• 제목/요약/키워드: UPS inverter

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무정전 전원장치 효율 향상에 대한 연구 (Efficiency Improvement of Uninterruptible Power Supply Systems)

  • 오홍일;권종원;박용만;오드게럴;김희식
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2006년도 심포지엄 논문집 정보 및 제어부문
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    • pp.288-290
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    • 2006
  • An efficiency improving method for Uninterruptible Power Supply System(UPS) was developed by using OP-AMP based application circuits such as voltage detection device, current detection device and static switch control device. The efficiency improving algorithm was made by mixing the operating concepts of On-Line type UPS with the operating concepts of Off-Line type UPS. The UPS' inverter does not work if the UPS' output load current is not higher than the low load operating current which is about 0-30(%) of the UPS' output load capacity. The low load operating current is adjustable within the half of the UPS' output load capacity. If the UPS' output load current is rising over than the low load operating current, the UPS' inverter starts working and the inverter output power feeds to the loads of UPS. If UPS' input power breaks out while UPS' inverter does not operate because the load current is low, the inverter starts working within 4(ms) with excessive output voltage which is ${\pm}$8(%) of normal UPS' output voltage. Like these. UPS can continuously feeds power to it's load device and reduce power consumptions.

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저항성 수하 제어를 적용한 3상 모듈형 UPS 인버터의 비통신선 방식 병렬 운전 (Wireless Parallel Operation of a Three-phase Modular UPS Inverter using Resistive Droop Control)

  • 김선태;지준근
    • 전기학회논문지
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    • 제65권10호
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    • pp.1672-1681
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    • 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.

A Study on a Single-Phase Module UPS using a Three-Arm Converter/Inverter

  • Choi Y.K.;Ko T.G.
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2003년도 춘계전력전자학술대회 논문집(2)
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    • pp.987-993
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    • 2003
  • The module UPS can flexibly implement expansion of power system capacities. Furthermore, it can be used to build up the parallel redundant system to improve the reliability of power system operation. To realize the module UPS, load sharing without interconnection among parallel connecting modules as well as a small scale and lightweight topology is necessary. In this paper, the three-arm converter/inverter is compared with the general full-bridge and half-bridge topology from a practical point of view and chosen as the module UPS topology. The switching control approaches based on a pulse width modulation of the converter and inverter of the system are presented independently The frequency and voltage droop method is applied to parallel operation control to achieve load sharing. Two prototype 3kVA modules are designed and implemented to confirm the effectiveness of the proposed approaches. Experimental results show that the three-arm UPS system has a high power factor, a low distortion of output voltage and input current, and good load sharing characteristic.

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연산시간지연 및 민감성을 고려한 UPS 인버터용 2차 데드비트 제어기 (2nd Order Deadbeat Controller Considering Calculation Time Delay and Sensitivity for UPS Inverter)

  • 김병진;최재호
    • 대한전기학회논문지:전기기기및에너지변환시스템부문B
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    • 제50권4호
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    • pp.170-178
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    • 2001
  • Deadbeat technique has been proposed as a digital controller for an UPS inverter to achieve the fast, response to a load variation and to conserve a very low THD under a nonlinear load condition. This scheme contains a fatal drawback, sensitivity against parameter variation and calculation time delay. This paper proposes a second order deadbeat controller, which fundamentally solves the calculation time delay problem and certainly guarantees the robustness of the parameter's variation. RLP(Repetitive Load Predictor) which predicts the load current ahead of two sampling time and FVR(Fundamental Voltage Regulator) which eliminates the fundamental errors of the output voltage are also proposed for the second order deadbeat controller to apply to UPS inverter systems. These are shown theoretically and practically through simulation and experiment.

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3상 오프라인 무정전 전원 시스템의 돌입전류 제거 (Inrush Current Elimination for a Three-Phase Off-Line UPS System)

  • ;권병일
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2015년도 제46회 하계학술대회
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    • pp.944-945
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    • 2015
  • Many sensitive loads always rely on UPS systems to maintain continuous power during abnormal utility power conditions. As any disturbance occurs at the utility side, an off-line UPS system takes over the load within a quarter cycle to avoid a blackout. However, the starting of the inverter can root the momentous inrush current for the transformer installed before the load, due to its magnetic saturation. The consequences of this current can be a reduction of line voltage and tripping of protective devices of the UPS system. Furthermore, it can also damage the transformer and decrease its lifetime by increasing the mechanical stresses on its windings. To prevent the inrush current, and to avoid its disruptive effects, this paper proposes an off-line UPS system that eliminates the inrush current phenomenon while powering the transformer coupled loads, using a current regulated voltage source inverter (CRVSI) instead of a typical voltage source inverter (VSI). Simulations have been performed to validate the operation of proposed off-line UPS system.

