• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.1
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• pp.59-65
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• 2011

The aerodynamic power and torque of wind turbines are extremely nonlinear. Therefore, the overall dynamic behavior of a wind turbine exhibits nonlinear characteristics that are dependent on the magnitude of the wind speed. The nonlinear aerodynamic characteristics of the wind turbine also affect the characteristics of the control system of the wind turbine. Therefore, the analysis of the nonlinear aerodynamic characteristics of wind turbine is essential in designing the wind-turbine controller. In this study, the nonlinear aerodynamic characteristics and the effects of these characteristics on the closed-loop pitch system with PI controller for an 1-mass model of the wind turbine are investigated above rated power.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.3
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• pp.200-209
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• 2013

In this paper, the types of B-dot controller and the review results of B-dot controller stability are summarized. Also, it is confirmed that B-dot controller is very useful and essential tool when a dawn-dusk low earth orbit(LEO) large satellite has especially to capture the Sun for a required power supply in a reliable way after anomaly and that its algorithm is very simple for on-board implementation. New physical interpretation of B-dot controller is presented as a result of extensive theoretical investigation introducing the concept of transient control torque and steady state control torque. Also, the failure effect analysis results of magnetic torquers as well as a simulation verification are included. And the design recommendation for optimal design is provided to cope with the failure of magnetic torquer. Nonlinear simulation results are included to justify its capability as well as its performance for an application to a dawn-dusk LEO large satellite.

• Journal of IKEEE
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• v.24 no.4
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• pp.1104-1108
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• 2020

This paper propose a variable proportional resonant feedforward algorithm for reducing the speed ripple of a three-phase permanent magnet synchronous motor. In general, the torque ripples can be generated by electrical pulsation due to current measurement errors and dead time and mechanical pulsation because of rotor eccentricity and eccentric load. These torque pulsations can cause speed pulsations of the motor and degrade the operating performance of the motor drive system. Therefore, in this paper, the factors of the speed ripple is analyzed and an algorithm to reduce the speed ripple is proposed. The proposed algorithm applied a variable proportional resonant controller in order to reduce the specific operating frequency included in the speed pulsation, and utilized a feedforward compensation controller structure to perform the compensation operation. The proposed algorithm is verified through various experiments.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.1507-1510
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• 2012

본 논문은 EPS(전자식 파워 스티어링)에 사용되는 Torque and Angle sensor 의 절대각 신뢰성 보증 방식에 관한 것으로, Inductive 방식의 센서에서 절대각 신호 신뢰성 보증에 대한 효과적인 방법을 제시한다. 전동식 파워 스티어링 시스템의 ECU(전자제어유닛)는 조타각도를 출력하는 2 개의 소자에서 버니어 알고리즘을 통해 360 도 이상의 멀티 조타각을 인식하게 된다. 토크&조향각 센서는 절대 조향각을 계산하는 1 개의 Hall IC 소자 신호와, 상대 조향각을 계산하는 ASIC 소자 신호를 사용하여 멀티 조타각을 인식한다. 인식된 조타각이 추가적인 검증 절차 없이 제어에 사용된다면, 센서의 이상 발생 시에 운전자의 조타감을 불편해질 수 있고, 나아가서는 차량사고의 위험을 발생시킬 수 있다.따라서 차량 거동 시 절대 조향각의 신뢰성 검증은 제어와 동시에 항상 요구되어야 한다. 특히, 유럽/미국 업계의 ISO 26262 표준 도입에 따라 절대 조향각의 높은 신뢰성이 요구된다. 본 논문에서는 이러한 요구사항을 만족하기 위해 측정된 절대각 신호를 기준으로 상대각 신호 2 개를 측정에 사용하고, Driving 시에도 절대각 기준의 신뢰도 향상을 위해 절대각 신호 1 개를 비교기로 사용한다. 최적화된 에러 기준을 근거로 절대 조향각 신호의 신뢰성을 보장하는 방법을 제안한다. 이러한 방법을 적용한다면, 정확하고 안정적으로 조타각을 결정함으로써 EPS 안전성 확보에 도움을 줄 수 있다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.12
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• pp.1359-1365
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• 2014

In this study, 1-way fluid structure interaction analysis(FSI) for the shutter, component of side jet thruster was performed to evaluate the safety. Driving torque to open nozzle, thermal and high pressure load of hot gas was applied to shutter. Thus, the shutter must be designed to endure this load during combustion. We carried out computational fluid dynamics analysis to obtain the pressure, temperature, and heat transfer coefficient of hot gas of side jet thruster. We then used the data as the load condition for a thermal structural analysis using a mapping method. The locations with the maximum stress and temperature distributions were found. We compared the maximum stress with the tensile stress of shutter material according to temperature to evaluate the safety. We also analyzed the radial deformation of the shutter to set the proper interface gap with the side jet thruster parts.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.149-153
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• 2003

