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A Dual-Phase-Shift Control Strategy for Dual-Active-Bridge DC-DC Converter in Wide Voltage Range
Myoungho Kim,Martin Rosekeit,Seung-Ki Sul,Rik W. A. A. De Doncker 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
This paper analyzes the dual-phase-shift (DPS) control strategy for a dual-active-bridge (DAB) converter in whole operation range. The DPS has two degree of freedom to control the transferring power, which can improve the performance of the DAB converter than single-phase-shift (SPS) control strategy. This paper derives the reactive power, the rms and the peak current flowing on the transformer and the zero-voltage-switching (ZVS) condition according to the operating conditions. Using this analysis and simulation results, a suitable control strategy for DAB converter is obtained. Experiments are performed to verify the proposed control strategy and to compare with the conventional SPS control strategy. The experimental results show that the proposed method can enhance the overall efficiency and expand the ZVS operation range.
Compensation of Current Measurement Error for Current-Controlled PMSM Drives
Myoungho Kim,Seung-Ki Sul,Junggi Lee IEEE 2014 IEEE transactions on industry applications Vol.50 No.5
<P>Accurate measurement of phase current is crucial in a current-controlled permanent-magnet synchronous machine (PMSM) drive system. Current measurement error directly deteriorates torque control performance. This paper analyzes effects of the current measurement error on the phase current and the output voltage of the current controller. Based on the analysis, a compensation method is proposed. The proposed method compensates the offset and scaling errors separately without any additional hardware but using the commanded voltage reference of the current controller. The proposed method can be applied to general current-controlled PMSM drives in the whole operation range. Experimental results verify the effectiveness of the proposed compensation method.</P>
MyoungHo Kim,Sung-Uk Lee 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.7
The desired performance of nonlinear systems by using only proportional-integral-derivative (PID) controllers is difficult to obtain because of its simple structure. To improve the control performance of nonlinear systems, we proposed a PID with a switching action (PIDSA) controller that only adds the switching action of a sliding mode control (SMC) while maintaining the structure of the PID. The PIDSA controller has the simplicity of PID and the robustness of SMC. In addition, a double integral sliding surface (DISS) was designed to match the characteristics of the PID with the switching action. The stability of the overall system was proved for nonlinear systems by performing the Lyapunov stability analysis. Finally, experiments were conducted on a hydraulic manipulator, which is a highly nonlinear system. The results show that the proposed controller exhibits excellent performance and that DISS enhances the performance compared with using an integral sliding surface.
Modeling and Controller Design for a SEries-Connected Output Universal Link Converter
Myoungho Kim,Seung-Ki Sul,Anno Yoo IEEE 2015 IEEE transactions on industry applications Vol.51 No.5
<P>This paper conducts modeling and controller design for a SEries-connected Output Universal Link (SEOUL) converter. The SEOUL converter was proposed to interface multiple distributed power sources to the grid with a reduced amount of reactive components. It employs a high-frequency (HF) transformer instead of a bulky line-frequency transformer like solid-state transformers (SSTs). In addition, it does not use a large dc-link capacitor at the input side and reduces the size of the input filter. This is inherently possible due to its original operating characteristic. The input phase current is not actively controlled but synthesized indirectly by HF power transfer between input and output sides of the SEOUL converter. Therefore, it is important to properly control the HF power transfer part, on which this paper focuses. An analytic model is developed, and a control strategy is proposed based on the model with a decoupling control method. The developed model and the proposed control method were verified by experiments.</P>
Euiyun Kim,Junsoo Kim,Minkwang Lee,Sunwoo Myoungho 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
Path tracking control is an essential function for autonomous driving systems. These autonomous driving systems require high tracking accuracy, ride comfort, and smoothness of steering action in the controller’s design. In order to satisfy various requirements, model predictive control (MPC) approaches, which derive an optimal steering trajectory with respect to a pre-defined path, have been widely used. The conventional predictive controller is based on a simple bicycle model for estimation of vehicle motion. However, since there is the dissimilarity between the simplified model and the real autonomous vehicle, the conventional controller is limited in the improvement of vehicle maneuvers. To overcome the limitation, dynamics and constraints of an automatic steering system are taken into account as practical control challenges. In this paper, we propose a model predictive control technique by considering dynamics of the automatic steering system. The optimal trajectory of steering angle is obtained by using the quadratic programming (QP) optimization method. The proposed model predictive controller was verified by simulation using a commercial vehicle model. The simulation results show that an improved control performance can be achieved by considering dynamics of automatic steering system.
정합 검증 패턴을 이용한 적응형 계층 육각 탐색의 성능 개선
김명호(Kim Myoungho),곽노윤(Kwak Noyoon) 한국방송·미디어공학회 2007 한국방송공학회 학술발표대회 논문집 Vol.2007 No.-
본 논문은 정합 검증 패턴을 이용한 적응형 계층 육각 탐색의 성능 개선에 관한 것이다. 제안된 방법은 움직임 추정 블록에 시공간적으로 인접한 블록들의 움직임 벡터를 이용하여 움직임 활동도를 정의한 후, 움직임 활동도가 높을 경우 웨이블렛 변환의 다단계 저주파 부영상들로 구성된 피라미드 계층 구조상에서 정합 검증 패턴을 이용한 적응형 계층 육각 탐색을 수행한다. 제안된 방법을 이용할 경우, 정합 검증 패턴을 적용한 검증 과정에서 추가적인 연산량 증가가 초래되지만 이를 상호타협적으로 보상할 수 있는 화질 측면에서의 성능 개선 효과를 기대할 수 있다. 제안된 방법의 타당성과 보편성을 검증하기 위해 서로 다른 움직임 특성을 갖는 복수의 영상 시퀀스들을 대상으로 움직임 보상 화질과 수렴시간 측면에서 그 성능을 분석ㆍ평가하였다. 컴퓨터 시뮬레이션 결과에 따르면, 제안된 방법은 고속 움직임 탐색이 가능한 적응형 계층 육각 탐색의 장점을 유지하면서도 움직임 활동도가 높은 영상 시퀀스에서 야기되는 국부 최소 문제를 효과적으로 억제시킴으로써 보상 화질 측면에서 개선된 성능을 제공할 수 있었다.
컬러 레이저 빔 프린터의 구동단 속도 제어를 통한 인쇄 품질 향상
김명호(Myoungho Kim),임정식(Jung-Sik Yim),설승기(Seung-Ki Sul),김종태(Jongtae Kim) 전력전자학회 2008 전력전자학술대회 논문집 Vol.- No.-
레이저 빔 프린터의 인쇄 품질은 화상 인쇄 과정에 직접적으로 관계되는 OPC 드럼(Organic Photoconductive Drum) 및 PTB(Paper Transfer Belt)의 운전 속도 특성과 관계 있는 것으로 알려져 있다. 그러나 그 관계가 정량적으로 연구된 바는 없었다. 본 논문에서는 인쇄 동작중인 OPC 드럼 및 PTB의 실제 속도를 측정하고, 속도 측정결과에 나타나는 특성이 실제 인쇄 결과에 미치는 영향을 정량적으로 분석한다. 또한 위의 속도 측정 및 분석 결과를 바탕으로 하여 레이저 빔 프린터의 인쇄 품질을 향상시킬 수 있는 방법을 제안하고, 실험을 통해 그 타당성을 검토한다. 제안 된 방법에의해 인쇄 품질의 정도(Accuracy)가 5배이상 개선됨을 확인하였다.