• 전력전자학회논문지
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• 제16권3호
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• pp.209-218
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• 2011

연료전지와 같은 저전압 대전류 응용에는 입력전류 리플이 작고 변압기의 턴비가 작은 전류원 DC-DC 컨버터가 더 효과적이다. 5kW급 이상의 응용에서는 기존의 단상을 기본으로 하는 전류원 풀브리지, 하프브리지 또는 푸시풀 의 토폴로지로는 스위치등 소자의 전류부담이 크고 소자의 선정 및 최적설계가 용이하지 않다. 본 논문에서는 대전력 고승압 응용에 적합한 능동 클램프방식의 3상 전류원 푸쉬풀 DC-DC 컨버터를 제안한다. 제안한 컨버터는 소자의 전류부담이 작고 전 영역(0～1)의 듀티 사용으로 입력전압 변동이 큰 응용에 적합하다. 3상 고주파변압기를 비롯한 주요부품의 설계방법을 제시하고 5kW급의 시작품으로부터 제안한 컨버터의 타당성 및 성능을 검증하였다.

• 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.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권12호
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• pp.701-708
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• 1999

The PWM rectifiers are capable of supplying sinusoidal current control and unity power factor control on the input side and dc output voltage control on the output side. By applying nonlinear control to the PWM rectifiers, the responses of input current and output voltage can be improved and due to fast voltage control the output electrolytic capacitor can be reduced remarkably. In addition, it is checked whether or not the current capacity of the reduced-size capacitor allows the ripple current of the rectifier. The nonlinear control technique gives a good performance for supply voltage disturbances. The validity of the proposed scheme has been verified by the experiment using DSP.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2012년도 전력전자학술대회 논문집
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• pp.232-233
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• 2012

This paper presents an effective control scheme for an electric vehicle battery charger where a symmetrical bridgeless power factor-corrected converter and a buck converter are cascaded. Both converters have been popular in industries because of their high efficiency, low cost, and compact size, hence combining these converters makes the overall battery charging system strongly efficient. Moreover, this charger topology can operate at universal input voltage and attain a desired battery current and voltage without ripple. In order to achieve a unity input power factor and zero input current harmonic distortion, the proposed control scheme adopts duty ratio feed-forward control technique in both current and voltage control loop. Additionally, in the current loop, its reference is created by a phase-locked loop (PLL) block, leading to a pure sinusoidal input current although the input voltage waveform is being distorted. The feasibility and practical value of the proposed approach are verified by simulation and experiment with an 110V/60Hz ac line input and 1.5kW-72V dc output of the battery charging system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.821-824
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• 1993

This paper deals with a $3{\phi}$ rectifier unit for telecommunication system. The rectifier unit is developed to Cope with the step-up of the AC input voltatage from 220V to 380V. By using a buck-type converter in the front-end, it keeps the input power factor high and reduces the voltage ripple in the dc output. It also has a very wide voltage regulation range, which lets the unit be applied for both the 220V and 380V input system. The study includes the power conversion scheme, control strategy, snubber circuit and finally, experimental results.

• Journal of Power Electronics
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• 제17권4호
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• pp.884-891
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• 2017

The improved transfer functions of the modified Sheppard-Taylor (MS-T) converter, which is capable of regulating output voltage under a wide range of input voltage and load variations, negligible current ripple, and fewer components in comparison to the Sheppard-Taylor (S-T) converter, operating in continuous conduction mode (CCM) are investigated in this study. Its DC equilibrium point, small signal model, and transfer functions are derived and analyzed. Then, the voltage controller is applied for this MS-T converter. The comparisons between the derived model and the existing model are presented. The hardware circuit is designed and the circuit experiments are provided for validation. The results show that the improved transfer functions of the MS-T converter are more effective and general than the previous ones for describing its real characteristics.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 추계학술대회
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• pp.193-194
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• 2011

This paper describes a control method to minimize the filter capacitor of a PFC AC/DC converter for LED driver. The rectified secondary voltage of the transformer has 120Hz ripple unlike the conventional converter for the LED drive. Therefore, the filter capacitor can be minimized and this provides reduced cost, low switching loss, and long life of the converter.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 전력전자학술대회
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• pp.9-10
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• 2011

This paper describes a control method to minimize the filter capacitor of a AC/DC converter for LED driver. The rectified secondary voltage of the transformer has 120Hz ripple unlike the conventional converter for the LED drive. Therefore, the filter capacitor can be minimized and this provides reduced cost, low switching loss, and long life of the converter.

• 한국태양에너지학회 논문집
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• 제24권2호
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• pp.89-96
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• 2004

PV system is easy to operate and maintain than the other power generating system since it generally contains no moving parts, operates silently and requires very little maintenance. A solar cell generates DC power from sunlight whose power is different at any instance according to condition of irradiation and temperature variables. In order to improve the system utility factor and efficiency of energy conversion, it is desirable to operate the PV system at maximum power point of solar cell under different condition This paper describes the experimental results of the PV system contain solar modules and a DC-DC converter(boost type chopper) using fuzzy controller. The experimental results show that the PV system always operates at maximum power point of solar cells having stabilized output voltage waveform with relatively small ripple component.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2020년도 전력전자학술대회
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• pp.34-36
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• 2020

본 논문은 전기자동차용 탑재형 충전기에 사용되는 능동 전력 디커플링 회로의 커패시턴스 저감 기법을 제안한다. 탑재형 충전기의 허용 DC-link 전압 리플과 커패시턴스 사이의 관계를 분석하고, 허용 리플 크기에 따른 최적 커패시턴스의 크기를 도출한다. 제안하는 설계 기법은 시뮬레이션 및 실험 결과를 기반으로 검증한다.