• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.65-68
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• 2001

In the vector control methods of induction motor, the stator current is divided into the flux and torque component current. By controlling these components respectively, the methods control independently flux and torque as in the DC motor and improve the control effects. To apply the vector control methods, the position of the rotor current is identified. The indirect vector control use the parameters of the machine to identify the position of rotor flux. But due to the temperature rise during machine operation, the variation of rotor resistance degrades the vector control. To solve the problem, the q-axis is aligned to reference frame without phase difference by comparing the real flux component with the reference flux component. Then to compensate the slip, PI controller is used. The proposed method keeps a constant slip by compensating the gain of direct slip frequency when the rotor resistance of induction motor varies. To prove the validations of the proposed algorithm in the paper, computer simulations is executed.

• 대한전기학회논문지
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• 제35권9호
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• pp.403-408
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• 1986

In this paper, the method to improve the efficiency of an induction motor at light load is discussed. Efficiency of induction motor can be very substantially improved by keeping the slip frequency as constant. Therefore, to simplify the control loop, algorithm which maintain constant slip frequency and control the input voltage is adopted. Simplified high efficiency drive of induction motor using PLL technique is suggested. In order to verify the validity of this system, the test results are compared with those obtained by optimal slip drive system and then we found closer to the optimal efficiency. For example its efficiency is improved from 18[%] to 42[%] at a few fraction of the full load (20[%]).

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.289-291
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• 1996

Linear induction motor(LIM) is widely used to drive magnetic levitation train. To drive LIM, different control method compared with conventional rotary type machine is needed. Since vertical force is generated inherently and it effects on the levitation system, vertical force should be kept constant for stable levitation. To keep vertical force constant, slip frequency should be kept constant. Once slip frequency is kept constant, tractive force can be controlled by adjusting motor currents. In this paper, control methods used so far arc analyzed with some experimental results and decoupling control algorithm is proposed to control tractive and vertical force separately. Control algorithm is verified through simulation.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.403-405
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• 2007

This paper presents the over-modulation strategy and indirect vector control drive of NPC type PWM inverter. NPC inverter has three level phase voltage output.It can perform in high voltage through assembling switching components. It has less harmonics and surge voltage stress at motor terminals than the 2 level inverter in same switching frequency through 3 level voltage. The conventional railway vehicle has used the vector control to MI=0.907 and the slip-frequency control from MI=0.907 to six-step mode. The slip-frequency control has bad motive power and slow torque control response. But vector control has good motive power and can instant torque control. In this paper, output voltage is controlled linearly from linear region to six-step mode by using over-modulation strategy. And NPC inverter is used.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(I)
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• pp.440-445
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• 2002

In this paper, traction system for urban transit maglev system is proposed. Using vector control strategy to control magnitude and frequency of output voltage transiently is general. But in case of traction system for railway vehicle, it is impossible that adapt vector control because there is one-pulse mode in a high speed region. So this paper proposes the control strategy using vector control in a low speed region and slip frequency control in a high speed region. And also proposes overmodulation method that makes to change in one-pulse mode softly. The performance of traction system will be verified by simulation results using ACSL.

• 융합신호처리학회논문지
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• 제5권3호
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• pp.210-215
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• 2004

교류 서보전동기 동적 모델은 비선형이고 2차 저항이 변동영향이 많다. 이러한 복잡한 제어는 견실제어가 요구된다. 이러한 시스템의 동특성은 슬라이딩 모드제어를 사용함으로 파라미터나 외란 변동에 대하여 견실성을 달성할 수 있다. 본 논문은 교류 서보전동기에 의한 위치제어에 슬라이딩 모드 제어의 적용을 나타내었다. 제어방법이 유도되고 제어시스템이 설계되었다. 교류 서보전동기의 견실제어를 위해 외부 부하 파라미터에 기초한 설계방법이 제안되었다. 제안된 제어방법은 가변구조 제어기와 슬립주파수형 벡터제어에 기초하여 주어졌다. 시뮬레이션 결과는 관성모우먼트, 점성마찰 및 부하외란 변동에 결실함을 나타내었고 슬라이딩 모드를 적용한 제안된 설계방법이 유용한 것을 구명한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.361-363
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• 2007

In this paper, an auto-diagnosis method of rotor bar fault for small induction motor is suggested. Usually FFT of stator currents are given the good results, but to detect the fault, slip is needed for calculating the feature frequency. The slip is varied as the load is changed. So in this paper, some alternative method for estimating the load is suggested. This method is based on the Park's vector pattern. The magnitudes of the feature frequency are compared with the threshhold that is predefined in the bounded range of load. The healthy rotor, single rotor bar fault and double rotor bar fault are tested with no load, 25%, 50%, 75%, and 100% rated load. From 50% to 100% rated load case, the rotor bar faults are detectable using indirect estimation of the load and the comparing the magnitudes of feature frequency. The no load case and under 40% rated load case, rotor fault are un detectable.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.65-68
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• 2001

In the vector control methods of induction motor, the stator current is divided into the flux and torque component current. By controlling these components respectively, the methods control independently flux and torque as in the DC motor and improve the control effects. To apply the vector control methods, the position of the rotor current is identified. The indirect vector control use the parameters of the machine to identify the position of rotor flux. But due to the temperature rise during machine operation, the variation of rotor resistance degrades the vector control. To solve the problem, the q-axis is aligned to reference frame without phase difference by comparing the real flux component with the reference flux component. Then to compensate the slip, PI controller is used. The proposed method keeps a constant slip by compensating the gain of direct slip frequency when the rotor resistance of induction motor varies. To prove the validations of the proposed algorithm in the paper, computer simulations is executed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.400-402
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• 1996

The paper describes the control strategy and hardware design for forced commutation cycloconverter which was developed for ac servo motor drive application of vector control. 12-pulse cycloconverter is used to investigate experimentally the performance of an induction motor drive system. The cycloconverter has the facility for continuous control of both the frequency and magnitude of the output voltage to keep a constant flux in the induction motors.

• 한국정보통신학회논문지
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• 제4권2호
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• pp.487-492
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• 2000

본 논문은 유도전동기 간접 벡터 제어시 회전자 시정수 변동에 대한 슬립보상 방법을 제안하였다. 회전자 시정수가 변동하면 고정자 전류의 자속 및 토크 성분의 상호 간섭이 발생하여 벡터제어가 불가능하고 성능이 저하하게 된다. 이를 해결하기 위하여 본 논문에서는 실제 자속 성분과 기준 자속 성분을 비교하여 위상차 없이 자속 성분을 기준 좌표의 q축에 일치시키고 PI 제어기를 이용하여 슬립을 보상하는 방법을 제시하였다. 제안된 방법을 이용하면 유도전동기의 회전자 저항 변동시 q축 자속 성분이 0이 되어 적정 슬립이 유지되고 정확한 벡터제어가 실현된다. 제안된 알고리즘의 타당성을 컴퓨터 시뮬레이션과 실험을 통하여 검증하였다.