http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Research on Multiphase Topology of F2F DC Transformer and the Control Method
Shuhuai Shi,Zhuan Zhao,Fang Zhuo,Sheng Cheng,Runchu Ding 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
With the development of HVDC system and medium voltage DC distribution network, DC transformer is needed for voltage level conversion and power transmission. In this paper, a multi-phase face-to-face (F2F) DC transformer topology based on modular multilevel converter (MMC) is proposed to connect two DC systems with different voltage levels and stabilize the lower bus voltage. When the two systems have fixed voltage levels, the topology can increase the transmission power and reduce AC transformer insulation requirements. In this paper, the topology of the proposed DC transformer is introduced, and the control and modulation strategy of the DC transformer are put forward. It can realize large voltage ratio of the system with small ratio AC transformer, and the voltage level conversion of the DC transformer does not depend on the AC transformer. At last, a simulation example is given in MATLAB/Simulink to verify the feasibility of the proposed topology.
Shuhuai Lan(란 슈하이),Hey-Jin Lee(이혜진),Hyoung-Wook Lee(이형욱),Jung-Han Song(송정한),Soo-Hun Lee(이수훈),Jun Ni(준니),Moon G. Lee(이문구) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.5
The aim of this research is to obtain a numerical material model for an amorphous glassy polymer, polycarbonate(PC), which can be used in finite element analysis (FEA) of the micro thermal imprint process near the glass transition temperature. An understanding of the deformation behavior of the PC specimens was acquired by performing tensile stress relaxation tests. The viscoelastic material model based on generalized Maxwell model was introduced for the material near Tg to establish the FE model based on the commercial FEA code ABAQUS/Standard with a suitable set of parameters obtained for this material model from the test data. Further validation of the model and parameters was performed by comparing the analysis of FE model results to the experimental data.
Lan, Shuhuai,Lee, Hey-Jin,Lee, Soo-Hun,Ni, Jun,Lai, Xinmin,Lee, Hyoung-Wook,Song, Jung-Han,Lee, Moon G. Elsevier 2009 MATERIALS AND DESIGN Vol.30 No.9
<P><B>Abstract</B></P><P>The aim of this research is to obtain a numerical material model for an amorphous glassy polymer, polycarbonate (PC), which can be used in finite element analysis (FEA) of the micro thermal imprint process near the glass transition temperature (<I>T<SUB>g</SUB></I>). Through understanding of the deformation behavior of the PC specimens was acquired by performing tensile stress relaxation tests. The viscoelastic material model based on generalized Maxwell model was introduced for the material near <I>T<SUB>g</SUB></I> to establish the FE model based on the commercial FEA code ABAQUS/Standard with a suitable set of parameters obtained for this material model from the test data. Further validation of the model and parameters was performed by comparing the analysis of FE model results to the experimental data. As a result, the feasibility of the established viscoelastic model for PC near <I>T<SUB>g</SUB></I> was confirmed and this material model can be used in FE analysis for the prediction and improvement of the micro thermal imprint process for pattern replication.</P>
열방식 마이크로 임프린트 공정을 위한 고분자 재료의 수치적 모델링과 해석
란 슈하이(Shuhuai Lan),이수훈(Soo-Hun Lee),이혜진(Hye-Jin Lee),송정한(Jung-Han Song),성연욱(Yeon-Wook Sung),김무종(Moojong Kim),이문구(Moon G. Lee) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.10
The research on miniature devices based on non-silicon materials, in particular polymeric materials has been attracting more and more attention in the research field of the micro/nano fabrication in recent years. Lost of applications and many literatures have been reported. However, the study on the micro thermal imprint process of glassy polymer is still not systematic and inadequate. The aim of this research I to obtain a numerical material model for an amorphous glassy polymer, polycarbonate (PC), which can be used in finite element analysis (FEA) of the micro thermal imprint process near the glass transition temperature (Tg). An understanding of the deformation behavior of the PC specimens was acquired by performing tensile stress relaxation tests. The viscoelastic material model based on generalized Maxwell model was introduced for the material near Tg to establish the FE model based on the commercial FEA code ABAQUS/Standard with a suitable set of parameters obtained for this material model form the test data. As a result, the feasibility of the established viscoelastic model for PC near Tg was confirmed and this material model can be used in FE analysis for the prediction and improvement of the micro thermal imprint process for pattern replication.
A DC Transformer Based on MMC and Full-Bridge Structure with Control Method
Sheng Cheng,Shuhuai Shi,Fang Zhuo,Feng Wang,Yanlin Zhu,Nan Zhang 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
With the deterioration of environmental problems and the shortage of fossil energy, DC distribution net with convenient access to distributed energy has a bright prospect. To connect DC buses with different voltage level, DC/DC converter becomes the focus of research. This paper focuses on the modulation strategy of dc-dc converter based on the modular multilevel converter (MMC) and Full-bridge, which is suitable for medium-low voltage and high-power transmission. On this structure, a quasi-square wave modulation strategy with voltage conversion ability is adopted to improve the performance of the dc-dc converter. This modulation strategy can flexibly alter the AC voltage peak value and limit the dv/dt on the edge of square wave. Simulation results in MATLAB/Simulink verified the proposed modulation strategy.
이문구,란 슈하이,이수훈,이혜진,성연욱,Lee, Moon-G.,Lan, Shuhuai,Lee, Soo-Hun,Lee, Hye-Jin,Ni, Jun,Sung, Yeon-Wook The Korean Society of Manufacturing Technology Eng 2009 한국공작기계학회지 Vol.18 No.3
Large area micro pattern replication has promising application potential in many areas. Rolling imprint process has been demonstrated as one of the most competitive processes for such micro pattern replication, because it has advantages in low cost, high throughput and high efficiency. In this paper, we developed a prototype of roll-to-flat(R2F) thermal imprint system for large area micro pattern replication process, which is one of the key processes in the fabrication of flexible displays. Experimental tests were conducted to evaluate the feasibility of system and the parameters' effect on the process, such as flat mold temperature, loading pressure and rolling speed. 100mm $\times$ 100mm stainless steel flat mold and commercially available polycarbonate sheets were used for the tests. The experimental results showed that the developed R2F system is suitable for fabrication of various micro devices with micro pattern over large area.
Wang, Feng,Zhu, Tianhua,Zhuo, Fang,Yi, Hao,Shi, Shuhuai The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.5
The distributed maximum power point tracking (DMPPT) concept is widely adopted in photovoltaic systems to avoid mismatch loss. However, the high cost and complexity of DMPPT hinder its further promotion in practice. Based on the concept of DMPPT, this paper presents an integrated submodule level half-bridge stack structure along with an optimal current point tracking (OCPT) control algorithm. In this full power processing integrated solution, the number of power switches and passive components is greatly reduced. On the other hand, only one current sensor and its related AD unit are needed to perform the ideal maximum power generation for all of the PV submodules in any irradiance case. The proposal can totally eliminate different small-scaled mismatch effects in real-word condition and the true maximum power point of each PV submodule can be achieved. As a result, the ideal maximum power output of the whole PV system can be achieved. Compared with current solutions, the proposal further develops the integration level of submodule DMPPT solutions with a lower cost and a smaller size. Moreover, the individual MPPT tracking for all of the submodules are guaranteed.