integrating all vehicle components. The third objective is to evaluate the controllability of each of the fully integrated vehicles and the effectiveness of the control surface design. These objectives were accomplished using DSMC solutions and aerodynamic code developed in Northwestern Polytechnical University. The results are analyzed also in three sections. First, the results of the waverider shape and liftbody shape without integrated vehicle components are presented. Second, the results of adding aircraft components to the waverider shape and liftbody shape are presented. Finally, the aerodynamic characteristics of the fully integrated waverider-derived configuration and liftbody-derived configuration are examined and compared with those of the pure waverider shape and liftbody shape. Comparation between fully integrated waverider-derived configuration and liftbody-derived configuration are also presented in this paper.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1208-1210
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• 1999

Design & operation power systems for meeting increase of electric power demand is becoming more difficult and complex. Some of limitations of conventional technology can be broken through by the application of superconductivity technology. This paper presents a new concept & image for the configuration of superconducting power system which has introduced superconducting(SC) generator, cable, transformer, fault current limiter(SFCL), SMES, etc. Engineering evaluation of each power apparatus and its assessment of application to power system were conducted. Futhermore, it is pointed that superconducting power system require a new operating condition. This is, SFCL should play a important part of quenching current level coordination to prevent the other superconducting devices from quenching. Its designing & operating condition including SFCL was discussed in viewpoint of quenching current level and insulation coordination of SC coil.