• 전력전자학회:학술대회논문집
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• 전력전자학회 2009년도 정기총회 및 추계학술대회 논문집
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• pp.287-289
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• 2009

This paper deals with a parallel processing uninterruptible power supply (UPS) for sudden voltage fluctuation in computer applications to integrate power quality improvement, load voltage stabilization and UPS. To reduce the complexity, cost and number of power conversions, which results in higher efficiency, only one voltage-controlled voltage source inverter (VCVSI) is used. The system provides sinusoidal voltage at the fundamental value of 220V/60Hz for the load during abnormal utility power conditions or grid failure. Also, the system can be operated to mitigate the harmonic current and voltage demand from nonlinear loads and provide voltage stabilization for loads when sudden voltage fluctuation occur, such as sag and swell. System operation simulation demonstrates that the system protects against outages caused by abnormal utility power conditions and sudden voltage fluctuations and changes.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.1055-1059
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• 1992

Instantaneous Voltage Control of inverter for uninterruptible power supply(UPS) is presented. In order to improve the transient response, the authors propose a control scheme based on a double regulation loop with sinusoidal hysteresis band. And also, using 8097 single chip microprocessor, software synchronization and static switch control scheme is impremented with minimal hard ware structure.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 전문대학교육위원 P
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• pp.56-60
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• 1999

This paper presents the high performance real time control system of PWM inverter for uninterruptible power supply(UPS). This system is based on a digital control scheme which calculates the pulse widths of the inverter switches for the next sampling time in digital signal processor(DSP). A PI compensator is used to eliminate the voltage error caused by the difference between the actual values of LC filter and those designed. Double regulation loops which are the inner current loop and the outer voltage loop are used to make the transient response time reduce in load disturbance and nonlinear load. This method makes it possible to obtain better response in comparison to conventional digital control system. The proposed scheme provides good performance such as stable operation, low THD of the output voltage, and good dynamic response for load variations and nonlinear load.

• 설비공학논문집
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• 제19권4호
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• pp.328-332
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• 2007

A superconducting magnetic energy storage (SMES) system has shorter response time and longer life time, and is more economical, and environment-friendly than other uninterruptible power supply (UPS). A conduction cooling system is well answer for the high temperature superconductor (HTS) SMES system. Because the conduction cooling system is simple, light and small structure. The purpose of this paper is to design and verify the effective conduction cooling system for the HTS SMES system. The analysis of heat loads in cryostat is performed. Thermal shield heat loads, temperatures of HTS coil surface and conduction Cu plate are estimated and measured.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 A
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• pp.82-84
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• 2000

This paper deals with a evaluation algorithm of interruption cost in distribution systems in the case where Dispersed Storage and Generation (DSG) systems are interconnected with the distribution systems. If DSG systems are operated as the function of the load levelling in distribution systems at the normal conditions and as the uninterruptible power supply in fault areas at the emergency conditions, the reliability improvement of the distribution systems can be expected. In other words, the benefit can be represented by the cost avoiding interruption according to the operation of DSG systems when a fault is occurred. Therefore, this paper presents the evaluation algorithm for interruption cost in order to evaluate the benefit for the uninterruptible power supply of DSG systems in a quantitative manner.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 F
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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.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.813-817
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• 1998

This paper proposes a new control strategy of bidirectional uninterruptible power supply(UPS) with the performance of active power filter which compensate the harmonics and reactive power. To improve the transient response for the effective compensation in active power filter mode. It is considered that a simple and precise calculation method of the compensation reference current for the harmonics and reactive power compensation. So a novel closed-loop control strategy is used to calculate the reference current. The system model and control algorithm are described and the system performance is verified by the simulation and experimental results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.830-835
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• 1998

This paper describes a new digital control method of 3-phase PWM inverter with LC filter for uninterruptible power supply(UPS). The overall control system is based on the dead beat control, which has the minor loop of current control within the voltage control major loop. In this paper, the full-order disturbance observer is proposed to compensate the disturbances generated due to a sudden change of load currents. The proposed disturbance observer is composed of dead beat observer which estimates state values within a finite time, and cancels the disturbances by adding feedforward compensation loop in the control system. In addition, on order to remove a defect of oscillation generated in output of conventional dead beat controller, a modified dead beat algorithm is proposed in this paper.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2013년도 전력전자학술대회 논문집
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• pp.5-6
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• 2013

This paper proposes the PFC converter design for Uninterruptible Power Supply(UPS), including Battery discharger. Battery discharger supplies power to the inverter, when accidents occur, such as power failure, blackout, overload. To verify the validity of proposed the PFC converter design including battery discharger, simulations are carried out.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 전문대학교육위원
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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.