• Title/Summary/Keyword: Boundary Layer Control

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Sensorless Speed Control of Induction Motor by an Improved Sliding Mode Observer (개선된 슬라이딩 모드 관측기에 의한 유도전동기의 센서리스 속도제어)

  • Jang, Min-Young;Kim, Sang-Kyoon;Kwon, Young-Ahn
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.9
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    • pp.1552-1554
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    • 2008
  • Recently, sensorless induction motor drives have been much studied due to several advantages. Sensorless drives eliminate the additional mounting space, increase the reliability in harsh environments, and reduce the cost of a motor. This paper investigates an improved sliding mode observer for the sensorless speed control of an induction motor. The proposed control strategy is the sliding mode observer with a variable boundary layer for a low-chattering and fast-response control. The proposed sensorless-algorithm is verified through the simulation and experimentation.

Sensorless Speed Control of Permanent Magnet Synchronous Motor by an Improved Sliding Mode Observer (개선된 슬라이딩 모드 관측기에 의한 영구자석 동기전동기의 센서리스 속도제어)

  • Kim Young-Sam;Ryu Sung-Lay;Kwon Young-Ahn
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.53 no.11
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    • pp.687-690
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    • 2004
  • Many studies have been performed for the elimination of speed and position sensors which require the additional mounting space, reduce the reliability in harsh environments and increase the cost of a motor. This paper investigates an improved sliding mode observer for the sensorless speed control of a permanent magnet synchronous motor. The proposed control strategy is the sliding mode observer with a variable boundary layer for a low-chattering and fast-response control. The proposed algorithm is verified through the simulation and experimentation.

Dynamic Boundary Tracking Control in Active Sensor Network (동적 센서네트워크에서의 유동적 경계선 추종 제어)

  • Jang, Seyong;Lee, Giroung;Song, Bongsob;Chwa, Dongkyoung;Hong, Sukkyo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.9
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    • pp.1628-1635
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    • 2008
  • In this paper, the motion coordination algorithm of mobile agents in active sensor network is proposed to track the dynamic boundary for environmental monitoring. While most of dynamic boundary tracking algorithms in the literature were studied under the assumption that the boundary and/or its evolving rate is known a priori, the proposed algorithm is assumed that the individual active agent can measure the state of environment locally without any information of the boundary. When the boundary is evolving dynamically, the formation of active agents is designed to achieve two objectives. One is to track boundary layer based on the measured information and a small deviation. The other is to maintain a uniform distance between adjacent agents. The algorithm structure based on a state diagram is proposed to achieve these two objectives. Finally, it will be shown in the simulations that all given agents converge to a desired boundary layer and maintain a formation along the boundary. (e.g., a circle, an ellipse, a triangle and a rectangle)

Modification of Turbulent Boundary Layer Flow by Local Wall Vibration (국소 벽면 진동에 의한 난류경계층 유동 변화)

  • Kim, Chul-Kyu;Jeon, Woo-Pyung;Park, Jin-Il;Kim, Dong-Joo;Choi, Haecheon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.24 no.9
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    • pp.1255-1263
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    • 2000
  • In this study, the modification of turbulent boundary layer flow by local wall vibration is investigated. The wall is locally vibrated using a wall deformation actuator, which moves up and down at the frequencies of 100Hz and 50Hz. Simultaneous measurements of the streamwise velocities in the spanwise direction are performed at several wall-normal and streamwise locations using an in-house multi-channel hot wire anemometer and a spanwise hot-wire-probe rake. The mean velocity is reduced in most places due to the wall vibration and its reduced amount becomes small as flow goes downstream. Interestingly, the mean velocity is found to increase very near the wall and near the actuator. This is due to the motion induced by the streamwise vortices which are generated by the downward motion of the actuator. In case of the streamwise velocity fluctuations, their magnitude increases as compared to the unperturbed turbulent boundary layer, and the increased amount becomes small as the flow moves downstream. The modified flow field at the forcing frequency of 50Hz is not much different from that of 100Hz, except the reduced amount of modification.

Digital variable structure control of a hot-water heating control system with long dead time (긴 지연시간을 갖는 온수난방 제어시스템의 디지틀 가변구조제어)

  • 안병천;장효환
    • 제어로봇시스템학회:학술대회논문집
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    • 1991.10a
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    • pp.232-237
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    • 1991
  • Digital Variable Structure Controller(DVSC) is proposed to control variable speed recirculating pump for hot-water heating control system. In this study, nonlinear sliding line is used beyond output error boundary layer and PID sliding line is used within the layer. For long dead time compensation, constraint is added to Smith predictor algorithm. Steady state error is eliminated by using the proposed sliding line in spite of heating load change. By decreasing sampling time, good sliding motion is yielded but system output noise bv flow dynamics is amplified.

