• Progress in Superconductivity and Cryogenics
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• v.14 no.1
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• pp.8-13
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• 2012

We already fabricated a proto-type HTS charging system with photovoltaic (PV) system and obtained design parameters for DC converter and HTS charging system. In order to develop the real scale charging system efficiently, we suggested a maximum power point tracking (MPPT) controller using a perturb and observe (P&O) MPPT algorithm for PV system. In this paper, we designed and simulated the MPPT controller for the real scale HTS charging system. As well as, the PV module has been analyzed by solving solar cell equivalent equations. The simulated and theoretical results presented here are being considered the next study which addresses the design and fabrication parameters.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2002.12a
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• pp.113-117
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• 2002

PID controllers, which have been widely used in industry, have a simple structure and robustness to modeling error. But it is difficult to have uniformly good control performance in system parameters variation or different velocity command. In this paper, we propose a nonlinear adaptive PR controller based on an Immune feedback mechanism and a gradient descent teaming. This algorithm has a simple structure and robustness to system parameters variation. To verify performances of the proposed nonlinear adaptive PID controller, the speed control of nonlinear DC motor Is peformed. The simulation results show that the proposed control systems are effective in tracking a command velocity under system parameters variation

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.2B no.4
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• pp.214-218
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• 2002

In this paper, the effectiveness of three different control algorithms are thoroughly investigated via simulation and a proposed efficiency evaluation method of experimentation. Both the steady state and transient characteristics of each control algorithm along with its measured efficiency are analyzed. Finally, a novel two-mode maximum power point tracking (MPPT) control algorithm combining the constant voltage control and the incremental conduction (IncCond) methods is proposed to improve the efficiency of the 3KW PV power generation system at different insolation conditions. Experimental results show that the proposed two-mode MPPT control provides excellent performance at less than 30% insolation intensity, covering the whole insolation area without additional hardware circuitry.

• Proceedings of the KIPE Conference
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• 2008.10a
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• pp.42-44
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• 2008

연료전지가 동작할 때에는 공기공급을 위한 압축기가 동작하게 되는데 공기의 유량에 따라 연료전지의 출력전력이 달라진다. 또한 공기의 유량에 따라 압축기에서 소비하는 전력이 달라지기 때문에 공기 유량에 따른 연료전지의 최대 효율점이 존재하게 된다. 본 논문에서는 연료전지의 출력전력에서 압축기의 손실전력을 제외한 순수 파워를 최대로 낼 수 있는 유량을 추적 제어하는 알고리즘을 제안한다.

• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.204-207
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• 2004

The paper proposes a simulation model of grid-connected photovoltaic generation system (PV system) using on PSCAD/EMTDC, a reliable power system and apparatus transient analysis program. A equivalent circuit model of a solar cell is used for modeling solar array. A series of parameters required for array modeling are deduced from general specification data of a solar module. A PWM voltage source inverter (VSI) model is presented and current control scheme is implemented for VSI control. A maximum power point tracking (MPPT) technique is applied for controlling the PV system. Simulation case study provides V-I and V-P characteristics of solar array and PV system control performance for irradiation changes.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.584-587
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• 2006

An energy generating greenhouse based on fluoropolymer envelope and fresnel lens is proposed. The outstanding properties of the fluoropolymer films make them very suitable for large scale solar applications. Extremely high optical transmission over the whole solar spectrum, combined with mechanical strength, and durability allows us to design a highly optimized greenhouses for both plant growing and energy generation. Systems such as photovoltaic triple junction cells are especially attractive since they have up to 35% efficiency with much less cell material when the sun beam is focused with concentrators such as fresnel lenses. Cooling such devices will enhance the efficiency and provide useful thermal energy that could be further utilized for various applications depending on the local demands. This article introduces the basic ideas and principles of the energy generating greenhouses as a first step towards the actual deployment of such systems under Korean environment.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.675-676
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• 2014

Photovoltaic (PV) systems bosed on solar energy offer an environmentally friendly source of electricity. A key feature of such PV sysem is the efficiency of conversion at which the power converter stage can extract the energy from the PV arrays and deliver to the load. The Maximum power point tracking (MPPT) of the PV output for all sunshine conditions allows reduction of the cost installation and maximizes the power output from the PV panel. The proposed algorithm is to control the width of the pulse for battery charging based on the open voltage of the PV panel. As a lab results, the proposed system was implemented functions to adapt to the changes of the PV open voltage, and improved the charging efficiency.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.07a
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• pp.159-160
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• 2019

일반적인 FOCV MPPT는 VOC와 VMPP와의 관계인 ${\alpha}$를 외부에서 지정해준다. 하지만 외부환경 (조도나 온도)에 따라서 태양전지의 ${\alpha}$값이 변화할 가능성이 있다. 본 논문에서는 저전력 IoT 센서의 구동을 위한 태양열 에너지 하베스팅을 위해 IV Curve를 이용한 태양전지 전력 계싼회로를 제안한다. IV Curve를 이용한 태양전지 전력을 직접 계산하여 FOCV MPPT를 개선함으로써 보다 높은 효율의 MPPT가 가능하고 외부환경의 변화에도 충분히 Maximum Power Point Tracking이 가능해지게 된다.

• Journal of IKEEE
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• v.20 no.2
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• pp.167-170
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• 2016

Replica bit-line technique is used for making enable signal of sense amplifier which accurately tracks bit-line of SRAM. However, threshold voltage variation in the replica bit-line circuit changes the cell current, which results in variation of the sense amplifier enable time, $T_{SAE}$. The variation of $T_{SAE}$ makes the sensing operation unstable. In this paper, in addition to conventional replica bit-line delay ($RBL_{conv}$), dual replica bit-line delay (DRBD) and multi-stage dual replica bit-line delay (MDRBD) which are used for reducing $T_{SAE}$ variation are briefly introduced, and the maximum possible number of on-cell which can satisfy $6{\sigma}$ sensing yield is determined through simulation at a supply voltage of 0.6V with 14nm FinFET technology. As a result, it is observed that performance of DRBD and MDRBD is improved 24.4% and 48.3% than $RBL_{conv}$ and energy consumption is reduced which 8% and 32.4% than $RBL_{conv}$.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.4
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• pp.335-342
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• 2016

This paper proposes an energy storage-assisted, series-connected module-integrated power conversion system that integrates a photovoltaic power conditioner and a charge balancing circuit. In conventional methods, a photovoltaic power conditioner and a cell-balancing circuit are needed for photovoltaic systems with energy storage devices, but they cause a complex configuration and high cost. Moreover, an imbalanced output voltage of the module-integrated converter for PV panels can be a result of partial shading. Partial shading can lead to the fault condition of the boost converter in shaded modules and high voltage stresses on the devices in other modules. To overcome these problems, a bidirectional buck-boost converter with an integrated magnetic device operating for a charge-balancing circuit is proposed. The proposed circuit has multiple secondary rectifiers with inductors sharing a single magnetic core, which works as an inductor for the main bidirectional charger/discharger of the energy storage. The secondary rectifiers operate as a cell-balancing circuit for both energy storage and the series-connected multiple outputs of the module-integrated converter. The operating principle of the cell-balancing power conversion circuit and the power stage design are presented and validated by PSIM simulation for analysis. A hardware prototype with equivalent photovoltaic modules is implemented for verification. The results verify that the modularized photovoltaic power conversion system in the output series with an energy storage successfully works with the proposed low-cost bidirectional buck-boost converter comprising a single magnetic device.