• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1125-1126
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• 2011

고온 초전도 전력기기는 상전도 전력기기에 비해, 중량과 부피가 작고 전력손실이 거의 없어 효율이 높고 대용량기기에 많은 장점을 지니고 있으며 또한 환경 친화적이다. 대형화가 요구되는 선박추진용 모터를 초전도 모터로 사용할 경우 저속 및 고 토크의 모터를 제작할 수 있고, 계자 권선과 전기자 권선을 초전도 선재로 사용함으로써 높은 전류밀도와 고 자장이 가능하여 고효율 및 소형 경량화 등의 장점이 있다. 그러나 전초전도 모터의 경우 얇은 테이프 형태의 초전도 선재의 특성으로 인해 구리선처럼 가공이 힘들고, 선재를 초전도 상태로 만들기 위한 냉각이 필요하다. 이러한 문제점을 해결하기 위하여 본 연구에서는 동기모터와 선형모터를 혼합하여 고정자에 위치한 racetrack type의 전기자 권선뿐만아니라 회전자에 자기장을 발생시키는 계자 권선도 회전자가 아니라 고정자부분에 위치하므로 구조상 견고하고 냉각등에 장점이 있는 호모폴라 모터를 제안하였으며 자기저항의 변화가 작은 구조로 토크 리플이 작으므로 소음과 진동이 적은 모터를 설계하였다. 설계 결과로부터 호모폴라 모터를 제작하였으며 레이스트렉형과 팬케이크 권선의 임계전류등을 측정하였다. 추후 호모폴라 모터의 성능시험을 진행할 예정이다.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.8
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• pp.126-131
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• 2015

The accuracy of motor parameter measurement is necessary to improve the performance of vector control of an induction motor. The rotor time constant affects the performance of controller and also the resistance and leakage inductance of stator are very important design parameters of current and speed controller. In this paper a new modified motor parameter measurement methods for high performance speed control of vector control of an induction motor are proposed.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.2
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• pp.70-78
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• 2005

In this paper, a novel rotor flux estimation method of an induction motor using support vector regression(SVR) is presented. Two well-known different flux models with respect to voltage and current are necessary to estimate the rotor flux of an induction motor. Training of SVR which the theory of the SVR algorithm leads to a quadratic programming(QP) problem. The proposed SVR rotor flux estimator guarantees the improvement of performance in the transient and steady state in spite of parameter variation circumstance. The validity and the usefulness of proposed algorithm are throughly verified through numerical simulation.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.1
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• pp.43-49
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• 1999

We propose a nonlinear feedback controller that can control the induction motors with high dynamic performance and high power efficiency by means of decoupling of motor speed and rotor flux. The nonlinear feedback controller needs the information on some motor parameters. New recursive adaptation algorithms for rotor resistance and mutual inductance which can be applied to our nonlinear feedback controller are also presented in this paper. The recursive adaptation algorithms make the estimated values of rotor resistance and mutual inductance track their real values. Some simulation and experimental results show that the adaptation algorithms are robust against the variation of stator resistance and stator inductance.

• Korean Journal of Materials Research
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• v.8 no.2
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• pp.135-140
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• 1998

Drag reduction produced by dilute solution of water soluble ionic polymer-surfactant complex under turbulent flow in a rotating disk apparatus(RDA) was investigated in this study. Three different molecular weights of polyacrylic acid(PAA) were adopted as drag reducing additives, and distilled water was used as a solvent. Experiments were undertaken to observe the dependence of drag reduction on various factors such as polymer molecular weight, molecular expansions and flexibility, rotating speed of the disk and polymer concentration. Specific considerations were put on conformational difference between surfactant and polymer, and effect of pH on ionic polymer possessing various molecular conformation through pH. The complex of ionic polymer and surfactant(Sodium Dodecyl Sulfate) behaves like a large polyelectrolyte. Surfactant changes the polymer conformation and then increases the dimension of the polymer. The radius of gyration, hydrodynamic volume and relative viscosity of the polymer-surfactant system are observed to be greater than those of polymer itself. Such surfactant-polymer complex has enhanced drag reduction properties.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.12-14
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• 1996

In this paper, the simulation of the effects of variation of rotor resistance of induction motor for the performance of vector control is presented. Especially, this paper considered the effects as a difference variation of the rotor resistance between slip calculator and induction motor.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.239-244
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• 1998

We propose a nonlinear feedback controller that can control the induction motors with high dynamic performance by means of decoupling of motor speed and rotor flux. A new recursive adaptation algorithm for rotor resistance which can be applied to our nonlinear feedback controller is also presented in this paper. Some simulation results show that the adaptation algorithm for rotor resistance is robust against the variation of stator resistance and mutual inductance. In addition, it is computationally simple and has small estimation errors.

• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.326-331
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• 1990

In the vector-controlled induction machine drive, mechanical sensors restrict the wide applications of high performance AC drives. So in resent years, many papers have been presented which doesn't need mechanical sensors, named by sensorless vector control. But sensorless control has a few serious problem, one of which Is poor speed estimation in case of incorrect rotor resistance (Rr) information. This paper describes the stator flux orientation speed control strategy with the speed estimation algorithm. and the method of adapting Rr change due to thermal heating. By proposed method. We can acquire precise speed estimation and higher performance.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.412-414
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• 1996

The rotor resistance variation has a large effect on the field oriented control system of induction machine. In this paper, the adaptation technique based on MRAC is used to identify the rotor resistance variation. The criterion function used in the adaptation algorithm is the error function of the two reactive powers of the induction motor. The one is obtained from the voltages and the currents of the stator of the induction motor. And the other is estimated from the rotor flux and stator current. We simulated this control system operated by field oriented control and assured the robustness of the induction motor control system against the rotor resistence variation.

• Proceedings of the KIEE Conference
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• 1994.07a
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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.