• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.41-44
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• 1999

The main purpose of the UPS is to supply independent and stable power to connected equipment. In installing and operating the UPS system, songle module, three phase UPS in more benefit than multi module, songle phase UPS in the point of volume and cost. However, when supplying Rectifier with output power form three phase UPS, by connecting auto-transformer, occurred harmonic and ripple current makes output filter damaged and leads to nonlinear current coasted by unbalance load. Therefor, in this paper the aim of concentring compound-wound transformer and harmonic filter is supplying liner current by reducing harmonic and ripple current and improving unbalance in voltage and distortion in current wave.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.445-447
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• 1997

In this paper a remote monitoring and control system using Modem for UPS (Uninterruptible Power Supply) is proposed. The conventional remote monitoring system for UPS is used to local remote monitoring system by RS232 or RS485 communication code. But recently. the system is changed to wide remote monitoring and control system using Modem for quick analysis of errors, correction of errors, report of errors and other user-friendly functions. In this study, we designed and develope system which is able to control UPS an monitor errors, statuses, actual values transmitted from UPSs of each site.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06a
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• pp.236-238
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• 2012

본 논문은 저전력 데이터센터에 사용되는 DC 서버를 위한 고효율 DC UPS 결합형 전원분배장치의 구현과 설계에 관한 내용이다. 본 논문이 제안한 노드 준위 UPS 결합형 전원분배장치의 전력효율은 96%에 이르며 저전력 볼륨 서버의 전원공급장치(PSU)와 UPS를 대체할 수 있는 기술이다.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.260-265
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• 1999

This paper describes a novel control method of a three-phase PWM inverter for uninterruptible power supply(UPS) applications. To obtain the fast dynamics and excellent harmonic characteristics, a new state feedback control technique is proposed. The proposed control consists of the inner-loop current and outer-loop voltage controllers with a load current estimator to reduce the effects of the load variations and nonlinearity. In order to verify the effectiveness of the proposed control, the simulation is carried out for various load condition.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.67-68
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• 2015

본 논문에서는 멀티모듈 단상 UPS(Uninterruptible Power Supply) 시스템의 예측 제어기법을 제안한다. 제안한 예측 제어기법은 단상 UPS의 수학적 모델링을 통해 설계되었으며, 전류 예측제어를 통해 모드 절환 시 동특성을 향상시켰다. 제안하는 예측 제어기법은 PSIM 시뮬레이션을 통하여 검증하였다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.1
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• pp.69-77
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• 1998

The uninterruptible power supply (UPS) has become an integral part of modern computer and communication system to assure a continued and stable operation by providing an uninterruptible power to vital equipments. Various control methods have come to the fore in recent times with the advent of high frequency switching technologies. This paper describes the DSP control method for three phase UPS inverter which guarantees the sinusoidal output voltage under nonlinear load conditions. The proposed control scheme is verified by simulation and experiment.riment.

• Journal of Power Electronics
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• v.5 no.2
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• pp.160-165
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• 2005

In a parallel operation of UPS, there are two types of circulating currents between UPS. One is the low order circulating current with a fundamental frequency caused by the amplitude and phase differences of UPS output voltages, and the other is the harmonic circulating current with PWM switching frequency caused by non-synchronized PWM waveforms among UPS. The elimination of the low order circulating current is essential for optimal load sharing in parallel operations of UPS, which can be accomplished by the phase and magnitude control at each UPS. The harmonic circulating current may cause troubles and deteriorate in performance of the controller for optimal load sharing in parallel operation of UPS. This paper presents a PWM synchronizing method to eliminate the harmonic circulation current in parallel operation of UPS. The effectiveness of the proposed scheme has been investigated and verified through experiments by a 50kVA UPS.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.1
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• pp.19-28
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• 2022

In this study, three types of combined isolator consisting of High Damping Rubber Bearing (HDRB) and wire isolator were developed for Uninterruptible Power Supply system (UPS). The dynamic characteristics of the combined isolator were investigated through one-axis shaking table test. The input acceleration were generated in accordance with ICC-ES AC156 code. Scale factors of the input acceleration were designed to be 0.5-2 times the required response spectrum defined in ICC-ES AC156. Based on the test results, damage and dynamic characteristics of the UPS were investigated: including natural frequency, damping ratio, acceleration time history response, dynamic amplification factor and relative displacement. Based on that, it was found that the combined isolator developed in this study could improve the seismic behavior of the UPS, in particular, the response acceleration.

• Journal of Power Electronics
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• v.5 no.4
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• pp.312-318
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• 2005

This paper presents a compensator for reduction of the reactive lateral current in multiple autonomously controlled uninterruptible power supplies (UPS) connected in parallel. This compensator acts directly on the control equation for voltage amplitude and it provides an improved current distribution especially in the case of parallel connection of UPSs with different output power ratings. Observations show that the original control equation for output voltage amplitude is efficient for voltage regulation but it causes great variation of voltage levels. A compensator with the same structure is added to counterbalance the variation caused by the original control equation. Simulations show promising results with the employment of the proposed compensator. Our simulations are confirmed by experimental results using three UPSs with different output ratings and voltage limiters ($1\%$) connected in parallel under various conditions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.6
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• pp.1072-1077
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• 2006

In this paper a novel 3-phase line interactive UPS(Uninterruptible Power Supply) system with parallel-series active power-line conditioning capability using AC line reactor and two four-leg PWM VSCs(Voltage Source Converters) is proposed. And the strategy of voltage control in proposed UPS system is explained. The objective of voltage control in parallel(shunt) and series PWM VSC of proposed UPS system is to guarantee satisfactory characteristics in steady state and transient state.