• Journal of Institute of Control, Robotics and Systems
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• v.15 no.12
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• pp.1157-1162
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• 2009

The aerodynamic torque and power caused by the interaction between the wind and blade of wind turbine are highly nonlinear. For this reason, the overall dynamic behaviors of wind turbine have nonlinear characteristics. The aerodynamic nonlinearity also affects properties of torque control for wind turbine. In this paper, the nonlinear aerodynamic property according to the wind speed below rated power and its effects on the torque control system are investigated. Nonlinear parameter representing change of aerodynamic torque with respect to rotor speed is obtained by linearization technique. Effects of this aerodynamic nonlinear parameter on the closed-loop torque system with PI controller for an 1.5 MW wind turbine are presented.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.916-917
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• 2015

This paper deals with electromagneitc characteristics analysis of high-speed brushless DC motor. First, under same rated and restricted conditions, four models which have different slot combinations each other are designed using 2-d finite element (FE) analyses. Designed models are analyzed and compared in terms of core loss, copper loss, eddy-current loss, etc. On the basis of analysis results, it is found that the motor with a 2-pole PM rotor and a 6-slot stator has most outstanding performances in electromagnetic aspects.

• The KSFM Journal of Fluid Machinery
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• v.20 no.1
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• pp.48-52
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• 2017

Small-scale motor-generator sets have been used in laboratories for verification of real large wind turbines whose rated power are more than 1 MW. In this paper, a result of designing a small-scale motor-generator system, which is composed of motor, gear box, flywheel, and generator, is presented in the aspect of speed response. Design objective is to make a small-scale motor-generator system have the same time constant and optimal tip speed ratio region as a real MW wind turbine. A small-scale 3.5 kW motor-generator system for emulating response of a 2 MW wind turbine is considered and designed.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.3
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• pp.183-188
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• 2014

Power conversion systems used in large gas turbine power plant can be divided into two main part. Because of the initial start-up characteristic of the gas turbine combustor, the gas turbine must be accelerated by starting device(LCI : Load Commutated Inverter) up to 10%~20% of rated speed to ignite it. In addition, the ECS(Excitation Control system) is used to control the rotor field current and reactive power in grid-connected synchronous generator. These two large power conversion systems are located in the same space(container) because of coordination control. Recently, many manufactures develop high speed controller based on function block available in the LCI and ECS with the newest power semiconductor. We also developed high speed controller based on function block to be using these two system and it meets the international standard IEC61131 as using real-time OS(VxWorks) and ISaGRAF. In order to install easily these systems at power plant, main controller, special module and IO module are used with high speed communication line other than electric wire line. Before initial product is installed on the site, prototype is produced and tests are conducted for it. The performance results of Integrated controller and application program(SFC, ECS) were described in this paper. The test results will be considered as the important resources for the application in future.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.347-349
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• 1995

This paper describes current controlled PWM technique of IPM synchronous motors for a wide variety of speed control applications. They are however limited in their ability to operate in the power limited regime where the available torque is reduced as the speed is increased above its base value. This paper reviews the operation of the IPMSM drives when they are constrained to be within the permissible envelope of maximum inverter voltage and current to produce the rated power and to provide this with the highest attainable rotor speed. This paper proposes a new field-weakening control algorithm using phase current feedback to improve the torque characteristics and to reduce the torque ripple of IPMSM in the constant power region. The improved torque characteristics of speed control strategy with current feedback control algorithm is analyzed and the performance is investigated by the computer simulation results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.92-99
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• 2016

