• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.288-290
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• 2006

An efficiency improving method for Uninterruptible Power Supply System(UPS) was developed by using OP-AMP based application circuits such as voltage detection device, current detection device and static switch control device. The efficiency improving algorithm was made by mixing the operating concepts of On-Line type UPS with the operating concepts of Off-Line type UPS. The UPS' inverter does not work if the UPS' output load current is not higher than the low load operating current which is about 0-30(%) of the UPS' output load capacity. The low load operating current is adjustable within the half of the UPS' output load capacity. If the UPS' output load current is rising over than the low load operating current, the UPS' inverter starts working and the inverter output power feeds to the loads of UPS. If UPS' input power breaks out while UPS' inverter does not operate because the load current is low, the inverter starts working within 4(ms) with excessive output voltage which is ${\pm}$8(%) of normal UPS' output voltage. Like these. UPS can continuously feeds power to it's load device and reduce power consumptions.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.367-371
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• 2007

Large capacity UPS and emergency generators are being installed and operated at the specific target of important electric facilities that need uninterruptible power supply by the method of countermeasure against power failure for the less reliable incoming power method. Recently, CTTS (Closed Transition Transfer Switch) is being used as uninterruptible power transfer switch at the Common sources of electricity, generator and multiple generators. In this paper, construction plans for uninterruptible power supply system has been suggested in which CTTS has been applied to the secondary of incoming power generator for reliable common dual system method. By briefing the construction of incoming power facilities, large capacity UPS, emergency generator installation space and investment saving effects can be achieved.

• Proceedings of the KIPE Conference
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• 2003.11a
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• pp.202-205
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• 2003

Recently, UPS(Uninterruptible Power Supply) have been largely used to improve power souse quality as well as to protect critical loads such as computer, industrial system, medical equipment, etc, against power outage by providing clean and uninterrupted power under power supply disturbance or interruptions. But UPS is bulky because used battery. So, UPS size issue have received attention in the power electronics industry. Therefore, this paper proposed a implementation of inside of the computer power supply with UPS by the one-chip microprocessor to minimize UPS size. To verify the proposed power supply, the detail simulation and experiment results indicate that high-frequency switching and operation UPS can be achieved.

• Journal of the Korea Society of Computer and Information
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• v.21 no.6
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• pp.1-7
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• 2016

An uninterruptible power supply (UPS) allows small companies and domestic users to cope with power outages; but existing designs lack flexibility of control and require expensive battery maintenance, with a cost proportional to the outage compensation time. We combine a compact synchronous generator with a battery, with 10% of the capacity that would otherwise be required, to obtain a UPS with reduced maintenance costs for the same performance. Any UPS must respond immediately to a power loss, and our uninterruptible generator supply (UGS) is therefore built around real-time scheduling of its internal operations; this also makes it suitable for integration into the industrial gateway. The UGS is based on a real-time operating system, with an integrated wireless module providing connectivity to a web server, for monitoring and management, which can be performed remotely on a mobile device.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2613-2615
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• 1999

In the paper, a new single phase uninterruptible power supply(UPS) scheme is proposed. A conventional UPS can supply power to the load continuously. However, it may generate input current harmonics and the input power factor is very poor. This paper proposes a phase control converter for single phase UPS. It mainly consists of a minimized structure of power converter which is capable of providing a specified constant output voltage, phase controlled battery charger. The proposed scheme is validated with a computer simulation.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.299-301
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• 2007

본 논문은 무정전 전원공급장치(UPS : Uninterruptible Power Supply System)에서 출력이 중단되는 상황을 최종 출력단에서 감지하여, 첫째 고장 영향의 확산을 차단하고, 둘째 부하에 무정전의 전원공급을 실시할 수 있도록 하는 고속절환장치에 관한 것이다. 본 시스템은 기존 UPS 시스템이 가지고 있는 출력전원을 검출하여 기준전압 범위에서 벗어나면 절체 시키는 일반적인 방식이 아니라, 별도의 시스템을 UPS와는 독립적으로 구성하여 UPS 내부 사고시 고장이 부하와 계통상에도 영향을 주는 현상을 차단하기 위하여 절체 시점에서의 이상적인 접점 상태를 고려하고, UPS의 모든 제어시스템이 불가능한 시점에서도 부하의 연속성을 보장할 수 있도록 구성한 독립제어 고속절환장치 개발에 관한 논문이다.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.4
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• pp.341-349
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• 2004

A parallel operation of Uninterruptible Power Supply(UPS) systems is used to increase power capacity of the system or to secure higher reliability at critical loads. In the conventional parallel operation, the load-sharing control to maintain the current balance is the most important, since the load-sharing is very sensitive to discord between components of each module, amplitude/phase difference, line impedance, output LC filter, and so on. To solve these problems various control algorithms are researching. However, these methods cannot apply to the different ratings of UPS. In the case, master and slave control algorithm for parallel operation is adequate. However, if the UPS ratings are different, the value of passive filters L, C is different, and it affects the sharing of current. This paper presents general problems of conventional parallel operation systems, and control strategy for parallel operation with different ratings. The validity of the proposed control strategy is investigated through simulation and experiment in the parallel operation system with two 3-phase UPS systems.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.6
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• pp.191-196
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• 2019

In the case of urban railway facilities, the power supply should be maintained for the safe movement of passengers in communication facilities, disaster prevention facilities and boarding area security because of the confusion when power supply is cut off due to the nature of public transportation. In addition, considering that the number of trains is running on the urban railway line, it is necessary to operate at least 30 minutes for the bus stop and at least 1 hour for the communication and disaster prevention facilities. Therefore, it is essential to supply emergency power source to maintain stable operation of induction lamp and smoke exhaust system because main power is cut off in order to prevent further spread due to fire in case of the history of urban railway section or vehicle fires. Recently, UPS(Uninterruptible Power Supply) function to prevent power outage in emergency, emergency power generation combined with ESS function which saves electricity at nighttime price time, A hybrid power storage system with a UPS function.

• Proceedings of the KIEE Conference
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• 2005.10a
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• pp.132-135
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• 2005

A design for the input filter and the output filter of a single-phase uninterruptible power supply (UPS) system is proposed. A filter design example is presented. And also, this dissertation describes a reduction of the DC voltage ripple of a single-phase UPS. The input power of proposed UPS fluctuates with twice frequency of the utility source, which causes DC voltage fluctuation. The reduction of the DC voltage fluctuation requires a large DC link capacitor. The proposed method uses a LC series resonant filter paralleled with a conventional smoothing capacitor. The effectiveness of the proposed method was confirmed by simulation results.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.4
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• pp.302-311
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• 2016

This paper proposes a hybrid ESS that integrates an energy storage system (ESS) with an uninterruptible power supply (UPS). The hybrid ESS has a demand management and emergency power supply function while increasing the battery utilization of the UPS, which has just been used in a power failure. In addition to the critical load, the proposed system augments the capacity of emergency generation using an additional load, which has voltage and frequency-dependent characteristics to the grid side. The control algorithm of the AC-DC converter and bidirectional DC-DC converter is proposed for demand management and emergency power supply. Furthermore, seamless and autonomous transfer methods to alleviate the transient during mode transfer are proposed. To validate the proposed control scheme, experimental results from a 5 kW prototype are provided.