• 전력전자학회논문지
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• 제10권2호
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• pp.169-176
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• 2005

본 논문에서는 능동 클램프 풀브릿지 Boost 컨버터에 관한 DC 모델링과 AC 모델링 과정에 대하여 기술한다. 동작 원리로부터 이 컨버터의 교류 부분을 등가의 직류 부분으로 바꾸고 반도체 스위치를 재배치하여 개념적인 등가 회로가 유도된다. 유도된 등가회로는 CCM(Continuous conduction mode) Boost 컨버터와 DCM(Discontinuous conduction mode) Buck 컨버터로 표현된다. 유도된 등가회로의 각 스위치 부분을 PWM 스위치 모델로 대체하여 DC 모델 및 AC 모델이 완성된다. 이론적인 DC 및 AC 모델링 결과는 실험이나 SIMPLIS 시뮬레이션을 통해 검증된다.

• 조명전기설비학회논문지
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• 제23권12호
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• pp.127-135
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• 2009

본 연구에서는 2개의 인덕터를 이용한 인터리브 AC/DC 승압형 컨버터의 듀티 사이클이 0.5 이상일 때 배압 회로 특징을 나타내었다. 일반적으로 AC/DC 승압형 컨버터는 낮은 입력전압(입력 AC 110[V])이 높은 입력전압(입력 AC 220[V])에 비하여 낮은 효율을 갖는다. 제안된 인터리브 AC/DC 승압형 컨버터는 낮은 입력전압에서 배압 회로로 동작함으로 인하여 낮은 입력전압을 사용하는 기존의 컨버터와 비교하여 높은 역률과 향상된 효율을 갖는다. 본 연구에서는 배압 회로 동작하는 하는 인터리브 AC/DC 승압형 컨버터를 제안하고, 모드별 해석과 특성을 논의하였으며, 300[W]급 시작품을 제작하여 그 타당성을 검증하였다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2007년도 춘계학술대회 논문집
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• pp.187-192
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• 2007

The terminal voltage of a synchronous generator is maintained by the field current control of excitation system Generally AC/DC converter which is component of AVR(Automatic Voltage Regulator) system for excitation current control is connected to diode rectifier and DC/DC converter system In the case of diode rectifier system of phase controlled converter, AC/DC converter has low power factor and some low order harmonics in the line current. In this paper, two-stage three-phase PWM AC/DC converter is studied to solve these problems, The proposed method is verified by the computer simulations and experimental results in prototype generation system.

• 전력전자학회논문지
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• 제19권3호
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• pp.276-282
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• 2014

In a single-phase grid-connected power system consisting of a dc-dc converter and a dc-ac converter, the current drawn from renewable energy sources has a tendency to be pulsated and contains double-fundamental frequency ripple components, which results in several drawback such as a power harvesting loss and a shortening of the energy source's life. This paper presents a new double-fundamental current reduction-scheme with a fast dc-link voltage loop for two-stage dc-dc-ac grid connected systems. In the frequency domain, an adequate control design is performed based on the small-signal transfer function of a two-stage dc-dc-ac converter. To verify the effectiveness of proposed control algorithm, a 1 kW hardware prototype has been built and experimental results are presented.

• Journal of Electrical Engineering and Technology
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• 제9권5호
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• pp.1537-1543
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• 2014

This paper presents a new DC/AC multilevel converter. This configuration uses single DC sources. The proposed converter has two stages. The first stage is a DC/DC converter that can produce several DC-links in the output. The DC/DC converter is one type of boost converter and uses single inductor. The second stage is a multilevel inverter with several capacitor links. In this paper, one single input multi output DC-DC converter is used in order to voltage balancing on multilevel converter. In addition, as compare to traditional multilevel inverter, presented DC/AC multilevel converter has less on-state voltage drop and conduction losses. Finally, in order to verify the theoretical issues, simulation and experimental results are presented.

