• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.390-391
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• 2013

This paper proposes advanced RFB PCS for islanded environment. To accommodate islanded system, power conditioning needs voltage control authority changing. RFB initial power generating method is proposed for the Islanded PCS. DC-link voltage control authority is changed to PV converter to bidirectional converter by proposed control logic. The control performance has been verified with hardware experiments.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.830-832
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• 1993

In this paper, A voltage source PWM converter which achieves bidirectional power flow between a $3{\phi}$ AC supply and a DC bus voltage is described. And the paper considers both the steady state and transient response of such a device, and develops mathematical models to describe its performance under the digital control system. As a result the AC line current becomes sinusoidal and the input power factor is improved to unity.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.3
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• pp.35-43
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• 2005

Matrix converters have been studied for eliminating dc link of conventional converter-inverter system, and various undulation strategy have been proposed. Therefore, matrix converter have no energy storage component except for small ac later for the elimination of switching ripple, and can be made compact and highly reliable compare with the do link inverter system. Matrix converter, however, directly connected the input and the output terminals by bidirectional static switch. As a result if the input voltage are asymmetrical, and contain harmonics, the influence of the distortions directly appear on the output terminal. This problem is a major obstacle to the matrix converter. A new control method using average comparison strategy have been proposed in this paper. This control method realizes sinusoidal input and output current unity input displacement factor regardless of load power factor. Moreover, compensation of the asymmetrical and/or harmonic containing input voltage is automatically realized, and calculation time of control function is reduced.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.2
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• pp.21-28
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• 1998

A new technique for shaping the line current and reducing the total hannonic distortion in a threephase rectifier is introduced. A review of the problems inherent in a three-phase diode rectifier feeding capacitive load and the possible solutions are first presented. The proposed 3 bidirectional switches and their operation are presented. The main features of this paper are low cost, high efficiency and simplicity. A simulation and experiment results show its good action.action.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.4
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• pp.297-304
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• 2015

A conventional single-phase high-power system typically generates a large AC line input current at universal 90 VAC condition. Sometimes, this phenomenon can block the Earth Leakage Circuit Breaker (ELCB), which causes problems. Replacing power facilities is essential to ensure smooth operations. Thus, this paper proposes a method that can drive higher power than the limit of conventional power facilities. The proposed method can reduce the large AC line input current by limiting the input power of Power Factor Correction (PFC). An additional battery circuit can supplement the power deficiency. Specifically, a bidirectional converter with charging and discharging functions was adopted for the battery circuit. Finally, the validity of the proposed system could be confirmed by modal analysis and simulation, and an experiment in 2 KW condition was implemented with a prototype sample as well.

• Proceedings of the KIPE Conference
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• 2014.11a
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• pp.13-14
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• 2014

본 논문에서는 유사 DC-Link 타입의 태양광 마이크로 인버터에서 요구되는 대용량의 전해 커패시터의 단점을 지적하고 이를 제거하기 위해 shunt 방식으로 연결되는 양방향 벅-부스트 컨버터 제어방법을 제안한다. 태양광 마이크로 인버터는 동작 특성상 PV 입력단에 120Hz 리플이 존재하지만 대용량의 전해 커패시터를 적용함으로써 리플을 제거할 수 있다. 하지만 전해 커패시터의 짧은 수명이 전체 시스템의 신뢰성을 저하시키기 때문에 이를 극복하기 위한 부가적인 회로가 필요하다. 본 논문에서는 제안한 1차측의 플라이백 스위치 전류 제어기의 레퍼런스를 공유함으로써 전류 센서수를 감소시키고 PV 입력단 Capacitance를 낮출 수 있는 양방향 벅-부스트 회로의 제어기를 시뮬레이션을 통하여 검증하였다.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.933-934
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• 2006

본 논문에서는 새로운 양방향 ZVS PWM Sepic/Zeta 컨버터를 제안한다. 제안한 컨버터는 PWM 제어가능한 컨버터로서 입력과 출력전압의 극성이 같은 비반전 컨버터의 특징을 지니며 DC 전압의 전달함수가 양방향 모두 M=D/(1-D)로 동일하다. 또한 각방향으로 전력전달시 다이오드와 병렬로 연결된 MOSFET가 다이오드의 'ON'시 동시에 'ON'되어 Sychronous Rectifier로 동작하므로 도통손을 저감하였으며, Auxiliary Resonant Commutated Pole를 사용하여 저감된 스위칭 손실을 갖는 특성을 지니고 있다. 또한 Transformer 버전이 존재하므로 입력과 출력사잉에 전기적 절연을 필요로 하는 실제응용에 유용하게 사용할 수 있다.

• Journal of Electrical Engineering and Technology
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• v.4 no.2
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• pp.211-218
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• 2009

This paper presents a voltage and frequency controller (VFC) for a 4-wire stand-alone wind energy conversion system (WECS) employing an asynchronous generator. The proposed VF con-troller consists of a three leg IGBT (Insulated Gate Bipolar Junction Transistor) based voltage source converter and a battery at its DC bus. The neutral terminal for the consumer loads is created using a T-connected transformer, which consists of only two single phase transformers. The control algorithm of the VF controller is developed for the bidirectional flow capability of the active power and reactive power control by which it controls the WECS voltage and frequency under different dynamic conditions, such as varying consumer loads and varying wind speeds. The WECS is modeled and simulated in MATLAB using Simulink and PSB toolboxes. Extensive results are presented to demonstrate the capability of the VF controller as a harmonic eliminator, a load balancer, a neutral current compensator as well as a voltage and frequency controller.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.6
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• pp.1154-1162
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• 2016

This paper proposes a fast-transient digital LDO(Low dropout) regulator with binary-weighted current control technique. Conventional digital LDO takes a long time to stabilize the output voltage, because it controls the amount of current step by step, thus ringing problem is generated. Binary-weighted current control technique rapidly stabilizes output voltage by removing the ringing problem. When output voltage reliably reaches the target voltage, It added the FRZ mode(Freeze) to stop the operation of digital LDO. The proposed fast response digital LDO is used with a slow response DC-DC converter in the system which rapidly changes output voltage. The proposed digital controller circuit area was reduced by 56% compared to conventional bidirectional shift register, and the ripple voltage was reduced by 87%. A chip was implemented with a $0.18{\mu}F$ CMOS process. The settling time is $3.1{\mu}F$ and the voltage ripple is 6.2mV when $1{\mu}F$ output capacitor is used.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2004-2012
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• 2014

Energy storage devices are necessary to obtain stable utilization of renewable energy sources. When black-out occurs, distributed renewable power sources with energy storage devices can operate under standalone mode as uninterruptable power supply. This paper proposes a dynamic response analysis with small-signal modeling for the standalone operation of a photovoltaic power generation system that includes a bidirectional charger/discharger with a battery. Furthermore, it proposes a DC-link voltage controller design of the entire power conditioning system, using the storage current under standalone operation. The purpose of this controller is to guarantee the stable operation of the renewable source and the storage subsystem, with the power conversion of a very efficient bypass-type PCS. This paper presents the operating principle and design guidelines of the proposed scheme, along with performance analysis and simulation. Finally, a hardware prototype of 1-kW power conditioning system with an energy storage device is implemented, for experimental verification of the proposed converter system.