• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.753-755
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• 1993

Full Bridge Diode Rectification and Phase Controlled SCR Rectification are the most widely used methods of power conversion($AC{\rightarrow}DC$) in Power Electronic products such as UPS systems. But using these types of converters can lead to the following problems. First, they generate harmonics on the AC input side, which can cause interference in other equipment connected to the same commercial power line. Second, they deteriorate the power factor so that the input power capacity or the equipment becomes larger than the actual rated output capacity. As a means to overcome these problems an IGBT type PWM Converter, which applies a current control algorithm, is proposed. In this paper the enhancement of the converter performance is shown through simulation.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.2
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• pp.196-203
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• 2005

In this paper, a digital controller for satisfying time response requirements for UPS inverters is designed in a fixed sampling time. The CRA (Characteristic Ratio Assignment) is used as the continuous time design method to deal with the problems of overshoot and settling time. The main design approaches are the inward and outward approaches based on a double-loop feedback structure. The continuous-time controller is discretized by the emulation method. The performances of the proposed controller are evaluated through several simulations carried out with Simpower System Toolbox 3.0 from Simulink$^{(R)}.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.14-19
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• 2004

This paper presents two approaches for designing a digital controller of UPS inverter with time response requirements and a fixed sampling time, which are inward and outward approaches based on a double loop feedback structure. In both approaches, the emulation method. is occupied. Thus we first design continuous-time controllers and then obtain digital controllers by using discretization. We apply the characteristic ratio assignment (CRA) in order to achieve the time response specifications. Also, the internal model control has been used for compensating phase delay in outward approach. The performances of the proposed controller are evaluated through several simulations carried out with Simpower system toolbox 3.0 of $Simulink^{(R)}$.

• 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.54-56
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• 2018

본 논문은 평균 전류 분담 기법을 적용한 UPS(Uninterruptible Power Supply) 시스템의 병렬 운전 기법을 제안한다. 각각의 UPS는 전류 정보를 공유하기 위하여 CAN 통신을 사용하며, 이중 루프 방식의 전압, 전류제어기로 구성되어 있다. UPS의 전류 분담 성능을 내부 전류 제어기의 피드백 전류인 인덕터 전류, 커패시터 전류 그리고 통신 시지연에 따라 영향을 분석하고 3상 30kVA급 UPS에 적용하여 그 유효성을 검증하였다.

• 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.22 no.6
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• pp.535-542
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• 2017

This paper proposes a simple 3-level interleaved charger-discharger for the uninterruptible power supply (UPS) with various combinations of battery cells. The proposed converter not only improves charging and discharging efficiency, but also reduces the physical volume and the cost. Furthermore, the converter also offers the capability of the neutral point voltage, so that more stable operation can be obtained. In addition, the proposed converter significantly reduces the ripple current of the battery inductor, thereby providing an expected life extension of the battery. Experimental results for a 300kVA UPS prototype verify the validity of the proposed converter. The proposed charger-discharger is suitable for UPSs and energy storage systems (ESSs) with wide input battery voltage ranges.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.6 no.6
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• pp.49-57
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• 1992

This paper proposes a Intel 8097 single-chip microprocessor based instantaneous voltage control scheme of inverter for UPS(Uninterruptible Power Supply). There microprocessors are used to control the output voltage and frequency of the inverter, the synchronization with by-pass, and the switching of the static switch. And the status and operating conditions of UPS systems is monitored by micro processor. The inverter output voltage is controlled instantaneously with a double regulation loop so that it has very good dynamic response for the varying loads or nonlinear loads as a rectifier. And also, the software and hardware of control system is described. From simulation and experimental results, it is shown that the proposed scheme has very good performance.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.761-763
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• 1993

Recently the wide use of the microprocessor requests the UPS systems to have various functions. This paper describes the action of peripheral anti internal controller, and the display for current conditions and self-diagnosis such as over load and system fault, and the control algorithm design of UPS system with 1-1.5KW ratings. IBM PC/AT is used as the control system and Turbo PASCAL Ver 5.5 as control language.

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