AC 부하를 갖는 동기전동기에 있어서, 동기전동기의 속도리플을 저감시키기 위한 문제를 풀기위해 3가지 제어기법에 대해 비교를 한 후 가장 강인한 제어기법에 대해 분석하였다. AC 부하를 갖는 특별한 제어 대상으로 엑스선 전산화 단층촬영 장치(CT)용 겐트리를 선정하였으며 시스템이 갖는 특별한 구조에 의해 이러한 시스템 특성을 갖는다. 동기전동기의 출력 축에 링(Fing) 모양의 원판 프레임을 갖으며, 이 원판 표면에 무게가 서로 다른 여러 장치(X_선 튜브, X-선 검출기, 고압발생장치, DAS 장치, 온도조절장치 등)를 부착하여 영상 획득 시스템의 회전부를 구축하기 때문이다. 이러한 시스템에서는 무게 평형을 갖지 못하는 편심 무게가 존재하게 되며 이로써 전동기 관점에서는 AC 부하처럼 인식되는 제어 조건으로 인식 될 수 있다. AC 부하를 갖는 동기전동기에 대해 일반적인 벡터제어 알고리즘으로 제어를 수행하면 정상상태에서도 속도 오차가 "0" 으로 줄어들지 않고 AC 형태의 오차 성분이 존재하며 편심 무게의 크기에 비례하여 진폭이 커지는 특성을 갖는다. 이러한 문제점을 해결하기 위하여 Sine파 보상전류를 갖는 속도제어기법, 펀심부하토크 관측기를 이용한 속도제어기법, 그리고 기준모델제어기법을 소개하였다. 각 방법에 대한 실험 결과로부터 편심무게의 변동과 편심 위치의 변동 조건에서 기준모델제어기법이 강인한 제어 특성과 리플저감 측면에서 가장 우수함을 검증하였다. 이로써 AC 부하 조건에서 고정도 속도 제어기가 요구되는 경우 좋은 선택의 지침이 될 수 있다고 본다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.363-368
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• 2013

This paper relates to the electric braking, the permanent magnet synchronous motor vector control is suspended until the applied, and propose a new scheme by the controller in the observer to estimate the position and velocity using the Resolver speed detector. In addition, as a way to control the speed by braking torque at low speed, the pole of a stop just before the stop electrical braking. As a result, noise and dust abatement, consumption, reduction of the brake shoe increase the maintainability of comfort and energy use, enhances the effect of EMU performance improved sikyeoteum could see.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.4
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• pp.69-77
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• 2012

We propose a PLL-type position control method for step motors. Our control method considerably improves the instability problem at rapid acceleration or deceleration, which is a major problem of conventional open loop control methods. Moreover, our controller reduces the steady state position error to zero and guarantees lower vibration and acoustic noise at high speed. Also, our controller can produce more torque at high speed, and hence it can extend the controllable velocity range. To demonstrate the practical significance of our control method, we present some simulation results for a commercially available step motor using Simulink.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.2
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• pp.317-326
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• 2008

This paper presents a vector control implementation for SPMSM(Surface-mounted Permanent Magnet Synchronous Motor) using dSPACE 1104 system and MATLAB/SIMULINK. SPMSM can be treated as a DC motor provided that currents of flux and torque component are controlled independently using vector control. Therefore various control algorithms for conventional DC motor control can be adopted to SPMSM. The system is designed to improve set-point tracking capability, fast response, and accuracy In This paper, d-q equivalent modeling of PMSM is derived based on vector control theory. PI controller is used for speed control and decoupling PI controller is used for current control. For the implementation of high performance vector control system, dSPACE 1104 system is used. Experiments were carried out to examine validity of the proposed vector control implementation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.281-284
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• 2006

An intelligent performance diagnostic program using the Neural Network was proposed for PW206C turboshaft engine. It was selected as a power plant for the tilt rotor type Smart UAV (Unmanned Aerial Vehicle) which has been developed by KARI (Korea Aerospace Research Institute). The measurement parameters of Smart UAV propulsion system are gas generator rotational speed, power turbine rotational speed, exhaust gas temperature and torque. But two measurement such as compressor exit pressure and compressor turbine exit temperature were added because they were difficult each component diagnostics using the default measurement parameter. The performance parameters for the estimate of component performance degradation degree are flow capacities and efficiencies for compressor, compressor turbine and power turbine. Database for network learning and test was constructed using a gas turbine performance simulation program. From application results for diagnostics of the PW206C turboshaft engine using the learned networks, it was confirmed that the proposed diagnostics could detect well the single fault types such as compressor fouling and compressor turbine erosion.