• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.2675-2677
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• 2000

본 논문에서는 광대역 입력전압에 대응 할 수 있는 직류 변환 장치(DC-DC Converter)의 제어기의 모델링 및 제어 방법에 대해서 제안한다. 일반적으로 직류 변환 장치의 주된 목적은 입력되는 직류 전압에 대해서 출력전압을 지속적이고 안정적으로 유지해 주는 것이다. 따라서, 안정적인 출력 전압을 얻는 방법으로서 제어되지 않은 직류 변환 장치에 입력전압을 안정적으로 공급해주는 방법도 고려해 볼 수 있으나, 이릴 경우 입력전류의 변화나 입력 전압이 지속적으로 변하는 경우에 대처 하기 어렵다. 따라서, 이러한 문제점들을 해결하기 위해서 출력전압을 궤환 시키고 이 신호에 의해 직류 변환 장치를 제어하는 방법을 고려한다. 또한, 단순한 제어기를 사용할 경우 그 입력전압의 범위가 소자의 한계와 안정성으로 인하여 국한적으로 한정되므로, 이러한 문제를 해결하기 위해 다수의 컨버터를 연결하고 이것을 프로세서를 사용하여 제어하는 방법을 설계한다. 모델링된 직류 변환 장치는 불연속선형 시스템(Piecewise Linear System)으로 해석되어 질 수 있으며, 아울러 각기 다른 입력 범위에서 동작하는 컨버터들에 대해서도 모델링되어야 한다. 또한 일정 간격의 입력 범위내에서 서로 다른 컨버터들을 동작시켜 줄 수 있는 방법도 고려한다. MATLab을 이용하여 파워 컨버터의 성능을 입증하고, 아울러 실제 회로의 실험을 통하여 결과를 검증한다.

• Journal of Power Electronics
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• 제13권3호
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• pp.390-399
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• 2013

As a result of the depletion of fossil fuels and environmental contamination, it has become important to use renewable energy. For the stable utilization of renewable energy sources, energy storage devices must be used. In addition, renewable and distributed power sources with energy storage devices must operate stably under grid-connected mode. This paper proposed dynamic response modeling for renewable power generation systems including a charger/discharger with an energy storage device in order to derive a method to guarantee stable operation while fully utilizing the energy from the energy storage device. In this paper, the principle operation and design guidelines of the proposed scheme are presented, along with a performance analysis and simulation results using MATLAB and PSIM. Finally, a hardware prototype of a 1kW power conditioning system with an energy storage device has been implemented for experimental verification of the proposed converter system.

• 전기학회논문지
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• 제63권1호
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• pp.184-190
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• 2014

Fuel cell power system, unlike conventional energy sources, converts chemical energy into electrical energy through electrochemical reaction of hydrogen and oxygen. In recent years, railway field as well as mobile fuel cell power system is being studying actively with development of hydrogen storage technologies. This paper presents the feasibility study on small-scale prototype electric railway vehicle application using fuel cell generation system. it is confirmed that proposed fuelcell-battery hybrid system shows good response characteristic about speed and torque based on design of parameter on system. Also as results of response for proposed system modeling, it show that powering mode and braking mode of system is controlled by switching devices of converters.

• 한국산학기술학회논문지
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• 제7권6호
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• pp.1092-1099
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• 2006

본 논문에서는 유도전동기를 인버터와 같은 전력변환장치를 사용하여 정상상태의 동작특성은 물론 과도특성까지 해석하기 위해서는 유도전동기와 부하를 포함하는 전체 시스템의 정확한 동적 모델링을 이용하여 시스템 방정식으로 표현해야 한다. 또한 최대 견인력 제어를 위해서 속도센서리스벡터제어와 부하 토크 외란 관측기를 통하여 점착력 계수를 추정한다. 이와 같은 시스템의 제어 알고리즘을 구현하기 위하여 철도 모의 장치를 이용하여 제안된 알고리즘을 시뮬레이션과 실험을 통하여 확인하고, 철도 차량의 속도 가감에 따른 공전속도에 대한 점착력의 관계 등 제반 사항을 모의 장치에 의해서 구현하였다.

• Journal of Power Electronics
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• 제18권6호
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• pp.1683-1696
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• 2018

Under the conventional control strategy, the asymmetry of arm impedances may result in the poor operating performance of modular multilevel converters (MMCs). For example, fundamental frequency oscillation and double frequency components may occur in the dc and ac sides, respectively; and submodule (SM) capacitor voltages among the arms may not be balanced. This study presents an enhanced control strategy to deal with these problems. A mathematical model of an MMC with asymmetric arm impedance is first established. The causes for the above phenomena are analyzed on the basis of the model. Subsequently, an enhanced current control with five integrated proportional integral resonant regulators is designed to protect the ac and dc terminal behavior of converters from asymmetric arm impedances. Furthermore, an enhanced capacitor voltage control is designed to balance the capacitor voltage among the arms with high efficiency and to decouple the ac side control, dc side control, and capacitor voltage balance control among the arms. The accuracy of the theoretical analysis and the effectiveness of the proposed enhanced control strategy are verified through simulation and experimental results.

