• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.986-989
• /
• 2004

The concept and results of a simple constant switching frequency delta modulation scheme suitable for DC-AC power conversion in uninterruptable power supply (UPS) applications are presented. Unlike the traditional delta modulation scheme, the scheme has a well defined harmonic spectrum, resulting in a simple filter design and reduced radio interference.

• Proceedings of the KIPE Conference
• /
• 2015.11a
• /
• pp.149-150
• /
• 2015

This paper presents narrowband voltage controller for large capacity UPS system with low switching frequency. The proposed controller is repetitive controller applicable to low sampling. The controller reduces the control error for nonlinear load and improve efficiency. The proposed controller is verified through the experiment using 40kW UPS inverter.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.12 no.4
• /
• pp.100-105
• /
• 1998

This paper proposes a new control strategy of bidirectional uninterruptible power supply (UPS) with the performance of active power filter which compensates the harmonics and reactive power. With only one power stage, it is working simultaneously as the AC/DC rectifier/battery charger and DC/AC inverter to the operation of battery charging or back-up power supplying. Therefore the operation of the proposed system can be divided into the modes, such as the active power filter mode and the battery back-up power mode. And a novel closed-loop control strategy is used to calculate the reference current. The performance of the proposed 5[kVA] system is verified by the simulation and experimental results.

• Proceedings of the KIPE Conference
• /
• 2014.07a
• /
• pp.443-444
• /
• 2014

Using the ESS(Energy Storage System) as a UPS(Uninterruptible Power Supply) is being studied recently. When the system is operating at UPS mode in integrated ESS and UPS system, the grid supplying power is disconnected and power from PV generation and battery are supplying to load. Operating in UPS mode, when PV generation power is diminished by partial or total clouded situation, DC-link voltage fluctuates. The fluctuation of DC-link voltage influences the load and system as sensitive loads may malfunction. This paper suggests the DC-link ripple voltage compensation algorithm in bi-directional converter. The algorithm stabilize the DC-link and load voltage.

• Proceedings of the KIPE Conference
• /
• 2015.11a
• /
• pp.197-198
• /
• 2015

본 논문은 에너지저장(ESS : Energy Storage System) 기능을 갖는 500kVA급 3-Level 하이브리드 무정전전원장치(UPS : Uninterruptible Power Supply)에 관한 것으로 평상시 무정전 전원장치의 기능을 수행하다 전력 부족시 또는 첨두부하시 에너지저장 기능을 제공하는 기술에 대한 내용이다. 실험을 통하여 제안한 시스템의 우수성을 검증한다.

• Proceedings of the KIEE Conference
• /
• 1995.07a
• /
• pp.206-208
• /
• 1995

Recently according to the increasing critical loads such as communication and life support systems stable power supplying becomes more and more important. Therefore it is indespensable to stabilize power source using these instruments - AVR(Automatic Voltage Regulator) or UPS(Uninterrutible Power Supply). This paper deals with ON-LNE UPS which is composed of PWM converter for AC-DC conversion. Using a PWM converter have advantages of low current harmonics and high power factor. In this paper ON-LNE UPS using PWM converter is proposed and its characteristics are investigated.

• Proceedings of the KIPE Conference
• /
• 1999.07a
• /
• pp.448-451
• /
• 1999

This paper describes controller development for a dynamic voltage compensator using a shunt diode converter and series inverter. The control system was designed using 1/4 period integrator and vector relationship between the supply voltage and load voltage. A simulation model and scaled hardware model were developed for analyzing performance of the controller and the whole system. Both results confirm that the dynamic compensator can restore the load voltage under the fault of the distribution system.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.7 no.6
• /
• pp.1086-1091
• /
• 2006

In this paper an advanced PLL strategy suitable to UPS, compared with conventional PLL strategy using the positive sequence component extracted from source voltages, is suggested. Frequency limiter and anti-windup are added to conventional PI controller in suggested PLL strategy. Basic operational principle of suggested PLL is same as that of conventional PLL, but the difference between two strategies is that the suggested PLL can limit the change of frequency in constant range because of inclusion of frequency limiter. Compute. simulation was carried fer the DVR(dynamic voltage restorer) compensating voltage to examine the difference between conventional PLL strategy and the suggested PLL strategy limiting frequency. And the results clearly demonstrate the effectiveness of the suggested PLL strategy for UPS.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.17 no.4
• /
• pp.353-358
• /
• 2012

In this paper, three-phase power equalizing system (PES) with UPS function is proposed. This system is based on NiMH battery with battery management system. The power conversion circuit is composed with the three-phase converter/inverter, the bi-directional converter, and the thyristor switches. The three-phase converter/inverter provides the power to the grid or get the power from the grid. Also, it operates as a UPS. The bi-directional converter charges or discharges the battery. The thyristor switches are used for connecting/disconnecting with the grid and the load. A 15 kW prototype is implemented for the verifying the performance of the proposed system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2006.05a
• /
• pp.685-688
• /
• 2006

A single-phase uninterruptible power supply system suitable for a SMES unit is proposed to achieve a simple circuit configuration and higher system reliability. It reduces the number of switching devices by applying a common-arm scheme. Operational principles to normal, stored-energy, and bypass mode are discussed in detail. Eliminating some of the switches or substituting passive components for active switches generally increases the sophistication and reduces degree of freedom in control strategy. However, the high-performance digital controller ran execute the complicated control task with no additional cost. The validity of the proposed UPS system will be verified by a computer-aided simulation.