• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.312-317
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• 1996

This paper compares the output voltage control strategies of three-phase PWM inverter for uninterruptible power supply. The feedforward control, feedforward/feedback control, and decoupled feedback control in both the synchronous reference frame and the stationary reference frame are examined. In particular, it is shown that the response of the decoupled feedback controller in the synchronous reference frame can be improved by pole-zero cancellation method. It is also shown that the pole-zero cancellation method reduces to the deadbeat control, when it is implemented with digital controller.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 F
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• pp.2587-2589
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• 1999

In this paper, we propose a new control scheme for a PWM inverter using digital control. Digital control has various advantages in comparison with conventional analogue control. It can achieve high frequency switching of inverter and can be little influenced for temperature variations and aging of devices. This digitally-controlled PWM inverter is implemented using a Digital Signal Processor(DSPTMS320F240). The simulation results are given to verify the DSP based PWM inverter design and implementation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 A
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• pp.394-396
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• 1995

This paper present fuzzy control technique for the control of output voltage and improvement of UPS wave forms. General UPS has the harmonics in carrier because of output of PWM signal using analog circuit. Output voltage is controlled by selecting PWM data to improve these problems, PWM signal discreted is written on ROM and analog circuit is removed at the system and output voltage is controlled by selecting PWM data by fuzzy controller.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.381-383
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• 1999

In this paper a remote monitoring and control system using SNMP(Simple Network Management Protocol) for UPS (Uninterruptible Power Supply) systems is proposed. The local remote system by RS-232 or RS-485 communication code or the wide remote system by modems is used for conventional remote monitoring & control system for UPSs. But recently because of communication cost and long distance the system is changed to remote control systems through internet and information communication network. And serial communication method by RS-232 or RS-485 is used between agent and UPSs. In this study. we designed and developed the system which is able to control UPSs and to monitor errors. statuses and actual values transmitted from UPS through internet.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(1)
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• pp.77-81
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• 2004

In this paper a novel line interactive UPS (Uninterruptible Power Supply) using the two 4-leg VSCs and AC line reactor is proposed. The 4-leg Voltage Source Converter(VSC) can use the DC link voltage effectively by the 3-D SVPWM method. Hence the DC battery voltage can be reduced by $15\%$ in comparison to that of the conventional line-interactive UPS system. One VSC is in parallel with the AC line reactor of the power source side, and the other is in series with the load. The parallel 4-leg voltage source inverter controls three-phase line voltage independently in order to control the line reactor current indirectly. It eliminates the neutral line current and the active ripple power of the source side using the pqr theory so that unity power factor and the sinusoidal source current can be achieved even though both the source and the load voltages have zero sequence components. The series 4-leg voltage source inverter compensates the line voltage and allows the load voltage to be balanced and harmonic-free. Both of parallel and series 4-leg voltage source inverters always act as independently controllable voltage sources, so that three-phase output voltage shows a seamless transition to the backup mode. The feasibility of the proposed UPS system has been investigated and verified through computer simulation results.

• 조명전기설비학회논문지
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• 제18권5호
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• pp.140-145
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• 2004

본 논문은 사이리스터 또는 GTO사이리스터를 이용한 변형된 DC리액터형 고온초전도 전류제한기의 부하단 사고시 사고전류 제한동작 뿐아니라 전원단 사고로 인해 부하로의 전력공급이 중단되었을 경우, 평상시 초전도코일에 저장된 에너지를 이용하여 부하에 연속적인 전력을 공급할 수 있는 기능을 수행할 수 있음을 분석하였다. 시뮬레이션 결과는 이론적인 분석과 일치함을 나타내었다.

• Journal of Electrical Engineering and Technology
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• 제9권3호
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• pp.812-819
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• 2014

The proposed technical work attempts to compare the two key technologies of power distribution, i.e. direct current (DC) and alternating current (AC) in a fiscal manner. The DC versus AC debate has been around since the earliest days of electric power. Here, at least four types of a low voltage DC (LVDC) distribution are examined as an alternative to the existing medium voltage AC (MVAC) distribution with an economic assessment technique for a project investment. Besides, the sensitivity analysis will be incorporated in the overall economic analysis model to cover uncertainties of the input data. A detailed feasibility study indicates that many of the common benefits claimed for an LVDC distribution will continue to grow more profoundly as it is foreseen to arise with the increased integration of renewable energy sources and the proliferation of energy storage associated with the enhanced utilization of uninterruptible power supply (UPS) systems.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1413-1415
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• 2005

In paper, propose new partial resonance ZCS PWM controlled High frequency insulating Full-bridge DC/DC converter not using exciting current of high frequency transformer. It is compared with the existing principles in characteristics. It also realizes a widely stabilized ZVS operating using new On-Off control method at synchronized power rectification MOSFET of high frequency insulating transformer secondary. Finally, it is brought over 97[%] measurement -efficiency by proposed DC-DC converter. It is proved effectiveness of new methods using DC UPS PWM rectifier as switching power.

• 한국초전도ㆍ저온공학회논문지
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• 제10권1호
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• pp.62-66
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• 2008

The characteristic of the superconducting magnetic energy storage(SMES) system is faster response, longer life time, more economical, and environment friendly than other uninterruptible power supply(UPS) using battery. So, the SMES system can be used to develop methods for improving power quality where a short interruption of power could lead to a long and costly shutdown. Recently, cryogen free SMES has developed using BSCCO(Bismuth Strontium Calcium Copper Oxide) wire. We fabricated and tested the conduction cooling system for the 600 kJ class HTS SMES. The experiment was accomplished for the simulation coils. The simulation coils were made of aluminium, it is equivalent to thermal mass of 600 kJ HTS SMES coil. The coil is cooled with two GM coolers through the copper conduction bar. In this paper, we report that the test results of cool-down and heat loads characteristics of the simulation coils. The developed conduction cooling system adapted to 600 kJ HTS SMES system and cope with the unexpected sudden heat impact, too.

• 한국정보통신학회논문지
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• 제9권1호
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• pp.146-151
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• 2005

본 논문에서는 단상 무정전 전원공급 장치의 성능시험을 위한 새로운 방식의 전압변동 발생기를 제안하였다. 제안한 방식의 컨버터는 정상적으로 공급되는 상용전원으로부터 순시접압강하, 순시전압상승, 순간정전 등을 발생시켜서 시험하고자 하는 단상 무정전 정원공급 장체에 인가할 수 있다. 제안한 발생기의 구조는 매우 간단하며 경제적이고 전압변동을 발생시키기 위한 제어방식 또한 간단하여 신뢰도와 효율이 높은 장점을 갖는다. 제안한 방식에 대한 회로분석과 동작원리를 기술하였으며 제안한 방식의 타당성을 컴퓨터 시뮬레이션과 실험을 통하여 확인하였다.