• Journal of Power Electronics
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• 제18권6호
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• pp.1659-1669
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• 2018

An improved circulating current suppression control method is proposed in this paper. In the proposed controller, an outer loop of the average capacitor voltage control model is used to balance the sub-module capacitor voltage. Meanwhile, an individual voltage balance controller and an arm voltage balance controller are also used. The DC and harmonic components of the circulating current are separated using a low pass filter. Therefore, a multiple quasi-proportional-resonant (multi-quasi-PR) controller is introduced in the inner loop to eliminate the circulating harmonic current, which mainly contains second-order harmonic but also contains other high-order harmonics. In addition, the parameters of the multi-quasi-PR controller are designed in the discrete domain and an analysis of the stability characteristic is given in this paper. In addition, a simulation model of a three-phase MMC system is built in order to confirm the correctness and superiority of the proposed controller. Finally, experiment results are presented and compared. These results illustrate that the improved control method has good performance in suppressing circulating harmonic current and in balancing the capacitor voltage.

• Journal of Power Electronics
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• 제17권4호
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• pp.1088-1096
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• 2017

Load variations on a distribution line result in voltage fluctuations at the point of common coupling (PCC). In order to keep the magnitude of the PCC voltage constant at its rated value and obtain zero voltage regulation (ZVR), a D-STATCOM is installed for voltage correction. Moreover, the ZVR mode of a D-STATCOM can also be used to balance the source current during unbalanced loading. For medium voltage and high power applications, a D-STATCOM is realized by the cascaded H-bridge topology. In the ZVR mode, the D-STATCOM may draw unbalanced current and in this process is required to handle different phase powers leading to deviations in the cluster voltages. Zero sequence voltage needs to be injected for ZVR mode, which creates circulating power among the phases of the D-STATCOM. The computed zero sequence voltage and the individual DC capacitor balancing controller help the DC cluster voltage follow the reference voltage. The effectiveness of the control scheme is verified by modeling the system in MATLAB/SIMULINK. The obtained simulations are further validated by the experimental results using a dSPACE DS1106 and five-level D-STATCOM experimental set up.

• 한국산업융합학회 논문집
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• 제23권6_2호
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• pp.999-1006
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• 2020

This study was conducted to develop an efficiency prediction program of a hydraulic secondary energy converter for calculating annual power generation of a Wavestar type wave power generator. Using the period and wave height obtained from the frequency domain analysis, the behavior of the floating body was obtained by assuming the sin function. The piston displacement and speed of the hydraulic cylinder were calculated considering the behavior of the floating body and the shape of the mechanism. The numerical simulation of the hydraulic system was performed by physically modeling the hydraulic cylinders, check valves, hydraulic motors, which are the main devices. In the future, this analysis program will be used to develop a program for estimating annual power generation of a moveable body type wave power generation device.

• 전력전자학회논문지
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• 제27권6호
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• pp.507-514
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• 2022

This study proposes an optimal design process for a high-frequency transformer that has a large leakage inductance for dual-active-bridge converters. Notably, conventional design processes have large errors in designing leakage transformers because mathematically modeling the leakage inductance of such transformers is difficult. In this work, the geometric parameters of a shell-type transformer are identified, and finite element analysis(FEA) simulation is performed to determine the magnetization inductance, leakage inductance, and copper loss of various shapes of shell-type transformers. Regression models for magnetization and leakage inductances and copper loss are established using the simulation results and the machine learning technique. In addition, to improve the regression models' performance, the regression models are tuned by adding featured parameters that consider the physical characteristics of the transformer. With the regression models, optimal high-frequency transformer designs and the Pareto front (in terms of volume and loss) are determined using NSGA-II. In the Pareto front, a desirable optimal design is selected and verified by FEA simulation and experimentation. The simulated and measured leakage inductances of the selected design match well, and this result shows the validity of the proposed design process.

• 한국수소및신에너지학회논문집
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• 제35권2호
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• pp.121-128
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• 2024

In this study, a dynamic simulation model of a heavy-duty truck, equipped with a fuel cell power-train, has been developed and the dynamic behavior of the fuel cell stack has bee investigated using. Output change simulations were performed according to several drive cycle load change of a fuel cell truck. Mathworks' Simulink and Simscape program were used to develop the model. The model is comprised of fuel cell power train, power converter system and truck vehicle part. The vehicle runs at targeted speed of the truck, which is set as the load of the system. The dynamic behavior of the fuel cell stack according to the weight difference were analyzed, and based on this, the dynamic characteristics of the fuel cell output power and battery state with simple load was analyzed.