• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 추계학술대회
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• pp.199-200
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• 2011

Uninterruptible Power Supply(UPS) is largely divided into passive-standby, line-interactive and double-conversion methods. This paper proposes the double-conversion UPS for low cost and high performance. The proposed UPS are composed of PFC, inverter, battery charger and discharger. Finally, the validity of proposed UPS was verified by experiments.

• 전력전자학회논문지
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• 제8권2호
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• pp.116-127
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• 2003

본 논문에서는 UPS 인버터의 성능 개선을 위하여 출력측 LC 필터의 커패시터 전압과 전류의 2중 제어루프를 구성하고, 2중 제어루프에 디지털 제어시스템을 채택하였다 또한, 디지털 제어기의 연산지연시간을 보상하기 위하여 이러한 연산지연시간을 인버터 플랜트의 고유한 파라미터로 가정하고, 플랜트 모델에 포함시켜 모델링 하였다. UPS 인버터 출련전압의 과도상태 응답특실을 개선하고, 파라미터 변동에 강인한 특성을 얻기 위하여 2중 제어루프에서 내부 전류 제어루프는 내부 모델 제어기를 제안하였다. UPS 인버터 출력전압의 0의 정상상태 오차를 얻기 위하여 외부 전압 제어루프는 비례 제어기와 공진 제어기를 병렬로 연결한 비례-공진 진압제어기를 제안하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 F
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• pp.2587-2589
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• 1999

In this paper, we propose a new control scheme for a PWM inverter using digital control. Digital control has various advantages in comparison with conventional analogue control. It can achieve high frequency switching of inverter and can be little influenced for temperature variations and aging of devices. This digitally-controlled PWM inverter is implemented using a Digital Signal Processor(DSPTMS320F240). The simulation results are given to verify the DSP based PWM inverter design and implementation.

• 전기학회논문지P
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• 제51권4호
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• pp.175-185
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• 2002

In this paper, a new fully digital current control method of UPS inverter, which is based on an internal model control, is proposed. In the proposed control system, overshoots and oscillations due to the computation time-delay are compensated by explicit incorporation of the time-delay in the current control loop transfer function. The internal model controller is adopted to a second order deadbeat reference-to-output response which means that its response reaches the reference in two sampling time including computational time-delays. That is, the average current of filter capacitor is been exactly equal to the reference current with a time lag of two sampling intervals. Therefore, this method has an essentially overshoot free reference-to-output response with a minimum possible rise time. The effectiveness of the proposed control system has been verified by the simulation and experimental respectively. From the simulation and experimental results, the proposed system is achieved the robust characteristics to the calculation time delay and parameter variation as well as very fast dynamic performance, thus it can be effectively applied to the power supply for the critical load.

• 전력전자학회논문지
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• 제17권4호
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• pp.353-358
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• 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.

• 전기학회논문지P
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• 제62권3호
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• pp.145-150
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• 2013

A novel AC to DC PWM converters with unity input power factor are proposed to overcome the above shortcoming. The main function of these converters is to shape the input line current to force it exactly in phase with the input AC voltage. Therefore, the input power factor can be improved to near unity and the input current harmonics can be eliminated. In this paper, half-bridge converter with two active switches and two diodes are utilized for low-cost type UPS configuration. By having only two semiconductors in the current path at any time, losses can be reduced over the conventional boost topology. Also, this converter provides controllable dc-link voltage, high power factor, and low cost type converter by simple power circuits. Simulation results show that the proposed half-bridge converter/inverter control technique can be applied to single-phase low-cost type UPS systems successfully.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.734-738
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• 2002

In this paper, a novel wireless parallel operation algorithm of N+1 redundant UPS system with no control interconnections is presented. The load sharing of multiple UPS modules are controlled by Q-V droop and $P-\delta$ droop algorithm. This algorithm compensates for inverter parameter variation and line impedance imbalances with wireless auto-tuning method. And to increase the reliability of transient characteristic under parallel operation, a virtual injected Impedance is proposed to decrease a circulation current between inverter modules. Simulation results are provided to prove the novel wireless algorithm.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.50.1-50.1
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• 2011

전력수요가 적을 때 잉여전력을 저장하고 전력수요가 많은 시간대나 전기료가 비싼 시간대에 저장된 전력을 사용함으로서 전력의 활용 효율을 높이고, 전력공급 시스템을 안정화하기 위해 에너지저장시스템의 연구가 최근에 활발히 진행되고 있다. 또한 공장, 산업용빌딩이나 병원 등 고르고 안정적인 전력의 수요는 늘어나고 있으며, 화석 연료 고갈 문제로 인한 신재생에너지 발전의 중요성도 대두되고 있다. 본 논문에서는 무정전 전원장치, 태양광발전시스템, 에너지 저장 시스템을 모두 통합하였다. 제안한 시스템은 3상 인버터, 부스트 컨버터, 양방향 컨버터, 사이리스터 스위치로 구성된다. 인버터는 계통과 연계되거나 UPS 동작 시 AC 전력을 만든다. 부스트 컨버터는 태양광 패널과 연결되어 MPPT 제어를 수행한다. 양방향 컨버터는 잉여전력을 배터리에 저장을 하고, 전력이 부족할 시에는 배터리의 전력을 방전한다. 사이리스터 스위치는 정전 시 계통과 부하를 끊어주는 역할을 한다. 본 논문에서는 15kW급 시스템으로 구현하여 검증하였다.

• 전력전자학회논문지
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• 제25권3호
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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.

• Journal of Power Electronics
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• 제3권4호
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• pp.224-229
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• 2003

The rapid expansion of small computers over the last 10-odd years has brought about great changes in the circumstances affecting UPSs. There are strong demands that UPSs become much smaller and lighter, and more economical, which has resulted in the wide application of the circuit topology without transformer. A disadvantage of such UPS topology is that the DC link voltage is very high, which invites decreased reliability and increased cost of battery bank. Some circuit configurations were proposed to eliminate this disadvantage, but they still had problems. In this paper, a novel circuit configuration which eliminates these problems is proposed and evaluated by the experimental results of prototype UPS.