A wind turbine is controlled for the purpose of obtaining the maximum power below its rated wind speed. Among the methods of obtaining the maximum power, TSR (Tip Speed Ratio) optimal control and P&O (Perturbation and Observation) control are widely used. The P&O control algorithm using the turbine power and rotational speed is simple, but its slow response is a weak point. Whereas TSR control's response is fast, it requires the precise wind speed. A method of measuring or estimating the wind speed is used to obtain a precise value. However, estimation methods are mostly used, because it is difficult to avoid the blade interference when measuring the wind speed near the blades. Neural networks and various numerical methods have been applied for estimating the wind speed, because it involves an inverse problem. However, estimating the wind speed is still a difficult problem, even with these methods. In this paper, a new method is introduced to estimate the wind speed in the wind-power graph by using the turbine power and rotational speed. Matlab/Simulink is used to confirm that the proposed method can estimate the wind speed properly to obtain the maximum power.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.4_2
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• pp.533-540
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• 2022

This paper is the research result of designing and developing a BLDC motor for driving a condenser fan, which is widely used in air conditioners of commercial vehicles and specially equipped vehicles, and produced with a target value. The design of the motor was carried out in the order of designing the electric and magnetic circuits after determining the motor specifications. The process was repeated with different set values until the designed target condition was satisfied, and the electric and magnetic field distributions were made to be equal by reflecting the characteristics of the material. As a structural feature of the motor, it is a rotating field type composed of multipoles, and has a structure in which a permanent magnet is attached to the surface of the rotor. The manufactured BLDC motor is a 3-phase square wave driving method, with a rated voltage of 24 [V], a rotational speed of 2,500 [rpm], a rated current of 10 [A], and a power consumption of 180 [W]. A microcontroller for driving and controlling the motor was also manufactured.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.835-842
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• 2014

Cutback control in a grid code is one of the functions of a wind power plant (WPP) that is required to support the system protection and frequency stability. When a cutback control command signal is delivered to the WPP from the system operator, the output of a WPP should be decreased to 20% of the rated power within 5 s. In this paper, we propose a dedicated cutback control algorithm of a WPP based on the ratio of the command power to the available power. If a cutback control signal is delivered, the algorithm determines the pitch angle for the cutback control and starts the pitch angle control. The proposed algorithm keeps the rotor speed at the speed before the start of the cutback control to quickly recover the previous output prior to the cutback control. The performance of the algorithm was validated for a 100 MW aggregated WPP based on a permanent magnet synchronous generator under various wind conditions using an EMTP-RV simulator. The results clearly shows that the proposed algorithm not only successfully reduces the output to the command power within 5 s by minimizing the fluctuation of the pitch angle, but also rapidly recovers to the output level before the cutback control.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.3
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• pp.349-357
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• 2014

The performance of a Synchronous Reluctance Motor (SynRM) in terms of torque and power factor depends on the two-axis inductances $L_d$ and $L_q$ of the machine. The Axially Laminated Anisotropic (ALA) rotor should be proposed in an effort to increase the $L_d/L_q$ ratio and the $L_d-L_q$ difference to secure high torque density and high power factor. So, ALA rotor is suitable for high speed instruments. This paper deals with optimum design of Axially Laminated Anisotropic Synchronous Reluctance Motor (ALA-SynRM) and comparison of characteristics with induction motor. Coupled Finite Element Methodology (FEM) & Response Surface Methodology (RSM) have been used to evaluate optimum design solutions. Comparisons are given with characteristics of a same rated wattage induction motor and those of ALA-SynRM respectively.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.632-635
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• 2009

Nowadays renewable energy has undergone major development, however most renewable energy resources still have demerit which is under the influence of environmental factors that can not be set up the power plants or can not be generated the rated power. To wander from the point of environmental instability, the present paper looks at the tidal current energy which can supply regular electric power. It has an important merit which is more predictable than others, however the place which can be set up is limited and the turbine system must be optimized. The development of the optimized rotor blades design is urgent to obtain regular electric power using the tidal current energy. Therefore, the paper expands on this idea and presents a conceptual design of 100kW horizontal axis rotor blade for the tidal current turbine using blade element momentum (BEM) analysis. The compatibility of horizontal axis tidal turbine (HATT) is verified using a commercial computational fluid dynamics (CFD) code, ANSYS-CFX. This paper presents results of the numerical analysis, such as pressure, streak line and the performance curves with torque data for the inflow of the horizontal axis tidal current turbine (HATT).