• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.9 no.3
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• pp.88-96
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• 1995

High speed elevator requires precise drive included in zero speed at start/stop drive for the high stability and controllability. The vector control techniques, which have been used for the precise operation of induction motor, can be divided into two classes; The indirect vector control by slip frequency and the direct vector control by field orientation. The existing direct vector control technique has a robustness against the change of motor parameter and the existing indirect vector control technique has a strength of control ability in the wide speed range comparatively. This study presents the DTIF (Direct Torque Indirect Flux) controller which has robust movement in the transition state and in about zero and low speed using the control technique in which torque is controlled by the direct vector technique and flux is controled by indirect vector technique. The proposed system is verified by simulation and experiment for driving 3 phase induction motor. The process of transition which is from about zero speed and low speed to high speed is compared and measured to specification of phase voltage, phase current and DC link current. It is verified that DTIF controller show robust and stable speed variation.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.8
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• pp.1105-1110
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• 2011

This paper presents an improved direct torque control based on artificial neural networks technique. The major problem that is usually associated with DTC drive is the high torque(speed) ripple. To overcome this problem a torque hysteresis band with variable amplitude is proposed based on artificial neural networks. The artificial neural networks proposed controller is shown to be able to reducing the torque(speed) ripple and dependency on motor parameter and to improve performance DTC especially at high speed and reversal running.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.12
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• pp.2618-2624
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• 2009

Harmonics (or distortion in wave form) has always existed in electrical power systems. It is harmless as long as its level is not substantial. However, with the recent rapid advancement of power electronics technology, so-called nonlinear loads, such as variable frequency drives for motor power/speed control, are increasingly finding their way to shipboard or offshore applications. In this paper a new approach to direct torque control (DTC) of induction motor drive is presented. In comparison with the conventional DTC methods the inverter switching frequency is constant and is dramatically increased, requiring neither any increase of the sampling frequency, nor any high frequency dither signal. The well-developed space vector modulation technique is applied to inverter control in the proposed DTC-based induction motor drive system, thereby dramatically reducing the current harmonics. As compared to the existing DTC approach with constant inverter switching frequency, the presented new approach does not invoke any concept of deadbeat control, thereby dramatically reducing the computations.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.596-599
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• 2000

벡터 제어이론은 교류전동기의 토오크와 자속을 독립적으로 제어할 수 있는 특징이 있으므로 토오크 제어를 주로 하는 견인용 전동기의 제어에 적용하기 위한 연구가 활발히 수행되어 왔다 그러나 선형 유도전동기 구동에는 아직 널리 사용되지 않은 실정이다 벡터 제어이론은 일반적으로 회전자자속 기준제어(Rotor flux oriented control)을 의미하며 이를 구현하기 위한 방법은 자속을 직접 측정 혹은 연산하는 직접제어 방식과 속도를 측정하여 슬립주파수 명령을 제어하는 간접방식으로 분류된다. 최근에는 기존의 회전자자속 기준방식뿐만 아니라 고정자자속(Stator flux oriented) 공극자속(Air gap flux oriented) 기준 방식등이 제안되고 있다. 본연구에서는 자기부상열차의 추진용 선형 유도 전동기의 추진에 가장 적합하다고 생각되는 고정자자속 기준벡터제어 방식과 이를 구현하기 위한 고정자 자속을 추정하는 방법에 대하여 설명한다. 또한 속도제어를 위한 속도 추정방식도 안내코일 등 부장치 없이 전동기 파라미터로 추정할 수 있는 기법에 대하여 논한다.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.5
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• pp.427-434
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• 2000

The paper proposes a zero speed start-up scheme of direct rector controlled induction motor drive without any torque jerk. At standstill condition, a method is derived to calculate a stator flux with only stator current. The programmable 3-stage low pass filters with programmable time constants is used in order to solute the problem of integration for stator flux estimation in the direct vector control mode. Due to the time delay of 3-stage low pass filter, the status flux decreases rapidly and also the torque jerk occurs during the transition from standstill mode to the direct rector control mode. A feedforward control strategy of the stator flux is suggested to prevent the torque jerk at start-up. Through results of simulation and experiment with 32 bit DSP, the performance of the start-up scheme is verified.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.3
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• pp.66-74
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• 2005

This paper presents an implementation of digital servo speed control system of SPMSM(Surface-mounted Permanent Magnet Synchronous Motor) for industrial application with Direct Torque Control(DTC) using TMS320F2812 DSP. Although, the vector control scheme is adapted in many industrial servo system, but the DSP calculation ratio is increased by reference frame transformation and SVPWM of vector control. Therefore, this paper investigate the possibility of DTC scheme for industrial servo drive system instead of vector control scheme. DSP calculation ratio is compared between vector control and DTC algorithm in addition to the characteristic of speed control response. The suggested SPMSM control system shows the possibility of DTC scheme for industrial servo motor drive system instead of a vector control algorithm.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.509-513
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• 1999

