• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.195-204
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• 2015

In this paper, the development of a cost-effective active power filter/uninterruptible power supply (APF/UPS) system with seamless mode transfer is described. The proposed scheme employs a pulse-width-modulation (PWM) voltage-source inverter and has two operational modes. First, when the source voltage is normal, the system operates as an APF, which compensates for the harmonics and power factor while boosting the DC-link voltage to be ready for the disturbance, without an additional DC charging circuit. A simple algorithm to detect the load current harmonics is also proposed. Second, when the source voltage is out of the normal range (owing to sag, swell, or outage), it operates a UPS, which controls the output voltage constantly by discharging the DC-link capacitor. Furthermore, a seamless transfer method for the single-phase inverter between the APF mode and the UPS mode is also proposed, in which an IGBT switch with diodes is used as a static bypass switch. Dissimilar to a conventional SCR switch, the IGBT switch can implement a seamless mode transfer. During the UPS operation, when the source voltage returns to the normal range, the system operates as an APF. The proposed system has good transient and steady-state response characteristics. The APF, charging circuit, and UPS systems are implemented in one inverter system. Finally, the validity of the proposed scheme is investigated with simulated and experimental results for a prototype APF/UPS system rated at 3 kVA.

• Journal of Power Electronics
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• 제14권1호
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• pp.48-60
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• 2014

Multilevel inverters have been widely used for high-voltage and high-power applications. Their performance is greatly superior to that of conventional two-level inverters due to their reduced total harmonic distortion (THD), lower switch ratings, lower electromagnetic interference, and higher dc link voltages. However, they have some disadvantages such as an increased number of components, a complex pulse width modulation control method, and a voltage-balancing problem. In this paper, a novel nine-level reduced switch cascaded multilevel inverter based on a multilevel DC link (MLDCL) inverter topology with reduced switching components is proposed to improve the multilevel inverter performance by compensating the above mentioned disadvantages. This topology requires fewer components when compared to diode clamped, flying capacitor and cascaded inverters and it requires fewer carrier signals and gate drives. Therefore, the overall cost and circuit complexity are greatly reduced. This paper presents modulation methods by a novel reference and multicarrier based PWM schemes for reduced switch cascaded multilevel inverters (RSCMLI). It also compares the performance of the proposed scheme with that of conventional cascaded multilevel inverters (CCMLI). Simulation results from MATLAB/SIMULINK are presented to verify the performance of the nine-level RSCMLI. Finally, a prototype of the nine-level RSCMLI topology is built and tested to show the performance of the inverter through experimental results.

• Smart Structures and Systems
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• 제14권6호
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• pp.1221-1245
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• 2014

Real-time hybrid simulation (RTHS) is a promising cyber-physical technique used in the experimental evaluation of civil infrastructure systems subject to dynamic loading. In RTHS, the response of a structural system is simulated by partitioning it into physical and numerical substructures, and coupling at the interface is achieved by enforcing equilibrium and compatibility in real-time. The choice of partitioning parameters will influence the overall success of the experiment. In addition, due to the dynamics of the transfer system, communication and computation delays, the feedback force signals are dependent on the system state subject to delay. Thus, the transfer system dynamics must be accommodated by appropriate actuator controllers. In light of this, guidelines should be established to facilitate successful RTHS and clearly specify: (i) the minimum requirements of the transfer system control, (ii) the minimum required sampling frequency, and (iii) the most effective ways to stabilize an unstable simulation due to the limitations of the available transfer system. The objective of this paper is to establish a stability switch criterion due to systematic experimental errors. The RTHS stability switch criterion will provide a basis for the partitioning and design of successful RTHS.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 춘계종합학술대회
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• pp.196-200
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• 2003

본 논문에서는 마이크로 컨트롤러를 사용한 다기능 스위치에 대하여 설명한다. 21세기 정보화 시대에 발 맞추어 산업 현장에서는 공장 자동화를 더불어 가정에서는 흠 자동화 시스템이 확산되고 있다. 공장 자동화 및 홈 자동화를 구현하기 위해서 컴퓨터의 사용은 불가피하다. 따라서 사용자와 컴퓨터간 인터페이스 기술과 컴퓨터와 제품간 인터페이스 기술을 요하게 된다. 본 논문의 다기능 스위치는 자동화 시스템 구현에 필요한 인터페이스를 제공해 준다. 또한 마이크로 컨트롤러가 탑재되어 있기 때문에 독립적으로 사용할 수 있다. 따라서 가정에서 간단한 홈 자동화를 구현 할 수 있으며 산업현장에서는 간단한 시퀀스 제어를 이용한 자동화 시스템에 사용될 수 있다. 또한 각종 시스템에 복합적으로 또는 독립적으로 사용이 가능하다.

