• 대한전기학회논문지
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• 제45권3호
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• pp.365-373
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• 1996

This paper presents the effects of rotor time constant variation and the on-line tuning algorithm of the rotor time constant. If the value of the rotor time constant is set incorrectly, the IFOC (Indirect Field Oriented Control)scheme exhibits deteriorated performance according to the wrong slip command. These variation effects of the rotor time constant are caused by the slip calculator where it is known that the rotor time constant play an important role in the aligned rotor flux. Using the two torque angles (stationary torque angle, rotating torque angle), the variation of the rotor time constant is identified, and the rotor time constant of the controller is tuned to the proper value of the machine. As the result, with the proposed algorithm, the dynamics of the deteriorated IFOC system, where the rotor time constant is varied, is improved. For the purpose of the validity of this proposed algorithm, the computer simulations and the experiments have been performed and the explanation of the results is presented. (author). refs., figs., tab.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.195-198
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• 1997

This paper proposes the effective compensation method of the rotor time constant of induction motor. An indirect vector control method is highly dependent on the motor parameters. To solve the problem of performance degradation due to parameter variation in an indirect vector control of induction motor, we compensate the rotor time constant by current error feedback. The proposed method is a simple on-line rotor time constant compensation method using the information from terminal voltages and currents. As the current error, difference between current command and estimated current, approaches to zero, the value of rotor time constant in an indirect vector controller follows the real value of induction motor. This scheme is valid transient region as well as steady state region regardless of low or high speed. This method is verified by computer simulation. For this, we constructed the simulation model of induction motor, indirect vector controller and current regulated PWM (CRPWM) voltage source inverter (VSI) using SIMULINK in MATLAB.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 추계학술대회 논문집
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• pp.21-24
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• 2002

The vector control system of an induction motor is the high performance drive system to achieve the instantaneous torque control. The vector control system is greatly divided into the direct control, and the indirect control that the most widely is used, The indirect vector control needs the rotor time constant, which changes widely according to the temperature, frequency, and current amplitude. The incorrect time constant leads to the saturation of magnetic flux or under-excitation phenomena. As a result, that deteriorate the control performance. Therefore, in this paper, the effect of time constant variation is investigated and its on-line tuning algorithm is proposed. The time constant using the torque angles was calculated and that of the validity of algorithm proposed was proved through the computer simulation and the experiment.

• 전력전자학회논문지
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• 제10권2호
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• pp.155-161
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• 2005

본 논문에서는 MRAS 퍼지제어를 이용한 회전자 시정수 추정 기법을 제안한다. 회전자 자속을 추정하는 방법은 기준모델과 적응 회전자 모델을 이용한다 이 두 모델은 MRAS의 형태로 구성되며 두 모델의 오차를 영으로 근접하게 제어한다. 두 모델의 파라미터가 정확하면 동일한 결과를 얻는다. 그러나 회전자 시정수의 추정이 정확하게 이루어지지 않으면 두 회전자 자속의 추정은 서로 다른 각도를 가지게 된다. 두 모델의 오차와 오차 변화분을 입력으로 퍼지 제어기를 이용하여 회전자 시정수를 추정한다.

• 전력전자학회논문지
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• 제9권5호
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• pp.413-419
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• 2004

고피나스 모델 자속관측기를 사용한 유도전동기 직접벡터제어 시스템에서 회전자 시정수에 오차가 있을 경우 시스템의 동특성이 저하되는 현상을 살펴보았으며, 이를 해결하기 위한 방안으로 MRAC를 이용한 회전자 시정수 실시간 추정 알고리즘을 제안하였다. 제안한 방식의 타당성을 검증하기 위해서 자속관측기에 사용되는 전동기 상수들의 오차가 회전자 시정수 추정에 미치는 영향을 실험적으로 분석한 결과 전동기 상수에 다소 오차가 있더라도 회전자 시정수의 추정오차는 5% 이내로 수렴됨을 보였다. 따라서 본 연구에서 제안한 회전자 시정수 추정 알고리즘을 고피나스 모델 자속관측기에 적용하게 되면 전동기 상수 변동에 강인한 유도전동기 직접벡터제어 시스템을 구현할 수 있다.

• Journal of Power Electronics
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• 제14권5호
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• pp.1000-1007
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• 2014

This paper proposes an on-line rotor time constant estimation strategy for indirect field oriented induction machines. The performance of the indirect field oriented control is dependent especially on the rotor time constant whose value varies according to the temperature. The proposed method calculates the difference between the nominal rotor time constant and the real value from the d- and q-axis integration terms of a proportional integral (PI) current regulator and the demanded voltages of the induction machine to regulate the current in the steady state. Because the proposed strategy has a simple structure and is available in wide speed and torque ranges, the proposed method can be easily used in the industrial field. The effectiveness of proposed strategy is verified with simulations and a 7.5kW experimental setup.

• Journal of Welding and Joining
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• 제33권2호
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• pp.47-55
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• 2015

With using adaptive control of the resistance spot welding machine, the advantage on electrode life time for galvanized steels has been addressed. This study was aimed to evaluate the electrode life time of galvanized steels with applying the constant current control and the adaptive control resistance spot welding process for a comparison purpose. The growth in diameter of electrode face was similar for both the constant current and the adaptive control up to 2000 welds. The button diameter was decreased with weld numbers, however, sudden increase in button diameter with use of the adaptive control after 1500 welds was observed. The peak load was continuously decreased with increasing number of welds for both the constant current and the adaptive control. The current compensation during a weld was observed with using the adaptive control after 1800 welds since the ${\beta}$-peak on dynamic resistance curve was detected at later weld time. The current compensation with adaptive control during resistance spot welding enhanced the nugget diameter at the faying interface of steel sheets and improved the penetration to thinner steel sheet.

• 대한전자공학회논문지
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• 제11권3호
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• pp.27-31
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• 1974

Pontryagin의 최대원리의 놀라운 방식을 써서 원자로에 있어서 최적제어 switching시간과 최적제초 switching 점을 구하였다. 그리고 원자로의 초기상태에서 그의 목표상태로 출력을 변환시킬 때의 제어궤적을 시간최적제어 방식을 이용하여 주어진 원자로의 parameter 값과 piecewise constant 입력값에 따라 최적화 시켰다.

• 전기학회논문지
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• 제64권11호
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• pp.1571-1577
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• 2015

A new mixed mode control of constant power and constant current for resistance spot welding inverter is proposed to improve the weld quality. The conventional control scheme adopts constant current or constant power control mode, however, it is not easy to guarantee the high weld quality because of the nonlinear resistance characteristics of the welding point. The proposed method utilizes the nonlinear characteristics by measuring the dynamic resistance in real time. Therefore, it is possible for the welder to be controlled adaptively depending on the welding state. Experimental results show that the proposed control scheme improves the weld quality by 6.8 times compared with the conventional constant current mode control.

• 제어로봇시스템학회논문지
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• 제4권5호
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• pp.585-591
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• 1998

It is proposed a new compensation method in the rotor time constant of indirect vector controlled induction motor. The proposed scheme is an on-line method using the stator current error that is the difference between current command and estimated current calculated from terminal voltages and currents. As the current error becomes to zero, the rotor time constant in the vector controller approaches the real value. The proposed method shows good performances in the transient region as well as in the steady state region regardless of load torque variation, and it is verified by the computer simulation using SIMULINK in Matlab.