본 논문은 유도전동기의 직접벡터제어 시스템에서 전동기가 기동 시 토크 충격없이 부드럽게 기동할 수 있는 기동기법을 제시한다. 직접 벡터제어에서 고정자 자속을 계산 시 사용되는 적분기 문제를 해결하기 위하여, 인버터주파수에 따라 시정수를 제어하는 프로그램어블 3-단계 저역필터를 적용한다. 이 3-단계 저역필터는 거의 완벽한 적분기능을 수행 할 수 있으나, 이 저역필터는 고정자 자속의 시간지연을 유발하므로 기동 시 전동기 토크의 충격을 발생된다는 문제점이 있다. 따라서, 기동시 고동자 자속의 시간지연을 보상하는 고장자 자속의 피이드포워드 기법을 제시하여, 전동기 기동 시 토크 충격을 방지한다. 시뮬레이션을 통하여, 이 기동기법의 타당성을 확인한다.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1257-1259
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• 2000

직접토크제어(DTC)가 빠른 포크 응답을 가지고있다는 것은 널리 알려진 사실이다. 이것은 기존의 벡터 제어와는 달리 공간 전압벡터에 의해 직접적으로 토크와 자속이 제어되기 때문이다. 이로 인해 직접토크제어 기법은 그것이 도입되어진 1980년대 중반 이래로 노크의 빠른 응답을 필요로 하는 분야에 점차적으로 적용되어져 왔다. 하지만 이런 장점에도 불구하고 직접토크제어는 히스테리시스 밴드, 속도 그리고 전동기 파라메타의 변화에 따른 스위칭 주파수의 변화와 토크 리플의 증가, 좋은 성능을 위한 높은 제어 주기 등의 몇 가지 단점을 가지고 있었다. 그래서 DTC의 단점들을 해결하기 위해 여러 연구들이 이루어져 왔다. 본 논문에서는 이들 단점들 중 하나인 토크리플을 개선하려한다. 다른 논문들에서도 일정 주파수를 가지는 여러 제어 기법을 사용하여 직접토크제어의 단점을 해결하려 했지만 너무 복잡하고 큰 성능을 나타내지 못했으며 몇몇 논문들은 오히려 직접토크제어의 장점인 빠른 응답성을 잃는 결과도 가져왔다. 그래서 본 논문은 간단한 개념을 가지고 토크리플을 줄이며 일정 스위칭 주파수를 가지므로 DSP를 사용하여 제어하기 용이한 직접토크제어기법을 제안하려 한다.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.387-388
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• 2014

3상 AC/AC 2단계 직접형 전력변환시스템(TSDPC)의 제어는 입력전류공간벡터와 출력전압공간벡터를 합성한 공간벡터 PWM 스위칭패턴을 통해 제어를 하며, 이를 기반으로 계산된 유효벡터인가시간에 따라 TSDPC를 구성하는 다수 스위칭소자가 절환 됨을 통해 많은 스위칭손실이 발생하는 문제점이 있다. 본 논문에서는 스위칭 시퀀스를 간략화하여 스위칭 절환횟수를 줄임과 동시에 부분 영전류 스위칭 제어기법을 도입하여, 스위칭손실 저감 제어기법을 제안한다.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.1
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• pp.90-98
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• 1998

This paper is to describe the improved vector control which can control the induction motor robustly in low speed. When the induction motor is drived with low speed, below 10 percent of the rated speed, an algorithm which can compensate the error of unit vector angle generated by the harmonics is proposed. Another algorithm which can be tuned to the rotor time constant so that nay be robust to the rotor parameter change in low speed and transient state was proposed. The ripple of flux and torque was reduced by the proposed vector control and then the stable output characteristics was obtained in low speed. When the input and output is sinusoidal, the proposed vector control, the direct vector control and the indirect vector control were analyzed and compared in the low speed characteristics. And each control characteristics is compared and analyzed in state of containing harmonics. The estimation and tunning performance of rotor time constant is confirmed with simulation. The whole control system is implemented by real hardware and experimented to compare the proposed vector control with the direct vector control. As a result of the experiment with two control methods in low speed, the torque ripple of the proposed vector control is improved by 45 percent than the direct vector control. And it is confirmed that the flux current ripple is reduced in 0.2 p.u. and torque current ripple is reduced in 0.6 p.u. It is confirmed that the rotor time constant by the estimation and the tunning algorithm is tunned by the real rotor time constant. Finally, it was confirmed that the validity and robustness for the proposed vector control in low speed existed.