• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.10
• /
• pp.1672-1681
• /
• 2016

This paper proposes a wireless parallel operation method of three-phase modular UPS inverter using resistive droop control. Furthermore, it applies a virtual resistor to droop control so that the output impedance of UPS inverter gets closer to resistive. It makes resistive droop control effective. The simulation using PSIM was performed in order to verify the validity of proposed algorithm. After consisting two-parallel system with three-phase modular UPS inverter, the experiment according to resistive load was conducted. It demonstrated the performance of current sharing and power sharing.

• Journal of Industrial Technology
• /
• v.31 no.B
• /
• pp.75-79
• /
• 2011

In this paper a new PFC Controller for 3-Phase Modular UPS(Uninterruptible Power Supplies) is proposed. The PFC circuit for 3-Phase Modular UPS is implemented using three 1-phase 3-level boost PFC circuits. To control DC output voltage, single voltage controller considering imbalance of two capacitor voltages and to regulate AC input current three independent current controllers are used in proposed PFC controller. By the proposed method, without additional hardware, THD(Total Harmonic Distortion) of input currents can be readily limited below 5% which is the harmonic current requirements by IEEE std. 519. Its validity is verified by simulations and experiments.

• Proceedings of the KIPE Conference
• /
• 2010.11a
• /
• pp.44-45
• /
• 2010

In this paper a new PFC Controller for 3-Phase Modular UPS is proposed. The PFC circuit for 3-Phase Modular UPS is implemented using three 1-phase 3-level boost PFC circuits. To control DC output voltage and AC input current, single voltage controller considering imbalance of two capacitor voltages and three independent current controllers are used in proposed PFC controller.

• Journal of Industrial Technology
• /
• v.32 no.A
• /
• pp.39-45
• /
• 2012

In this paper the digital control scheme of interleaved PFC for 3-phase modular UPS is presented. The interleaved PFC is composed of two identical PFC connected in parallel and each PFC is controlled by the interleaved switching signals which have the same switching frequency and the $180^{\circ}$ phase difference. As a consequence of the interleaving operation, the Interleaved PFC exhibits both lower current ripple at the input side and lower voltage ripple at the outside. Therefore, the switching and conduction losses as well as EMI levels can be significantly decreased. Simulation and experimental results verify the usefulness of the interleaved PFC.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.6 no.6
• /
• pp.489-497
• /
• 2001

The proposed dobule phase locked loop and active multiple interphase reactor are used to eliminate the circular current and the voltage ripples caused by the system parameter unbalance of parallel connected UPSs. In this paper, digital controller for the dobule PLL and active interphase reactor is implemented with ADSP21061 as an aspect of functional convenience.

• Proceedings of the KIPE Conference
• /
• 2016.07a
• /
• pp.479-480
• /
• 2016

This paper introduces a master and slave control algorithm for parallel operation of UPS system. If each module of UPS system control the output voltage and filter inductor current in parallel operation, it occur unbalanced output power each module. To operate UPS system parallel, it need a algorithm that control output power of modules. A master and slave control algorithm is helpful to balance output power of modules by controlling output current. The effect of a master and slave control algorithm is proved by simulations.

• Proceedings of the KIPE Conference
• /
• 2017.07a
• /
• pp.423-424
• /
• 2017

본 논문은 에너지저장(ESS : Energy Storage System) 기능을 갖는 1,200kVA급 모듈형 하이브리드 무정전전원장치(UPS : Uninterruptible Power Supply)에 관한 것이다. 제안한 모듈형 하이브리드 UPS는 평상시에는 무정전전원장치의 기능을 수행하면서 잉여 전력을 미리 배터리에 저장하였다가 첨두부하시 또는 전력 부족시 에너지저장 기능을 하여 전력을 조절할 수 있다.

• Proceedings of the KIPE Conference
• /
• 2015.11a
• /
• pp.201-202
• /
• 2015

본 논문은 단위 용량이 33kVA인 모듈을 6개 병렬운전 하여 최대 200kVA로 동작하는 모듈형 무정전전원장치(UPS : Uninterruptible Power Supply) 개발에 관한 것이다. 모듈형 무정전전원장치는 각 모듈이 병렬로 동작하기 때문에 특정 모듈이 고장 나더라도 나머지 모듈이 정상적으로 동작하기 때문에 신뢰성이 높고 모듈이 장애가 발생한 경우 모듈 교체를 통하여 장애를 해결할 수 있으므로 유지 및 보수가 용이하다. 제안한 시스템의 유용성을 실험을 통하여 검증한다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.18 no.6
• /
• pp.205-212
• /
• 2004

In this paper the design of a 1-[KVA] fuel cell powered line-interactive UPS system employing modular (fuel cell & DC/DC converter) blocks is proposed. The proposed system employs the two fuel cell modules along with suitable DC/DC converters and these modules share the DC-Link of the DC/AC inverter. A supercapacitor module is also employed to compensate for the instantaneous power fluctuations and to overcome the slow dynamics of the fuel processor. The energy stored in the supercapacitor can also be utilized to handle the overload conditions for a short time period. Due to the absence of batteries, the system satisfies the demand for an environmentally friendly and dean source of the energy. A complete design example illustrating the amount of hydrogen storage required for 1hr power outage, and sizing of supercacpacitor for transient load demand is presented for a 1-[KVA] UPS.

• Structural Engineering and Mechanics
• /
• v.42 no.3
• /
• pp.409-424
• /
• 2012

Since relatively low elasticity modulus of the FRP materials results in lower natural frequencies, it is necessary to study the free vibration of FRP transmission poles. In this paper, the free vibration of tapered FRP transmission poles with thin-walled circular cross-section is investigated by a tapered beam element. To model the flexible joints of the modular poles, a rotational spring model is used. Modal analysis is performed for typical FRP poles with/without joint and they are also modeled by ANSYS commercial finite element software. There is a good correlation between the results of the tapered beam finite element model and those obtained from ANSYS as well as the existing experimental results. The effects of different geometries, material lay-ups, concentrated masses at the pole tip, and joint flexibilities are evaluated. Moreover, it is concluded that using tougher fibres at the inner and outer layers of the cross-section, results in higher natural frequencies, significantly.