• The Transactions of The Korean Institute of Electrical Engineers
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• 제59권3호
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• pp.575-580
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• 2010

This paper is to design an optimum power conversion device for the system required for development of a low cost 3-phase power inverter. For this purpose, in order to meet with endurance required by the industry, failure mode is standardized to guarantee lifetime of a power semiconductor by monitoring real time power loss and to facilitate failure mode analysis. As normality of heat loss of a power semiconductor is identified remaining in a certain range by comparing heat rise slope between that is calculated by using average current or average loss and that is measured at a heat sink, its feasibility is confirmed by experiment.

• The Transactions of The Korean Institute of Electrical Engineers
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• 제56권3호
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• pp.457-464
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• 2007

Micro-Grid comprising Micro-Sources supplying several $kW{\sim}MW$ power to local customers is environmentally friendly and reliable. This paper deals with the development of simulation models of Micro-Grid on the PSCAD/EMTDC platform for analyzing various aspects of the interaction of the Micro-Grid. The developed switching level model adopts the space vector PWM. Both switching level and power frequency Micro-Source models are developed, which shows that power frequency modeling is sufficient for analyzing the phenomena of interest. Control characteristics of the Micro-Sources with the parameter and load power variation are analyzed for power quality enhancement. The simulation results show that the developed models are effective for studying Micro-Grid.

• Proceedings of the KIPE Conference
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.215-218
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• 2000

The windup phenomenon appears and degrades control performance when a controller with integrating action is used and the plant input is limited. An anti-windup integral -proportional(IP) controller is proposed for the variable-speed motor drives and it is experimentally applied to the speed control of a vector-controlled induction motor driven by a pulse width modulated (PWM) voltage source inverter(VSI). Although the operating conditions like motor load and speed command is changed under the limited plant input it is experimentally verified that the speed response has much improved performance such as no overshoot and fast settling time and the maximum plant input is also effectively utilized.

• Proceedings of the KIPE Conference
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.186-190
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• 2000

This paper propose a "Active common-mode voltage damper circuit" that capable of a suppression of a common-mode voltage produced in the PWM VSI. The four level half-bridge PWM inverter circuit and common-mode transformer are incorporated into the "Active common-mode voltage damper" the design method of which is presented Effect of "Active common-mode voltage damper" in this paper verifies a propriety and effectiveness in 2.2[kW] induction motor drive using IGBT inverter. Experimental results show that "common-mode voltage damper" makes contributions to reducing a high frequency leakage current and common-mode voltage.leakage current and common-mode voltage.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제15권9호
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• pp.753-763
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• 1990

This paper proposes a new current control strategy for current regulated VSI-PWM lnverter. The conventional hysteresis control method has good dynamic response, but the switching frequency in lower region are high because it does not optimise switching patterns. Proposed current control strategy can optimize switching patterns. As regulater, three level comparator are used, the output of comparator select appropriate inverter output voltage vectors via switching table stored in EPROM. The simulation and experimental results in comparison to conventional hysteresis strategy are presented and discussed.

• Proceedings of the KIPE Conference
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• 전력전자학회 2009년도 정기총회 및 추계학술대회 논문집
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• pp.228-230
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• 2009

본 논문에서는 전류형 인버터(CSI)와 전압형 인버터(VSI)를 조합하여 유도성 부하에 정현파 전류를 공급하는 시스템에서, LC 소자를 추가함으로써 전압형 인버터의 VA rating을 줄일 수 있는 방법을 제안하였다. 전력제어용 스위칭 소자인 SCR은 대용량인 장점이 있는 반면에 턴오프 제어가 되지 않고, 비선형 특성으로 인해 고조파가 발생한다. 이러한 단점을 개선하기 위해 전압형 인버터를 사용하여, SCR를 OFF하고 부하에 정현파 전압/전류를 제공한다. 또한, 출력단에 수동 LC 필터를 추가하여 전압원 인버터의 VA rating을 저감시키는 구조를 연구하고 이를 Psim을 이용한 시뮬레이션을 통해 검증하였다.

• Journal of Korean Society for Quality Management
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• 제32권4호
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• pp.156-168
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• 2004

This research investigates the statistical efficiency of variable sampling size & sampling interval(VSSI) $\bar{X}$ charts under two assignable causes. Algorithms for calculating the average run length(ARL) and average time to signal(ATS) of the VSSI $\bar{X}$ chart are proposed by employing Markov chain method. States of the process are defined according to the process characteristics after the occurrence of an assignable cause. Transition probabilities are carefully derived from the state definition. Statistical properties of the proposed chart are also investigated. A simple procedure for designing the proposed chart is presented based on the properties. Extensive sensitivity analyses show that the VSSI $\bar{X}$ chart is superior to the VSS or VSI $\bar{X}$ chart as well as to the Shewhart $\bar{X}$ chart in statistical sense, even tinder two assignable causes.

• Proceedings of the KIEE Conference
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.1104-1107
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• 1992

Voltage controlled current regulated PWM(pulse width modulation) of VSI (voltage source inverter) is proposed. Adopting one degree of freedom, the voltage, the current controller shows much more improvement than conventional ones not using this method. The voltage controller or this proposal needs load's parameters, torque value, rotational speed. This voltage controller is located at converter part which links AC source and DC bus. With this proposed method, duty ratio of the inverter's switching is nearly unity for all speed and torque range. Hence, this method gets many advantages such as reducing current ripple, thermal loss, and noises and improving control performances. Theoretical approach to this voltage-current controller is performed, and the results are presented.

• Proceedings of the KIEE Conference
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.1147-1149
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• 1992

A novel 3$\phi$ ZVS PWM VSI topology employing a simple dc bus subcircuit that provides soft switching commutations is proposed in this paper. The main advantage of the proposed inverter commutation schem is that the dc bus subcircuit is activated only when required, that is, when dictated by the respective PWM. Detailed analysis is provided and simmulation results are presented to verify the principles of operation of the proposed inverter schem.

• Proceedings of the KIEE Conference
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.280-282
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• 2005

Micro-source units having power ratings in thousands of watts can provide even higher reliability and fuel efficiency than the conventional large scale units. These units are also clustered with loads creating micro-grid services to customer sites such as office buildings, industrial parks and homes. Micro-sources adopt voltage source inverter to ensure the power quality of sensitive loads. This paper deals with the connection of micro-sources into the system grid. Modeling and simulation of the grid connected micro-sources at the power frequency range are investigated. Simulation results show that the micro-grid system with two micro-sources has good dynamic characteristics.