• 전기학회논문지
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• 제67권6호
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• pp.738-744
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• 2018

This paper proposes a low cost hot swap operation circuit of a parallel operation power supply for servers. Hot swap function for server power system is essential in 24 hour operation system such as internet data center, server, factory and etc. Server power supplies used in internet data centers have two or more parallel operations with the hot swap operation. However, the cost of the power supply is high because the controller IC for hot swap operation is very expensive. Therefore, this paper proposes a parallel-operated power supply with a low-cost hot swap controller for servers. The proposed system can operate hot swap function by using discrete devices and reduce the cost by more than 50%. A 1.2kW prototype system is implemented to verify the proposed low cost hot swap controller.

• 전력전자학회논문지
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• 제15권2호
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• pp.96-102
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• 2010

최근 전 세계적인 지구 기후 변화에 따라 에너지를 절약하기 위한 정책이 수립되고 있으며 특히 권고 사양인 CSCI 규제가 점차 강화되고 있어 서버용 전원장치의 효율 조건 역시 높아지고 있다. 이에 따라 서버용 전원 장치의 효율 향상을 얻을 수 있는 기술로서 hold up time extension 기술이 많은 주목을 받아왔다. Hold up time 보상기술은 서버용 전원 장치가 가지는 hold up time 이라는 특징으로 인하여 발생할 수 있는 손실을 추가적인 기술을 통하여 보상함으로서 효율을 높일 수 있는 방법으로 그동안 많은 연구가 이루어져 왔다. 본고에서는 고효율 고밀도 서버용 전원장치를 위한 hold up time 보상회로에 대하여 알아보고자 한다.

• 한국컴퓨터정보학회논문지
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• 제21권6호
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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.

• ETRI Journal
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• 제32권6호
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• pp.940-949
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• 2010

Rack-level DC power supply is the optimal technology for providing DC power to a volume server without any power infrastructure changes in an existing AC data center. In this paper, we propose a smartly controllable and monitorable DC rack power system. The proposed system improves power efficiency by changing the power distribution architecture of a conventional method in the rack. We developed an optimal power control method in multipower modules to provide high efficiency at low loads. In addition, the proposed system provides real-time web monitoring of the rack power and environment around a rack. In our experiments, the proposed system improved the power efficiency by over 10% compared to an AC power system providing N+1 redundant power and power monitoring.

• Journal of Power Electronics
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• 제12권1호
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• pp.157-163
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• 2012

Internet Data Centers (IDCs), which are essential facilities in the modern IT industry, typically have scores of MW of concentrated electric loads. The provision of an Uninterruptible Power Supply (UPS) is necessary for the power feed system of IDCs owing to the need for stable power. Thus, conventional IDC AC power feed systems have three cascaded power conversion stages, (AC-DC), (DC-AC), and (AC-DC), resulting in a very low conversion efficiency. In comparison, DC power feed systems require only a single power conversion stage (AC-DC) to supply AC main power to DC server loads, resulting in comparatively high conversion efficiency and reliability [4-11]. This paper compares the efficiencies of a 220V AC power feed system with those of a 300V DC power feed system under equal load conditions, as established by the Mok-Dong IDC of Korea Telecom Co. Ltd. (KT). Experimental results show that the total operation efficiency of the 300V DC power feed system is approximately 15% higher than that of the 220V AC power feed system.

• Journal of Power Electronics
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• 제16권1호
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• pp.121-132
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• 2016

In this paper, high-efficiency design methodology of a zero-voltage-switching full-bridge (ZVS-FB) pulse width modulation (PWM) converter for server-computer power supply is discussed based on self-driven synchronous rectifier (SR) performance. The design approach focuses on rectifier conduction loss on the secondary side because of high output current application. Various-number parallel-connected SRs are evaluated to reduce high conduction loss. For this approach, the reliability of gate control signals produced from a self-driver is analyzed in detail to determine whether the converter achieves high efficiency. A laboratory prototype that operates at 80 kHz and rated 1 kW/12 V is built for various-number parallel combination of SRs to verify the proposed theoretical analysis and evaluations. Measurement results show that the best efficiency of the converter is 95.16%.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2012년도 한국컴퓨터종합학술대회논문집 Vol.39 No.1(A)
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
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• pp.13-15
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• 1993

Because of the increase of complexity of power system problems it becomes nessesery to design the integrated system that can deal with system data with easy. Open Client/server system with RDBM is a good solution for KECO system.

• 전력전자학회논문지
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• 제17권2호
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• pp.150-157
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• 2012

This paper presents CAN-based parallel-operation and load-sharing techniques for the communication server power supply. With the load information obtained through CAN communication, each modules performs its current control independently and the power unbalance caused by impedance differences of converter modules can be reduced. In conventional method, slave modules are controlled by master module. On the other hand, the proposed load share algorithm uses the Multi-Master method. Therefore, accurate load sharing can be accomplished by the reference structure of each module's average current. Each converter has two stages and it is separated into PFC, which is responsible for harmonic regulation, and LLC resonant converter, which controls output voltage. To verified the performance of the proposed method, two 2KW prototypes has been implemented and experimented.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.382-384
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• 2008

Hold-up time is a special requirement for the front end DC/DC converter in a server power supply. It forces the converter with the variable switching frequency to operate in a wide switching frequency range, which makes the regulation difficult and reduces the power density. In this paper a novel frequency controlled half bridge converter with the hold-up time extension circuit is proposed. During the hold-up time, the auxiliary switches are turned on, thus the resonant inductance is reduced and the voltage conversion ratio is increased. Therefore, the output capacitor of the power factor correction (PFC) circuit can be decreased, and the converter can have high power density. The proposed converter is verified by experimental results from a prototype with 700W, 400V input, and 12V output.