• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2057-2059
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• 1998

In order to maintain a high quality output voltage, conventional UPS systems use complex filters with large passive components. To overcome this drawback, real time feedback control schemes have been invested. However, these techniques require a high inverter switching frequency to dynamically adapt to changing load conditions reduce harmonics of the output voltage, thereby rendering the system inadequate for high power applications. This paper presents real time digital signal processor(DSP) control of a large capacity UPS system feeding nonlinear loads to provide a sinusoidal inverter output voltage, unity input power factor, low bus voltage ripple, and excellent transient response.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.386-387
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• 2018

최근 배터리를 사용하는 비상 전력공급시스템에서 무정전전원장치(UPS)의 중요성이 강조되고 있다. UPS는 정전시 부하에 전력을 안정적으로 공급하는 알고리즘이 중요하다. 따라서 본 논문에서는 UPS의 알고리즘 동작을 검증하기 위하여 하이브리드 ESS의 계통 차단 검출 및 독립 운전 제어를 진행하였다. 이를 위해 단상 풀브릿지 인버터와 양방향 DC/DC 컨버터를 사용하여 제어하였다. 계통연계운전과 독립운전 전환 알고리즘의 동작 확인을 위해 시뮬레이션으로 UPS 독립 운전 제어를 검증하였다.

• 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.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.292-295
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• 2001

This paper describes the implementation of UPS system controlled by the DSP. The digital techniques have been used tn overcome the problems of UPS system controlled by analog control circuits. By developing these systems using the digital technique we could increase the reliability and improve the electrical characteristics. And we designed and developed the system which is able to control UPSs and to monitor errors, statuses and actual values transmitted from UPS through internet. The UPSs also impose high demands on battery life time, reliability and energy-efficiency. These requirements can only be met by employing sophisticated battery management system(BMS). Therefore, a highly accurate, universal and inexpensive measuring system for BMS was developed.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.3
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• pp.235-241
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• 2020

In this paper, we propose the bus/bypass synchronization phase lock loop (B-Sync PLL) method using each phase voltage controller of a parallel UPS inverter. The B-Sync PLL included in each phase voltage control system of parallel UPS inverters has the transient response and the phase synchronization error at grid normal or blackout. The validity of this method is verified by simulation and experiment. As a result, the parallel UPS inverters using the proposed method confirmed that the output phase was continuously synchronized when a grid blackout, improving the transient response characteristics for stable load power supply and equal load sharing.

• Proceedings of the KAIS Fall Conference
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• 2004.06a
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• pp.198-202
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• 2004

본 논문에서는 전력 품질 기기의 제어에 있어서 필수적 요소라고 할 수 있는 전원각을 찾는 방법 중에서 PLL에 관하여 기존의 방식들을 먼저 알아보고, UPS 시스템에 적용하기에 적합한 새로운 PLL 방식을 제안하며, 컴퓨터 시뮬레이션을 통해 기존의 방식과의 성능 비교를 통해서 제안된 새로운 PLL 방식의 우수성을 입증한다. 본 논문에서는 기존의 정상분을 추출하여 이용하는 PLL 방식을 UPS에 적합한 형태로 개선한 주파수를 제안한 PLL 방식을 제안하였다. 이 PLL 방식은 기존의 PI 제어기에 주파수 제한기(limiter)와 안티 와인드업(anti-wind up)을 추가하였다. 이것의 기본적인 동작 원리는 기존의 방법들과 같지만, 차이점은 주파수 제한기의 삽입으로 인하여 주파수 변동률을 일정한 범위 내에서 제한할 수 있다는 것이다. 기존의 PLL 방법과 본 논문에서 제안된 주파수를 제한한 PLL 방법의 차이를 알아보기 위하여 동적 전압 보상기로 전압을 보상하는 시뮬레이션을 하였고, 결과적으로 제안된 주파수를 제한한 PLL 방법이 기존의 PLL 방법보다 UPS에 적합함을 입증하였다.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.83-84
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• 2014

This paper proposes the development of double conversion Uninterruptible Power Supply using 3-Level Converter/TNPC Inverter. The Rectifier of proposed system is operating not only 3-Level boost PFC but also battery discharger. The Inverter is converting DC voltage to AC voltage. And in terms of the efficiency, 3-Level TNPC inverter is improved compared to the origin 2-Level type. To verify the validity of proposed system, experiments were carried out.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1413-1415
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• 2005

In paper, propose new partial resonance ZCS PWM controlled High frequency insulating Full-bridge DC/DC converter not using exciting current of high frequency transformer. It is compared with the existing principles in characteristics. It also realizes a widely stabilized ZVS operating using new On-Off control method at synchronized power rectification MOSFET of high frequency insulating transformer secondary. Finally, it is brought over 97[%] measurement -efficiency by proposed DC-DC converter. It is proved effectiveness of new methods using DC UPS PWM rectifier as switching power.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.3
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• pp.240-246
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• 2013

An Uninterruptible Power Supply(UPS) is a system designed to deliver energy during accidents that the AC mains is out of its acceptable limits, without interruption of power flow through the load. Battery Discharger is the device to supply high quality power to the Inverter, when accidents occur, such as Power Failure. The Battery Discharger should have a fast response characteristics. The LLC resonant converter for UPS battery discharger is proposed. The proposed Battery Discharger offers substantial improvements in efficiency, size and cost. The proposed Battery Discharger of UPS approach is a good solution for high power applications above KW. To verify the validity of proposed Battery Discharger, simulations and experiments are carried out.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.2085-2087
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• 1997

The UPS for power plant is mainly used as the critical power supply of power plant. This is very much alike to the general UPS but it requires the special design criteria of power plant. In this study, we designed and develope system according to the design criteria of p plant. In the development of the special system, the designs of IGBT Drive, heat protection and monitoring system, and p components are key techniques. This Paper describes the power circuits, key techniques, the control and monitoring of the developed UPS(DC 125V $3{\Phi}$ 100K Finally, using the UPS we verified superiority through the type test.