• 조명전기설비학회논문지
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• 제20권4호
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• pp.117-122
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• 2006

입력이 최소가 되는 자속의 값을 찾는 유도전동기 고정자자속기준제어의 최대효율제어방법을 제안한다. 제안한 방법에서, 정해진 자속의 값만큼씩 기준자속의 값을 변화시키면서 직류링크에서 측정된 입력의 값이 최소가 되는 기준자속의 값을 찾는다. 또한 철손저항을 고려한 유도전동기의 모델을 이용하여 철손저항을 고려한 토크, 슬립각 속도, 비간섭 보상전류식을 사용한다. 시뮬레이션 및 실험결과를 통해서 제안한 방법의 효과를 입증한다.

• 전력전자학회논문지
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• 제3권2호
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• pp.125-130
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• 1998

본 논문에서는 유도전동기 자속기준제어에 필요한 회전자 자속각 연산을 위한 새로운 자속 연산기를 제시한다. 순수 적분기로 구성된 자속연산기를 사용하여 전압, 전류 정보로부터 실제 회전자 자속을 추정하였다. 제안된 자속 연산기에서는 순수 적분기의 드리프트(drift) 문제를 해결하기 위한 새로운 보상 방법을 도입하였으며, 전동기 속도는 추정된 자속각과 추정된 슬립 주파수로부터 연산하였다. 제안된 방법의 성능을 실험을 통하여 입증하였다. 제안된 시스템의 정경속도의 1/100 이하에서도 안정되게 운전되는 것을 실험결과로부터 확인하였다.

• 대한전기학회논문지
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• 제34권8호
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• pp.331-337
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• 1985

An inverter-excited induction generator is discussed in this paper. A brief review of the capacitor-excited induction generator is given and the steady state characteristics of the induction generator excited by an inverter are evaluated. It is shown that the output voltage of the system can be controlled by adjusting the slip, for given operating conditions. The introduction of feedback control makes it possible to control the output voltage stably over the wide range of speed and load. Experimental results are given. The output of the induction generator is then converted into a CVCF(Constant Voltage-Constant Frequency) power source using a PWM inverter with simple control circuit.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.303-306
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• 1994

This paper presents a new rotor resistance identification algorithm for induction motors. The algorithm is derived form the fact that the slip frequency given in the d-q rotating frame is equal to that measured in the x-y fixed frame. Rotor resistance varies greatly with the machine temperature. In certain cases, the rotor resistance can increase 100 % over its ambient or nominal value. This deteriorates the dynamic performance of vector control systems for induction motors. However, the control scheme proposed in this paper is robust with respect to variations in rotor resistance because an efficient identification algorithm for rotor resistance is employed. To illuminate the performance of the proposed controller further, the simulation results are presented.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.591-593
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• 1996

In order to implement the direct vector control type sensorless vector control, the rotor flux and the angular speed of the rotor can only be estimated through the measurement of the stationary voltage and current states. To estimate the rotor flux, the use of the rotor flux observer(RFO) has been proposed. It is known that the RFO is relatively insensitive to parameter variations. Using the rotor flux value obtained from the RFO, the rotor flux vector can be estimated. The angular speed of the rotor is estimated by the difference between the synchronous angular speed and the slip angular speed, both of which are derived from the rotor flux vector. However unwanted high order frequency waves become incorporated into the synchronous angular speed during calculations. Thus we propose the use of digital filters that will eliminate these high frequency waves. We have demonstrated through computer simulations that the use of filters results in stable system activity over a wide speed range and good response to load variations.

• 한국정보통신학회논문지
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• 제7권5호
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• pp.1013-1018
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• 2003

본 논문은 이차여자 유도발전기시스템의 파력발전시스템에의 적용에 관한 연구내용을 요약한다. 불규칙적인 파력 입력에 따라 변화하는 발전기의 출력을 슬립주파수에 맞추어 컴퓨터로 이차전류를 제어하여 출력전압과 출력전류를 안정화시키고자 하였다. 본 논문에서 제안한 방법을 확인하기 위하여 실험실 레벨의 파력 시뮬레이터를 제작한 후 이차여자 유도발전기를 구동하였다. 파력과 같은 불규칙입력 발전시스템에 대한 이차여자 유도발전 시스템의 유효성을 실험적으로 확인하였다.

• 한국정밀공학회지
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• 제26권6호
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• pp.106-113
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• 2009

A 6-DOF precision stage was developed based on parallel kinematics structure with flexure hinges to eliminate backlash, stick-slip and friction and to minimize parasitic motion coupled with motions in the other-axis directions. For the stage, lever linkage mechanism was devised to reduce the height of system for the enhancement of horizontal stiffness. Frequency response comparison between experimental results and mathematical model extracted from dynamics of the stage was performed to identify the system parameters such as spring constants and damping coefficients of actuation modules, which cannot be calculated accurately by analytic methods owing to their complicated structures. This newly developed precision stage and its identified model will be very useful for precision positioning and control because of its high accuracy and non-coupled movement.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 추계학술대회 논문집 학회본부
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• pp.264-267
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• 1989

In the vector controlled induction machine drives, mechanical speed sensors such as shaft encoder and resolver have been used. However, the mechanical speed sensors present some problems and restrict the wide applications of high performance AC drives. This paper describes the vector control strategy with the speed estimation algorithm in which motor slip frequency is calculated. Also, the angle deviation of the rotor flux vector is calculated and instaneously compensated to keep the q axis flux zero in the rotationary reference frame.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.298-303
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• 1998

In the speed sensorless control of the induction motor, the machine parameters (especially the secondary resistance R2) have a strong influence to the speed estimation. It is known that the simultaneous estimation of the speed and R2 is impossible in the slip frequency type vector control, because the secondary flux is constant. But the secondary flux is not always constant in the speed transient state. In this paper the R2 estimation in the transient state without adding any additional signal to the stator current is proposed. This algorithm uses the least mean square algorithm and the adaptive algorithm, and it is possible to estimate the R2 exactly. This algorithm is verified by the digital simulations and the experiments.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 A
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• pp.353-356
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• 1995

This paper proposes a simple identification method of the rotor time constant to solve the degradation of motor performance due to the difference between the rotor time constant of a controller and actual one in slip frequency type vector control scheme. The proposed method is based on rotor induced voltage equations and it is confirmed that immunity of the stator resistance thermal variation. The simulation results show that the proposed method suitably identifies the rotor time constant in steady state as well as in transient state.