• 신재생에너지
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• 제7권4호
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• pp.58-65
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• 2011

In variable-speed variable-pitch wind turbines, the conventional approach for controlling power-production operation relies on a generator-torque controller and a rotor-collective blade-pitch controller. Both controllers use the generator speed measurement as the sole feedback input. In order to mitigate unwanted excitation of the control system, many filters are adopted. In this study, the characteristics of some filters for signal processing are investigated based on frequency response function. They include low-pass filters, band-pass filters, and notch filters. Especially, this study focuses on design parameters of their filters.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.36.2-36.2
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• 2011

In variable-speed variable-pitch wind turbines, the conventional approach for controlling power-production operation relies on a generator-torque controller and a rotor-collective blade-pitch controller. Both controllers use the generator speed measurement as the sole feedback input. In order to mitigate unwanted excitation of the control system, many filters are adopted. In this study, the characteristics of some filters for signal processing are investigated based on frequency response function. They include low-pass filters, band-pass filters, and notch filters. Especially, this study focuses on design parameters of their filters.

• 유공압시스템학회논문집
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• 제7권4호
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• pp.32-38
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• 2010

A semi-active suspension is an automotive technology that controls the vertical movement of the vehicle while the car is driving. The system therefore virtually eliminates body roll and pitch variation in many driving situations including cornering, accelerating, and braking. This technology allows car manufacturers to achieve a higher degree of both ride quality and car handling by keeping the tires perpendicular to the road in corners, allowing for much higher levels of grip and control. An onboard computer detects body movement from sensors located throughout the vehicle and, using data calculated by opportune control techniques, controls the action of the suspension. Semi-active systems can change the viscous damping coefficient of the shock absorber, and do not add energy to the suspension system. Though limited in their intervention (for example, the control force can never have different direction than that of the current speed of the suspension), semi-active suspensions are less expensive to design and consume far less energy. In recent time, the research in semi-active suspensions has continued to advance with respect to their capabilities, narrowing the gap between semi-active and fully active suspension systems. In this paper we are studied the characteristics of vehicle movement during the field test with conventional and semi-active suspension system.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.30-35
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• 2010

The railway vehicle is a multi-body system running on the track which consists of carbody, bogie and wheelset, each of components is connected with rigid mass, spring and damper. each of components has translation motions of longitudinal (X axis), lateral(Y axis) and vertical(Z axis) direction, and rotation motions of X, Y, Z axis which are named Rolling, Pitching and Yawing. The vibration mode of railway vehicle is difficult to find the characteristics of motion during the operation on the track because these happen to independence or duplication motion caused by vehicle, wheel/rail and track irregularity etc. This paper presents the result of ramp test to show the bounce, roll, pitch and yaw mode frequency of the railway vehicle.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.105-105
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• 2000

In this paper, an integrated control of the semi-active suspension system using a reduced full-car model is investigated. By including the reduced full-car dynamics in the control law, the semi-act ive suspension system is able to control not only the vertical acceleration but also the roll and pitch mot ions of the car body, which is not Possible with a quarter-car model or a half-car model. The damping forces for the semi-active dampers are designed to track the damping forces of the skyhook controller designed from the reduced full car dynamics. Computer simulations and experimental results using a real car are also included.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.52-56
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• 2011

Recently, KARI(Korea Aerospace Research Institute) has been developing a modern 11.5m diameter four bladed bearingless main rotor system, and this rotor system can be used for 7,000lb class helicopter. Flexbeam and torque tube can be considered as the key structural components, and large elastic twist of flexbeam induced by pitch control motion of torque tube can influence the nonlinear aeroelastic behavior. In this paper, the dynamic characteristic analysis results of bearingless rotor system were presented. In order to construct a input model and validate the analysis procedures, calculated results using the comprehensive helicopter analysis program CAMRAD II were compared with the measured natural frequencies and lag damping data from small-scale wind tunnel test. Next, the analysis model was extended to a full-scale model, and the dynamic analysis results were presented.

