• Steel and Composite Structures
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• 제36권2호
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• pp.179-186
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• 2020

In this paper, the forced resonance vibration of porous functionally graded (FG) curved nanobeam is examined. In order to capture the hardening and softening mechanisms of nanostructure, the nonlocal strain gradient theory is employed to build the size-dependent model. Using the Timoshenko beam theory together with the Hamilton principle, the equations of motion for the curved nanobeam are derived. Then, Navier series are used in order to obtain the dynamical deflections of the porous FG curved nanobeam with simply-supported ends. It is found that the resonance position of the nanobeam is very sensitive to the nonlocal and strain gradient parameters, material variation, porosity coefficient, as well as geometrical conditions. The results indicate that the resonance position is postponed by increasing the strain gradient parameter, while the nonlocal parameter has the opposite effect on the results. Furthermore, increasing the opening angle or length-to-thickness ratio will result in resonance position moves to lower-load frequency.

• 조명전기설비학회논문지
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• 제24권4호
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• pp.185-191
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• 2010

본 논문에서는 인덕턱스의 변화에 따른 전류 변화율을 모니터링 하여 회전자의 속도 및 위치를 추정하는 센서리스 구동방법을 제안한다. 전류의 변화율은 히스테리시스 전류제어 방법을 이용하여 인접한 두 스위치 온 타임을 비교함으로써 간단히 측정할 수 있다. 제안된 방법은 복잡한 계산이나 별도의 하드웨어를 필요치 않으므로 구현이 용이하다. 시뮬레이션과 실험 결과는 제안한 방법의 실효성을 보여준다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(2)
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• pp.972-975
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• 2004

This paper presents a simulation results of sensorless control of Switched Reluctance Motor(SRM) using neural network. The basic algorithm of this scheme is based on the flux linkage characteristic according to the phase current and the rotor position. A sufficient simulation data was used for neural network training. Through measurement of the phase flux linkage and phase currents the neural network is able to estimate the rotor position. The simulation result shows some good results, and possibility of this algorithm.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.1154-1156
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• 2001

This paper presents the implementation of a positon sensorless vector control system of a PM linear synchronous motor by sliding mode observer based on TMS320F240 DSP controller. Sliding mode observer estimates the secondary velocity and position based on the measurement of current, and it shows very robust characteristic to parameter variation. Therefore, it improves the system performance deterioration caused by system parameter variations. Simulation and experimental considerations are presented to confirm the applicability of sliding mode observer to the sensorless position control of PMLSM.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
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• pp.145-147
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• 1993

This paper described an optimal control technique for position control of an inverter-fed PMSM drive. A control system of PM machine for position, speed and current control based on optimal sliding mode control system is discussed. This is an effective means to keep a system insensitive to parameter variation, disturbance and chattering reduction. The main purpose of the control is to improve the dynamic response of the PMSM with the load of the inertial plant. The optimal sliding mode control strategy is analyzed and the performance is investigated by the computer simulation using actual parameters of a drive system, Simulation results are given and discussed.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.607-612
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• 1992

This paper presents a tip position control of a single-link flexible arm with a payload by using closed loop control. The shifting problem of the arm from the initial position to desired position is considered by the variation of the displacement gain $G_{p}$ and velocity gain $G_{v}$. The system is composed of a flexible arm with payload, DC servomotor, and a ballscrew mechanism. The flexible arm is mounted on a mobile stage driven by a servomotor and ballscrew. As a result, the increase of the displacement and velocity gain respectively comes to the reduction of tip vibration. Theoretical results are approximately in good agreement with those obtained experimentally.y.y.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1992년도 춘계학술대회 논문집
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• pp.185-189
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• 1992

This paper prsents an end-point control of a one-link flexible arm with a payload by using closed loop control. Tip position of arm is shifted by the base motion according to DC servomotor, whivh is driven by a feedback signal composed of the tip displacement and the estimated tip velocity. The shifting problem of the arm from initial position to desired position is considered by the variation of the displacement gain Gd and velocity agin Gv. Theoretical results are obtained by applying the method of the Laplace transform to the governing equations and the method of numerical inversion. This system is composed of a flexible arm with payload, DC servomotor, and a ballscrew mechanism. The flexible arm is mounted on a mobile stage driven by a servomotor and ballscrew. In controlling the tip displacement of flexible arm, the fundamental bode vibration is supressed more rapidly with an increase of the velocity feedback gain Gv and the feedback displacemenmt gain Gd. Theretical responses are approximately in good agreement with those obtained experimentally.

• 산업기술연구
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• 제20권B호
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• pp.45-53
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• 2000

A numerical study is done on the thrust vector control using gaseous secondary injection in the rocket nozzle. A commercial code, PHOENICS, is used to simulate the rocket nozzle flow. A $45^{\circ}-15^{\circ}$ conical nozzle is adopted to do numerical experiments. The flow in a rocket nozzle is assumed a steady, compressible, viscous flow. The exhaust gas of the rocket motor is used as an injectant to control the thrust vector of rocket at the constant rate of secondary injection flow. The injection location which is on the wall of rocket is chosen as a primary numerical variable. Computational results say that if the injection position is too close to nozzle throat, the reflected shock occurs. On the other hand, the more mass flow rate of injection is needed to get enough side thrust when the injection position is moved too far from the throat.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권10호
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• pp.646-651
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• 2000

Recently, the 2-phase brushless DC motor has been used in electric home appliance for low price and low energy consumption. In this paper, we analyzed a 2-phase BLDC motor using time-step finite element method. And the validity of analysis is confirmed by measuring the flux distribution on the surface of permanent magnet and back-EMF. As well, we have calculated the dynamic characteristics of target motor considering the Hall sensor position. So, we have found the optimum switching position, and improved performance of 2-phase BLDC motor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.1041-1043
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• 1993

A robust position control scheme for a Brushless Direct Drive Motor(BLDDM) is presented. To obtain the robustness under the load variation, a Variable Structure Controller(VSC) is used. However, the VSC has a chattering problem and require the full state informations. To overcome this problem, in this paper, the sliding mode observer is used for compensating the load disturbance and estimating the motor velocity. As a result, the VSC for a BLDDM posision control is designed by using only position measurment and the chattering problem is greatly reduced. To show the validaty of the proposed scheme, the simulation study is carried out.