• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.225-229
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• 1998

If there is a mismatch between the controller programmed rotor time constant and the actual time constant of motor, the decoupling between the flux and torque is lost in an indirect rotor field oriented control. This paper presents a new estimation scheme for rotor time constant using artificial neural networks. The parameters of induction motor model organize 2 layer neural to be weight between neuron, which is proposed new in this paper. This method makes networks simple, so its brings not only the improvement in speed but simplification in calculation. Furthermore, it is possible to estimated rotor time constant real time through on-line learning without using off-line learning. The digital simulation and the experimental results to verify the effectiveness of the new method are described in this paper.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.304-309
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• 2003

A new modal analysis method for rotor systems with periodically time-varying parameters is proposed. The essence of method is to introduce modulated coordinates to derive the equivalent time-invariant equation. This paper presents a modal analysis method using modulated coordinates fur general rotors, of which rotating and stationary parts both possess asymmetric properties. The equation of motion with time-varying parameters is transformed to an infinite order matrix equation with the time-invariant parameters. A theory of modal analysis for the system is presented with the infinite order equation and a couple of reduced order equations. A numerical example with simple asymmetric rotor is provided to demonstrate the effectiveness of the proposed method

• International Journal of Aeronautical and Space Sciences
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• 제5권2호
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• pp.35-42
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• 2004

Among other critical conditions in rotor svstems the large non-linearvibration excited by bearing non-linearity causes the rotor failure. For reducing thiscatastrophic failure and predictive analysis of this phenomena the identificationanalysis of bearing non-linearity in an anisotropic rotor system using the higherorder dFRFs are developed and are shown to be theoretically feasible as innon-rotating structures. For the identification of the anisotropic rotor withanisotropic bearing non-linearity expressed by the displacement in polynomial form,the higher order dFRFs based upon the Volterra series are investigated and depicttheir features by using the simple forms of the normal and reverse dFRFs. Theyproduce additional sub-harmonic resonant peaks, which indicate the existence ofhigher order non-linearties, and show the energy transfer such that the modes fornormal and reuerse dFRFs are exchanged, which are the fundamental differencesfrom what we can expect in linear ones.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 A
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• pp.64-66
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• 1999

Switched reluctance motor(SRM) has the advantages of simple structure, low rotor inertia and high efficiency. However, position sensor is essential in SRM in order to synchronize the phase excitation to the rotor position. The position sensors increase the cost of drive system and tend to reduce system reliability. This paper investigates the speed control of sensorless SRM in which the phase current and change rate are utilized in position decision, and the period of dwell angle is variable by compensating the rotor angle. The proposed system consists of position decision, phase locked loop controller, switching angle controller and inverter. The performances in the proposed system are verified through experiments.

• 대한기계학회논문집A
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• 제21권6호
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• pp.896-906
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• 1997

The effect of duplicate flexible disks on the vibrational modes of a flexible rotor system is investigated by using an anlytical method based on the assumed modes method. The rotor model to be analyzed consists of duplicate disks on a flexible shaft. In modeling the system, centrifugal stiffening and disk flexibility effects are taken into account. To demonstrate the effectiveness of the method, a hard disk drive spindle system commonly used in personal computers and a simple flexible rotor system with two disks are selected as examples. In particular, the dynamic coupling between the vibrational modes of the shaft and the duplicate disks is investigated with the shaft rotational speed varied.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1441-1443
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• 2005

In this paper proposes a very simple method to estimate the rotor position of a switched reluctance motor. By on-line estimating the self-inductance of the motor, the rotor position of the SR motor is obtained, and a closed-loop drive system can be achieved. Proposed methods can easy implement to application with sensorless SR motor drive system. SR motor simulation executed with self inductance estimation and result represented. Simulation result verified the rotor position using the proposed self-inductance estimation method.

• Journal of Magnetics
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• 제18권3호
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• pp.255-259
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• 2013

In this paper a new coupling method for efficient and simple analysis of single phase induction motor is presented. The circuit representation of both the stator winding and each conducting rotor loop (composed of rotor bar and end ring segment) is used in conjunction with the distribution of magnetic flux linkage instead of inductance matrix. The flux linkage is calculated using air-gap flux density distributions driven by unit currents in the stator windings and rotor bars. The field distribution of one turn of a coil is calculated by FEM and the result is used to calculate total flux linkage by employing a coordinate transformation. The numerical results give good agreement with prior literature. The method is particularly effective in analyzing the effect of the number of rotor bars.

• Smart Structures and Systems
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• 제22권2호
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• pp.139-150
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• 2018

A variable electromotive-force generator (VEG), which is a modified generator with an adjustable overlap between the rotor and the stator, is proposed to expand the operational range of a regular generator through a simple and robust active control strategy. It has a broad range of applications in hybrid vehicles, wind turbines, water turbines, and similar technologies. A mathematical model of the VEG is developed, and a novel prototype is designed and fabricated. The performance of the VEG with an active control system, which adjusts the overlap ratio based on the desired output power at different rotor speeds for a specific application, is theoretically and experimentally studied. The results show that reducing the overlap between the rotor and the stator of the generator results in reduced torque loss of the generator and an increased rotational speed of the generator rotor. A VEG can improve the fuel efficiency of hybrid vehicles; it can also expand operational ranges of wind turbines and water turbines and harness more power.

• 한국정보통신학회논문지
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• 제6권6호
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• pp.873-878
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• 2002

고정자 전류 스펙트럼(stator current spectrum)은 유도전동기의 고장 검출에 널리 사용되어왔다. 본 논문에서는 고정자 전류 스펙트럼 중에서 회전자 고장에 의해서 큰 영향을 받는 주파수 성분들로 특징벡터(feature vector)를 구성하고, 특징벡터와 기준벡터(reference vector)와의 평균 절대치 차이(mean absolute difference)를 구함으로써, 회전자 고장을 검출하는 방법을 제안한다. 제안한 방법에서는 전류 스펙트럼 중에서 추출된 매우 작은 크기(dimension)의 특징 벡터에 대한 평균 절대치 차이를 이용하기 때문에 신경회로망에 의한 고장 검출 알고리즘 둥에 비해서 훨씬 적은 계산량만으로 모터의 고장을 효율적으로 검출할 수 있다

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.739-740
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• 2006

According to the rapid growth of high speed and precise industry, the application of synchronous motor has been increased. In the application fields, the large synchronous motor is not a self-starting motor. The rotor is heavy and, from a dead stop, it is impossible to bring the rotor into magnetic lock with the rotating magnetic field for this reason, all synchronous motor have some kinds of starting device. A simple starter is another motor which brings the rotor up to approximately 96 percent of it synchronous speed. The starting motor is disconnected and the rotor locks in step with the rotating field. The more commony used starting method is to have the rotor to include a squirrel cage indution winding. This indution winding brings the rotor almost to synchronous speed as an induction motor. So, this paper describes excessive condition interpretation of a exciter circuit to prevent starting failure of large synchronous motor. the large synchronous motor needs safety of it in accordance with operating frequent start and stop. the operating Problem point of synchronous motor appears potential element damage of Exciter circuit because synchronous motor is caused synchronous separation. hence we eliminate it and improve starting toque.