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Plume Interference Effect on a Missile Body and Its Control (미사일 동체에서 발생하는 Plume 간섭 효과와 제어)

  • Lim, Chae-Min;Lee, Young-Ki;Kim, Heuy-Dong;Szwaba, Ryszard
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.1730-1735
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    • 2003
  • The plume-induced shock wave is a complex phenomenon, consisting of plume-induced boundary layer separation, separated shear layer, multiple shock waves, and their interactions. The knowledge base of plume interference effect on powered missiles and flight vehicles is not yet adequate to get an overall insight of the flow physics. Computational studies are performed to better understand the flow physics of the plume-induced shock and separation particularly at high plume to exit pressure ratio. Test model configurations are a simplified missile model and two rounded and porous afterbodies to simulate moderately and highly underexpanded exhaust plumes at the transonic/supersonic speeds. The result shows that the rounded afterbody and porous wall attached at the missile base can alleviate the plume-induced shock wave phenomenon, and improve the control of the missile body.

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Turbulent boundary layer control via electro-magnetic forces (전자기력을 이용한 난류경계층 제어)

  • Lee J.-H.;Sung H, J.
    • 한국전산유체공학회:학술대회논문집
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    • 2004.03a
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    • pp.166-171
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    • 2004
  • Direct numerical simulations are peformed to investigate the physics of a spatially developing turbulent boundary layer flow suddenly subjected to spanwise oscillating electro-magnetic forces in the near-wall region. The Reynolds number based on the inlet momentum thickness and free-stream velocity is $Re_\theta=300$. A fully-implicit fractional step method is employed to simulate the flow. The mean flow properties and the Reynolds stresses are obtained to analyze the near-wall turbulent structure. It is found that skin-friction and turbulent kinetic energy can be reduced by the electro-magnetic forces. Instantaneous flow visualization techniques are used to observe the response of streamwise vortices to spanwise oscillating forces. The near-wall vortical structures are clearly affected by spanwise oscillating electro-magnetic forces.

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Computational Study of the Passive Control of the Oblique-Shock-Interaction Flows (경사충격파 간섭유동의 피동제어에 관한 수치해석적 연구)

  • Chang, Sung-Ha;Lee, Yeol;Lee, Yong-Hee
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2006.11a
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    • pp.327-330
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    • 2006
  • Numerical study on the passive control of the oblique shock wave/turbulent boundary-layer interaction control utilizing slotted plates over a cavity has been carried out. Numerical results have been compared with the experimental observations, such as pitot/wall surface pressures and Schlieren flow visualizations, obtained for the same boundary conditions. It was found that the present numerical results shows a good agreement with experimental data. Further, the effect of different slot configurations including various number, location and angle of slots on the characteristics of the interactions are also tested, focusing on the variation of the piot pressure and the boundary-layer characteristics downstream of the interaction and the recirculating mass flux through cavity.

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A Study on the High Efficiency PR Strip technology by using the Ozone Process (오존공정을 이용한 고효율 PR 제거기술 연구)

  • Son, Young-Su
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.44 no.1
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    • pp.22-27
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    • 2007
  • we have been studied on the realization of the boundary layer controlled ozone process and related facilities in order to apply for the photo-resist strip process in the semiconductor and flat panel display manufacturing. By means of developing the technology for the high concentration ozone production, it was possible to realized the boundary layer control ozone process by vapor. As a result of the silicon wafer PR strip test, we obtained the strip rate of about 400nm/min at the ozone concentration of 16wt% and flow rate of 8[liter/min.].

Tracking Control of Variable Structure System with a New Variable Boundary Layer (새로운 가변 경계층을 갖는 가변 구조 제어 시스템의 추적 제어)

  • Lee, Hui-Jin;Kim, Eun-Tae;Kim, Dong-Yeon
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.37 no.3
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    • pp.19-32
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    • 2000
  • This paper suggests the variable structure controller with a new variable boundary layer for the accurate tracking control of the variable structure systems. Up to now, variable structure controller (VSC) applying the variable boundary layer did not remove chattering from an arbitrary initial state of the system trajectory because VSC has the limited initial state according to the fixed sliding surface. But, by using the linear time-varying sliding surfaces, the scheme has the robustness against chattering from all states. The suggested method can be applied to the second-order nonlinear systems with parameter uncertainty and extraneous disturbances, and has better tracking performance than the conventional method. To demonstrate the advantages of the proposed algorithm, it is applied to a two-link manipulator.

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