• Journal of Power Electronics
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• 제15권4호
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• pp.1026-1034
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• 2015

In this paper, a unified control strategy using the current space vector modulation (CSVM) technique is proposed and applied to a bidirectional three-phase DC/AC converter. The operation of the converter changes with the direction of the power flow. In the charging mode, it works as a buck type rectifier; and during the discharging mode, it operates as a boost type inverter, which makes it suitable as an interface between high voltage AC grids and low voltage energy storage devices. This topology has the following advantages: high conversion efficiency, high power factor at the grid side, tight control of the charging current and fast transition between the charging and discharging modes. The operating principle of the mode analysis, the gate signal generation, the general control strategy and the transition from a constant current (CC) to a constant voltage (CV) in the charging mode are discussed. The proposed control strategy has been validated by simulations and experimental results obtained with a 1kW laboratory prototype using supercapacitors as an energy storage device.

• 전력전자학회논문지
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• 제21권1호
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• pp.19-26
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• 2016

In this study, a bidirectional DC-DC converter for idle stop and go (ISG) is developed to reduce fuel consumption. A three-phase non-isolated half-bridge converter is selected through a design method by considering efficiency and volume. According to the state of charge of the batteries at both the low-voltage and high-voltage sides, buck mode, which charges a low-voltage battery from the generated motor energy, and boost mode, which provides power to the motor from the low- and high-voltage battery sides, are required in the ISG system. Hence, an autonomous and seamless bidirectional control method using a variable current limiter is proposed for mode change. A 1.8 kW engineering sample of the proposed converter has been built and tested to verify the validity of the proposed concept. The maximum efficiencies, including gate driver and control circuit losses, are 96.4% in charging mode and 96.1% in discharging mode.

• 전력전자학회논문지
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• 제15권4호
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• pp.259-265
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• 2010

본 논문에서는 더 높은 에너지 효율을 요구하는 전자 기기들의 사용에 따른 고전력 밀도 AC/DC 어댑터의 구조를 제안한다. PFC (Power Factor Corrector) topology는 BCM (Boundary Conduction Mode)제어 방식을 적용한 Boost topology를 기본으로 하였으며, DC/DC topology는 주파수제어를 적용한 LLC 공진 컨버터를기본으로 하였다. 이는 반도체 소자 및 마그네틱 소자의 크기를 줄이는데 용이하다. 85W급 AC/DC adapter (18.5V/4.6A)를 설계하여 실험한 결과 $90V_{rms}$의 입력전압에서 90%의 효율과 $36W/in^3$의 전력밀도가 측정되었고 무부하시 전력 손실은 0.5W를 달성하였다.

• 정보처리학회논문지A
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• 제17A권3호
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• pp.121-126
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• 2010

본 논문에서는 저 전압 스윙 기술을 적용하여 저 전력 회로를 구현하고, 슬립 트랜지스터 (sleep-transistor)를 이용하여 누설전류를 최소화하는 새로운 저 전력 MOS 전류모드 논리회로 (MOS current-mode logic circuit)를 제안하였다. 제안한 회로는 저 전압 스윙 기술을 적용하여 저 전력 특성을 갖도록 설계하였고 고 문턱전압 PMOS 트랜지스터 (high-threshold voltage PMOS transistor)를 슬립 트랜지스터로 사용하여 누설전류를 최소화하였다. 제안한 회로는 $16\;{\times}\;16$ 비트 병렬 곱셈기에 적용하여 타당성을 입증하였다. 이 회로는 슬립모드에서 기존 MOS 전류 모드 논리회로 구조에 비해 대기전력소모가 1/104로 감소하였으며, 정상 동작모드에서 11.7 %의 전력소모 감소효과가 있었으며 전력소모와 지연시간의 곱에서 15.1 %의 성능향상이 있었다. 이 회로는 삼성 $0.18\;{\mu}m$ CMOS 공정을 이용하여 설계하였으며, HSPICE를 통하여 검증하였다.

• Journal of Electrical Engineering and Technology
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• 제6권1호
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• pp.104-110
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• 2011

High-brightness LED control is required for stable operation, thus the driver and control system must be designed to deliver a constant current to optimize reliability and ensure consistent luminous flux. In this paper, the sliding mode current controller is designed to adjust the illumination density of power LEDs. The controller design model of power LEDs, including its driving circuit, is proposed to realize the dimming control of power LEDs. A buck converter is introduced to drive the power LEDs and reduce the input voltage to a lower level. The sliding mode software controller is implemented to adjust the dimming of power LEDs. The proposed strategy for driving power LEDs is investigated and comparatively studied by experiments.