• Journal of Power Electronics
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• 제8권1호
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• pp.1-9
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• 2008

This paper presents the design and analysis of a new input AC current wave shaping AC-DC converter for cost effective harmonic mitigation under varying loads. The proposed converter consists of a delta-polygon connected autotransformer based twelve-pulse AC-DC converter and a small rating passive shunt filter tuned at $11^{th}$ harmonic frequency. The proposed AC-DC converter eliminates the most dominant $5^{th},\;7^{th}$ and $11^{th}$ harmonics and reduces higher order harmonics; thereby, resulting in an improved power quality at AC mains. Moreover, the design of the autotransformer is modified to make it suitable for retrofit applications, where presently a 6-pulse diode bridge rectifier is used. To validate the proposed approach, various power quality indices are presented under varying loads. Experimental results obtained on the developed converter are given to validate the model and design of the proposed converter.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.401-404
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• 1998

This paper proposes a new soft switching single stage AC/DC full bridge converter with unit power factor and isolated output. This circuit shows that it is possible to combine the boost converter which is for PFC(Power Factor Correction) and full bridge converter which is for DC/DC converter. A simple auxiliary circuit which includes neither lossy components nor active switches eliminates ringing of secondary side of the transformer. The characteristics of the proposed circuit are investigated and the validity is verified by the simulation results.

• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.165-175
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• 2015

Energy storage system has been widely applied in power distribution sectors as well as in renewable energy sources to ensure uninterruptible power supply. This paper presents a model predictive algorithm to control a bidirectional AC-DC converter, which is used in an energy storage system for power transferring between the three-phase AC voltage supply and energy storage devices. This model predictive control (MPC) algorithm utilizes the discrete behavior of the converter and predicts the future variables of the system by defining cost functions for all possible switching states. Subsequently, the switching state that corresponds to the minimum cost function is selected for the next sampling period for firing the switches of the AC-DC converter. The proposed model predictive control scheme of the AC-DC converter allows bidirectional power flow with instantaneous mode change capability and fast dynamic response. The performance of the MPC controlled bidirectional AC-DC converter is simulated with MATLAB/Simulink(R) and further verified with 3.0kW experimental prototypes. Both the simulation and experimental results show that, the AC-DC converter is operated with unity power factor, acceptable THD (3.3% during rectifier mode and 3.5% during inverter mode) level of AC current and very low DC voltage ripple. Moreover, an efficiency comparison is performed between the proposed MPC and conventional VOC-based PWM controller of the bidirectional AC-DC converter which ensures the effectiveness of MPC controller.

• 전기학회논문지
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• 제58권7호
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• pp.1349-1355
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• 2009

This paper is studied on a novel power factor correction (PFC) AC-DC converter of high efficiency by soft switching technique. The input current waveform in the proposed converter is got to be a sinusoidal form composed of many a discontinuous pulse in proportion to the magnitude of a ac input voltage under the constant switching frequency. Therefore, the input power factor is nearly unity and the control method is simple. The proposed converter adding an electric isolation operates with a discontinuous current mode (DCM) of the reactor in order to obtain some merits of simpler control, such as fixed switching frequency, without synchronization control circuit used in continuous current mode (CCM). To achieve the soft switching (ZCS or ZVS) of control devices, the converter is constructed with a new loss-less snubber for a partial resonant circuit. It is that the switching losses are very low and the efficiency of the converter is high, Particularly, the stored energy in a loss-less snubber capacitor recovers into input side and increases input current from a resonant operation. The result is that the input power factor of the proposed converter is higher than that of a conventional PFC converter. This paper deals mainly with the circuit operations, theoretical, simulated and experimental results of the proposed PFC AC-DC converter in comparison with a conventional PFC AC-DC converter.

• 조명전기설비학회논문지
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• 제29권6호
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• pp.42-48
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• 2015

DC distribution system is difficult to compose the single-system because of the capacity restriction of power semiconductors. Therefore, DC Distribution system needs parallel operation of AC/DC converters for increase to system capacity. However, this system generates the circulating current. This paper is reducing the circulating current and safely sharing the load using the proposed DC current droop control method when each other 3-phase AC/DC converter connected. This system confirms through the simulation and experiment. Also, when each other converter of parallel operate. it is compared the response characteristics