• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.319-322
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• 1997

In vector control technique, stator currents of an induction motor are transformed to equivalent d-q currents in reference frame consist of d and q axis, each of which is coincide with flux and torque direction respectively. In this paper, the new algorithm is suggested where the stator current through an induction motor torque is monitored by using a vector control method where an additional equipment is not need. The G-programming is used to apply the suggested algorithm in the experiment and this is applied to an actual system to monitor the torque value of an induction motor on real time. To solve the vibration trouble of estimated torque caused from an unbalanced real rotating speed of an induction motor and measured rotating speed by suggesting the reconstructed in a method based on measurement current signal. This produced system testifies an accuracy of an induction motor through the experiment by comparing the reference value of the control method.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.9
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• pp.40-46
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• 2003

Synchronizing errors between the spindle motor and the z-axis motor directly influences the cutting characteristics and the thread quality in tapping, because the tapping process is accomplished by synchronizing the movement of the z-axis with the revolutionary spindle motion. Generally synchronizing errors are decided by tile parameters of the servo system and commanded velocity. The excessive synchronizing errors which are induced by the parameter mismatch and high cutting velocity can cause tap breakage due to the abrupt increase of cutting torque or damage the thread accuracy by overcutting the already cut threads. In this paper, the influences of the synchronizing errors on the tapping characteristics in the ultra high-speed tapping will be described and a minimum level of synchronizing errors necessary to maintain the quality of the cut thread will be presented.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.1
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• pp.42-48
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• 2009

A design methodology for control strategy and control structure gives a direct impact on wind turbine's performance and life cycle. A baseline control law which is a variable rotor speed and variable pitch control strategy is introduced, and a mathematic performance model of a wind turbine dynamics is derived. By using a numeric optimization algorithm, the steady state operating conditions of wind turbines are identified. Because aerodynamic interaction of winds with rotor blades is basically nonlinear, a linearization procedure is applied to analyze wind turbine dynamic variations for whole operating conditions. It turns out the wind turbine dynamics vary much depending on its operating condition.

• Journal of Industrial Technology
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• v.35
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• pp.9-13
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• 2015

In this paper, a new excitation scheme is developed to increase the output torque of the sensorless BLDC(Brushless DC) motor(BLDCM), which drives fins to control the flight attitude of a guided artillery munition. The proposed scheme is based on a 12-step excitation strategy combining two-phase and three-phase excitations. The proposed 12-step excitation scheme can produce more torque than a typical 6-step scheme for the start-up and synchronous operation in the sensorless BLDCM drive. The simulation and experimental results on the sensorless BLDCM drive system to control the fin were verified the validity of the proposed scheme.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.2
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• pp.417-423
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• 2012

In this paper, In order to make up for the weak point of driving structure that existing used single motor in motor design, as a method to make use of advantage for joint of hollow type, we propose implementation methods for high torque, high precision, backlash less, and design of secondary safety device, and application method through joint organization using multiple motors.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1054-1056
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• 2008

최근 전기 철도 시스템에서 높은 속도 제어 성능, 친환경성, 에너지 절약, 탁월한 유지 보수성에 있어서 전기 제동시스템이 주목받고 있다. 전기 제동이라 함은 전기 모터의 힘으로써 차량의 속도를 감속하고, 정지하는 것을 말하는데, 감속을 위해 모터에서 역토크를 발생시킴으로써 모터가 발전기로 동작하게 된다. 이때 감소되는 운동 에너지가 전기 에너지로 변환 되는데, 이 에너지를 회생 에너지라 한다. 특히 전동차에서는 추진시스템이 VVVF 인버터로 바뀌어 가면서 회생 제동이 가능해지게 되었지만, 여전히 몇 가지 문제점이 있다. 이러한 문제점을 해결하기 위해서 많은 연구가 진행되고 있다. 본 논문에서는 회생 제동이 기계 제동에 비해서 뛰어난 점을 분석하고 전기 제동법이 안고 있는 문제점을 언급한다. 또한 이를 보완하기 위한 방안으로서 연구되고 있는 방법을 나열하고 각각의 특성에 대해 살펴본다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.157-158
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• 2015

본 논문은 직렬 보상 커패시터 사용으로 인해 발생될 수 있는 SSR(Subsynchronous Resonance) 현상을 해석하기 위한 도구로서 EMTDC의 활용에 관해 다루고 있다. EMTDC를 이용한 순시치 기반의 계통 해석은 주파수 스캔이나 Eigenvalue 계산법의 한계를 보완할 수 있다. EMTDC 기반 해석의 효용성을 검증하기 위해 IEEE 2nd Benchmark 모델을 PSCAD/EMTDC로 구현하였고, 시뮬레이션을 통해 유도 발전기 효과와 비틀림 상호작용 및 축 토크 증폭 현상을 검증했다. 또한, SSR의 억제 수단으로 SVC와 보조제어기를 발전기단에 투입하였고, 그 억제 효과를 시뮬레이션으로 검증하였다.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.33-37
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• 2002

This paper presents a simple torque estimation method and the switching angle control of SRM using Neural Network. SRM has gaining much interest as industrial applications due to the simple structure and high efficiency. Adaptive switching angle control is essential for the optimal driving of a SRM because of the driving characteristic varies with the load and speed. The proper switching angle which can increase the efficiency was investigated in this paper Neural Network was adapted to regulate the switching angle and nonlinear inductance modelling. Experimental result shows the validity of the switching angle controller.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.293-296
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• 2002

This paper presents an implementation of Direct torque control(DTC) of Reluctance Synchronous Motor(RSM) drives for an industrial servo drive system with stator current space vector. The estimation of the stator flux magnitude are obtained by using the neural network from measuring the modulus and angle of the stator current space vector. The develolled digitally high-performance control system are shown a good response characteristic of control results and high performance features using 1.0kW RSM.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.467-470
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• 2002

Internet provides the useful method to monitor the current states of the machine tool no matter where a personnel is monitoring them. In this paper, a monitoring method of the torque of the machine tool's spindle induction motor using internet is suggested. The torque of vector controlled induction motor is estimated without speed measuring sensor. Only stator currents are measured to estimate the magnetizing current which is used to calculate flux linkage, rotor velocity and motor torque. Graphical programming is used to implement the suggested algorithm, to monitor the torque of an induction motor in real time and to make the estimated torque monitored on client computers. To solve the fluctuation problem of estimated torque caused from instantly varying rotating speed of an induction motor, the rotating speed is reconstructed based on the measured current signals. Mechanical part of the machine tool is also reconstructed using the data obtained from preliminary experiments. Torque of the spindle induction motor is well monitored on the client computers with 3% error range under various cutting conditions.