• 전력전자학회논문지
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• 제17권4호
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• pp.298-305
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• 2012

This paper proposes a soft switching boost converter with an auxiliary resonant circuit. The auxiliary resonant circuit is added to a general boost converter and that is composed of one switch, one diode, one inductor and two capacitors. The resonant network helps the main switch to operate with a zero voltage switching(ZVS) and auxiliary switch also operates under the zero voltage and zero current conditions. The soft switching range is extended by the auxiliary switch and it is possible to control the proposed converter with a pulse width modulation(PWM). The ZVS and ZCS techniques make switching losses decreased and efficiency of the system improved. A theoretical analysis is verified through the simulation and experiment.

• 한국콘텐츠학회논문지
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• 제2권2호
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• pp.73-84
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• 2002

이 논문에서는 큐의 점유량을 줄이고 링크 효율성과 공평성을 제공하며 버퍼관리기법을 사용하는 뛰어난 ERICA 스위치 알고리즘을 제안한다. 제안된 버퍼관리기법은 서로 다른 3개의 하위 임계치, 폭주 통보 임계치, 상위 임계치인 버퍼 임계치를 가지고 있다. 각각의 버퍼 임계치는 상황에 따라 송신원에게 임의 폭주 상태를 다르게 보고한다. 따라서, 송신원은 보다 빠르게 망의 폭주 상태를 알 수 있고 폭주로부터 빨리 회복할 수 있다. 실험 결과들에 따라, 제안된 알고리즘은 기존의 ERICA보다 효율적으로 보여 주고 있다. 특히, 제안된 스위치 알고리즘은 큐의 점유량도 줄이고 공평성 유지를 최적화하여 폭주제안 기법을 제공한다.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1998년도 학술발표대회 논문집 제17권 2호
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• pp.223-226
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• 1998

In the Input Buffer Switch using the intial stage FIFO memory structure, It has pointed the Throughput limitation to the percent of 58.6 due to HOL(Head of Line) blocking in the DBP(Dedicated Buffer with Pointer) method, During that time, To overcome these problems, The prior papers have proposed the complicated Arbitration algorithms and Non-FIFO memory structures. and These showed the improved Throughput. But, Now, To design high speed ATM Switch which need to the tens of Giga bit/s or the tens of Tera bit/s. It has more difficulty in proceeding the priority of majority and the complicated Cell Scheduling, because of the problem in operating the control speed of the ratio of N to scanning each port and scheduling the Cell. In this paper, To overcome these problems, We could show more the improved performance than the existing DBP Window policy to design high speed ATM Switch.

• 한국통신학회논문지
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• 제26권12C호
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• pp.261-267
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• 2001

본 논문은 입력 버퍼와 중앙 중재기 사이에 중재 정보 전달 지연을 갖는 고속 셀/패킷 스위치에 적용된 다중 입력 큐 관리기의 구조 및 Chip 설계 기법을 제안한다. 제안된 다중 입력 큐 관리기의 구조는 wire-speed 셀/패킷 라우팅을 지원하고 입력 버퍼와 중앙 중재기 사이의 중재 정보 전송 지연에 대한 내성을 지원한다. 고속 쉬프터를 사용한 새로운 요청 신호 관리 방법을 사용하여 중재 정보 전송 지연에 대처하며 그로 인한 전체 스위치의 성능 향상을 제공한다. 제안된 다중 입력 큐 관리기는 FPGA Chip을 이용하여 구현되었으며 포트 당 OC-48c 속도를 지원한다. 본 다중 입력 큐 관리기를 이용하여 16$\times$16 스위치 크기와 입력 포트 당 128 셀 공유 버퍼를 가지는 입력 큐 스위치 시스템에서 최대 98.6%의 성능을 가지는 400bps의 스위치 시스템을 개발하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.536-540
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• 2002

In this paper, accelerated life test (ALT) models and procedures for Magnetic Switch (MS) are developed and applied to assure specified reliability of the products at development phase and guarantee the life of the products. Magnetic contactor that functions with over-current relay is called MS. Magnetic contactor closes and opens the motor load with ON/OFF switch of electronic contactor. It is also used for protecting and controlling the load. Magnetic contactor detects the over-current flow in the load with a over-current relay and disconnects the load by opening its control power. In this study, ALT models for MS are developed using the relationship between stresses and life characteristics of products. Using the ALT models, we performed life tests and analyzed the tests results. The proposed ALT models and procedures may be extended and applied to testing similar kinds of products to reduce test times and costs of the tests remarkably. Finally the results of this study will contribute to improving reliability of products and strengthening competitiveness of our products in world markets.

• Journal of Power Electronics
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• 제16권6호
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• pp.2005-2015
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• 2016

A high-step-up DC/DC converter for renewable energy systems is proposed. The proposed structure provides high voltage gain by using a coupled inductor without the need for high duty cycles and high turn ratios. The voltage gain is increased through capacitor-charging techniques. In the proposed converter, the energy of the leakage inductors of the coupled inductor is reused. This feature reduces the stress on the switch. Therefore, a switch with low ON-state resistance can be used in the proposed converter to reduce losses and increase efficiency. The main switch is placed in series with the source. Therefore, the converter can control the energy flow from the source to the load. The operating principle is discussed in detail, and a steady state analysis of the proposed converter is conducted. The performance of the proposed converter is verified by experimental results.