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UPS inverter의 2차 데드비트 응답을 위한 반복부하예측기법 (Repetitive Load Prediction for Second Order Deadbeat Response Applied to UPS Inverter)

  • 최재호
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2000년도 전력전자학술대회 논문집
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    • pp.339-342
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    • 2000
  • Repetitive Load Prediction is proposed for the UPS inverter application of the second order deadbeat controller which is robust against the calculation time delay and the parameter variation and which gets fast response against the load variation. The proposed technique predicts the load current ahead of two sampling time using that the load current is periodic. This is effective under nonlinear load condition. The proposed technique is derived theoretically and verified through simulation and experimental result.

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A Study on a Single-Phase Module UPS using a Three-Arm Converter/Inverter

  • Koo, Tae-Geun;Byun, Young-Bok;Joe, Ki-Yeon;Kim, Dong-Hee;Kim, Chul-U
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • 제3B권1호
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    • pp.44-51
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    • 2003
  • The module UPS can flexibly implement expansion of power system capacities. Further-more, it can be used to build up the parallel redundant system to improve the reliability of power system operation. To realize the module UPS, load sharing without interconnection among parallel connecting modules as well as a small scale and lightweight topology is necessary. In this paper, the three-arm converter/inverter is compared with the general full-bridge and half-bridge topology from a practical point of view and chosen as the module UPS topology. The switching control approaches based on a pulse width modulation of the converter and inverter of the system are presented independently. The frequency and voltage droop method is applied to parallel operation control to achieve load sharing. Two prototype 3㎸A modules are designed and implemented to confirm the effectiveness of the pro-posed approaches. Experimental results show that the three-arm UPS system has a high power factor, a low distortion of output voltage and input current, and good load sharing characteristics.

Cost-Effective APF/UPS System with Seamless Mode Transfer

  • Lee, Woo-Cheol
    • Journal of Electrical Engineering and Technology
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    • 제10권1호
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    • pp.195-204
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    • 2015
  • In this paper, the development of a cost-effective active power filter/uninterruptible power supply (APF/UPS) system with seamless mode transfer is described. The proposed scheme employs a pulse-width-modulation (PWM) voltage-source inverter and has two operational modes. First, when the source voltage is normal, the system operates as an APF, which compensates for the harmonics and power factor while boosting the DC-link voltage to be ready for the disturbance, without an additional DC charging circuit. A simple algorithm to detect the load current harmonics is also proposed. Second, when the source voltage is out of the normal range (owing to sag, swell, or outage), it operates a UPS, which controls the output voltage constantly by discharging the DC-link capacitor. Furthermore, a seamless transfer method for the single-phase inverter between the APF mode and the UPS mode is also proposed, in which an IGBT switch with diodes is used as a static bypass switch. Dissimilar to a conventional SCR switch, the IGBT switch can implement a seamless mode transfer. During the UPS operation, when the source voltage returns to the normal range, the system operates as an APF. The proposed system has good transient and steady-state response characteristics. The APF, charging circuit, and UPS systems are implemented in one inverter system. Finally, the validity of the proposed scheme is investigated with simulated and experimental results for a prototype APF/UPS system rated at 3 kVA.

3상 UPS 인버터의 출력전압 왜형률 개선을 위한 고조파 보상기법의 DSP 제어 (DSP Control of Three-Phase UPS Inverter with Output Voltage Harmonic Compensator)

  • 변영복;조기연;박성준;김철우
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 1997년도 전력전자학술대회 논문집
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    • pp.269-275
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    • 1997
  • This paper presents real time digital signal processor(DSP) control of UPS system feeding processor(DSP) control of UPS system feeding nonlinear loads to provide sinusoidal inverter output voltage. The control scheme is composed of an rms voltage compensator, the load current harmonics feed-forward loop for the cancellation of output voltage harmonics, and the output voltage harmonics feedback loop for system stability. The controller employs a Texas Instruments TMS320C40GFL50 DSP.

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정상상태오차 없는 UPS 인버터용 디지털 PID 전압 제어기 (Static-Error-Free Digital PID Voltage Regulator for UPS Inverter)

  • 김병진;최재호
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2000년도 하계학술대회 논문집 B
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    • pp.1227-1229
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    • 2000
  • The output voltage of UPS must not vary according to the load variation But the output voltage varies due to the load variation when a PI voltage regulator is used which has inherently a static state error. This paper presents a static-error-free digital PID voltage regulator for an UPS inverter to overcome additionally the voltage unbalance problem in three Phase system as well as the above problem.

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