• 한국소음진동공학회논문집
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• 제22권2호
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• pp.187-192
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• 2012

Recently, KARI(Korea Aerospace Research Institute) has been developing a modern 11.5 m diameter four bladed bearingless main rotor system, and this rotor system can be used for 7,000 lb class helicopter. Flexbeam and torque tube can be considered as key structural components, and large elastic twist of flexbeam induced by pitch control motion of torque tube can influence the nonlinear aeroelastic behavior. In this paper, the dynamic characteristic analysis results of bearingless rotor system were presented. In order to construct a input model and validate the analysis procedures, calculated results using the comprehensive helicopter analysis program CAMRAD II were compared with the measured natural frequencies and lag damping data from small-scale wind tunnel test. Next, the analysis model was extended to a full-scale model, and the dynamic analysis results were presented.

• 한국태양에너지학회 논문집
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• 제36권6호
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• pp.1-12
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• 2016

A control algorithm for a 100 kW wind turbine is designed in this study. The wind turbine is operating as a variable speed variable pitch (VSVP) status. Also, this wind turbine is a permanent magnet synchronous generator (PMSG) Type. For the medium capacity wind turbine considered in this study, it was found that the optimum tip speed ratios to achieve the maximum power coefficients varied with wind speeds. Therefore a commercial blade element momentum theory and multi-body dynamics based program was implemented to consider the variation of aerodynamic coefficients with respect to Reynolds numbers and to find out the power and thrust coefficients with respect tip speed ratio and blade pitch angles. In the end a basic power controller was designed for below rated, transition and above rated regions, and a load reduction algorithm was designed to reduce tower vibration by the nacelle motion. As a result, damage equivalent Load (DEL) of tower fore-aft has been reduced by 32%. From dynamic simulations in the commercial program, the controller was found to work properly as designed. Experimental validation of the control algorithm will be done in the future.

• 한국항공우주학회지
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• 제44권5호
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• pp.439-446
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• 2016

이 논문에서는 무베어링 로터의 동특성을 비회전 강성 및 진동수 측정 시험과 회전 훨타워 시험을 통해 살펴보았다. 무베어링 로터의 주요 구성품인 블레이드, 유연보, 토크튜브에 대해 강성 및 고유진동수를 측정하여 해석을 위한 물성치를 확보하였고, 훨타워 시험 전에 댐퍼와 스너버를 장착한 무베어링 로터를 조립하여 지상에서 하중이 부가되는 조건하에 기능시험을 수행하여 로터 구성품간의 간섭 여부, 기구학적 거동 등을 확인하였다. 4개의 블레이드를 가지고 회전반경이 5.82m인 무베어링 로터의 회전 동특성시험을 회전면 높이가 9.65m인 훨타워에서 수행하였다. 정지비행성능을 확인하기 위해 추력과 사용동력을 측정하였으며, 회전시 블레이드의 고유진동수 및 감쇠를 측정하기 위해 유압 가진기를 통하여 사이클릭 가진을 하였다.

• Ocean Systems Engineering
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• 제3권3호
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• pp.203-217
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• 2013

A PTO (power-take-off) mechanism by using relative heave motions between a floating buoy and its inner mass (magnet or amateur) is suggested. The inner power take-off system is characterized by a mass with linear stiffness and damping. A vertical truncated cylinder is selected as a buoy and a special station-keeping system is proposed to minimize pitch motions while not affecting heave motions. By numerical examples, it is seen that the maximum power can actually be obtained at the optimal spring and damper condition, as predicted by the developed WEC(wave energy converter) theory. Then, based on the developed theory, several design strategies are proposed to further enhance the maximum PTO, which includes the intentional mismatching among heave natural frequency of the buoy, natural frequency of the inner dynamic system, and peak frequency of input wave spectrum. By using the intentional mismatching strategy, the generated power is actually increased and the required damping value is significantly reduced, which is a big advantage in designing the proposed WEC with practical inner LEG (linear electric generator) system.