• 한국전자파학회논문지
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• 제17권4호
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• pp.351-357
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• 2006

본 논문에서는 초고출력용 X-band 협대역 안테나 시스템으로부터 초고출력 에너지를 최대 지향성으로 방사할 수 있도록 확장된 원형 도파관의 입력 $TM_{01}$ 모드를 출력 $TE_{11}$ 모드로 직접 변환하는 장치를 설계하고 그특성을 고찰하였다. 제안된 모드 변환기는 1차 미분 커플링 방정식으로부터 $TM_{01}$와 $TE_{11}$ 모드 사이에 최대 커플링 효과를 갖도록 non-constant serpentine 형태의 비선형 함수에 대한 근사 설계법을 제안하고, X-band 10 GHz의 동작 주파수에서 200 mm의 전체 길이와 95% 이상의 변환 효율 특성을 갖도록 구현되었으며, 기존의 $TM_{01}-TE_{11}$ 직접 모드 변환기와 비교, 분석을 통해 소형, 고효율의 특성을 확인하였다.

• 한국전자파학회논문지
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• 제14권4호
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• pp.363-368
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• 2003

본 논문에서는 고전력을 전송하기 위한 시스템에 사용되는 혼 안테나에 요구되는 특성을 연구하고 그에 따라 여러 혼 안테나의 특성을 비교, 분석하였으며, 최종적으로 다중 모드를 사용하는 원형 혼 안테나를 제안하였다. 고전력 전송 시스템에서는 전력 전송 효율이 매우 중요하며, 이를 위해 반사판 급전 혼 안테나로서 원형의 대칭 적인 방사패턴이 필요하며, 전력 누수와 간섭을 줄이기 위해 부엽이 억제되어야 한다. 뿐만 아니라 다중 모드를 사용함으로써, 혼 안테나의 전체적인 길이를 줄일 수 있고, 반사판 안테나의 형태, 방향에 따라 혼 안테나의 방사 패턴을 자유로이 조절할 수 있다. 또한 제작을 통해 이를 확인하였다.

• 전력전자학회논문지
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• 제25권3호
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• pp.188-194
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• 2020

This paper presents a high-efficiency Switch Mode Line Transformer (SMLT) composed of load-shared dual modules, which is based on the AC/AC LLC resonant converter. Given that the conventional adaptor is usually composed of two power stages, namely, the PFC and DC/DC converters, its system size can be increased according to the output power. However, given that the proposed SMLT can separate the PFC converter from the adaptor, the size reduction of the system can be achieved. Meanwhile, the SMLT with a single module has the limit of the size reduction because of a high resonant current. Thus, it can be configured with dual or multiple modules to reduce the resonant current. Then, their load sharing can be guaranteed by only the proposed transformer structure without an extra current controller. The validity of the proposed converter is proven through a 850-W prototype.

• 전력전자학회논문지
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• 제26권3호
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• pp.176-182
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• 2021

This research proposes a high-frequency circuit that can accurately predict the differential mode noise of single-phase inverters at the circuit design stage. Proposed single-phase inverter high frequency circuit in the work is a form in which harmonic impedance components are added to the basic single-phase inverter circuit configuration. For accurate noise prediction, parasitic components present in each part of the differential noise path were extracted. Impedance was extracted using a network analyzer and Q3D in the measurement range of 150 kHz to 30 MHz. A high-frequency circuit model was completed by applying the measured values. Simulations and experiments were conducted to confirm the validity of the high-frequency circuit. As a result, we were able to predict the resonance point of the differential mode voltage extracted as an experimental value with a high-frequency circuit model within an approximately 10% error. Through this outcome, we could verify that differential mode noise can be accurately predicted using the proposed model of the high-frequency circuit without a separate test bench for noise measurement.

• Steel and Composite Structures
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• 제46권2호
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• pp.221-236
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• 2023

In order to study the seismic response of the main plant of steel reinforced concrete (SRC) structure of the CAP1400 nuclear power plant under the influence of different high-mode vibration, the 1/7 model structure was manufactured and its dynamic characteristics was tested. Secondly, the finite element model of SRC frame-bent structure was established, the seismic response was analyzed by mode-superposition response spectrum method. Taking the combination result of the 500 vibration modes as the standard, the error of the base reactions, inter-story drift, bending moment and shear of different modes were calculated. Then, based on the results, the influence of high-mode vibration on the seismic response of the SRC frame-bent structure of the main plant was analyzed. The results show that when the 34 vibration modes were intercepted, the mass participation coefficient of the vertical and horizontal vibration mode was above 90%, which can meet the requirements of design code. There is a large error between the seismic response calculated by the 34 and 500 vibration modes, and the error decreases as the number of modes increases. When 60 modes were selected, the error can be reduced to about 1%. The error of the maximum bottom moment of the bottom column appeared in the position of the bent column. Finally, according to the characteristics of the seismic influence coefficient αj of each mode, the mode contribution coefficient γj•Xji was defined to reflect the contribution of each mode to the seismic action.