• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.8
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• pp.413-424
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• 2002

Recently, in the linear motion system, high performances are required In dynamic characteristics. Vector control method is capable of instantaneous thrust control can meet these high performance requirements. Linear induction motor(LIM) have static and dynamic end effects due to its finite core length, so that per-phase impedances are asymmetric and an air gap flux distribution is distorted. These points of the d-q axis equivalent circuit model considering both end effects is more complicated. This paper proposes the d-q axis equivalent circuit and the vector control method considering both static and dynamic end effects of the LIM. As a result, it is shown that the results of the equivalent circuit method(ECM) have a good agreement with those of the finite element method(FEM).

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.8
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• pp.425-433
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• 2002

This research investigates the electromechanical characteristics of a sing1e-phase squirrel cage induction motor due to broken rotor bars and rotor eccentricity. Numerical analysis is performed by solving the nonlinear time-stepping finite element equation coupled with the magnetic field equation, circuit equation and mechanical equation of motion. It shows that the asymmetry of magnetic flux due to the broken rotor bars and rotor eccentricity introduce a change in the stator current, torque, speed, magnetic force and vibration of a rotor at the same time. However, even in the existence of rotor eccentricity, 3 broken rotor bar introduces a dominant change in the magnetic force and rotor displacement, i.e., beating phenomenon in time domain and sideband frequencies in frequency spectra, respectively.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.3
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• pp.229-236
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• 2008

Recently, multilevel H-bridge inverters have become popular in medium to high power ac drive applications. One of significant advantages of them is low harmonic contents in their input line currents thanks to the transformer with multiple phase-shifted secondary windings. This paper attempts to provide basic guidelines for the design of the phase shifting transformer windings and theoretical analysis of input line current harmonics of H-bridge inverters. The part I provides the derivation of basic relationships between input and output current of the transformer and the relationship between the phase shifting characteristics and design aspects of the transformer.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.48-53
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• 1989

We attempt to achieve both high dynamic performance and maximal power efficiency by means of linear decoupling of rotor speed (or motor torque) and rotor flux. The induction motor with our controller possesses the input-output dynamic characteristics of a linear system such that the rotor speed (or motor torque) and the rotor flux are decoupled. The rotor speed (or motor torque) responses are not affected by abrupt changes in the rotor flux and vice versa. The rotor flux need not be measured but is estimated by the well-known flux simulator. The effect of large variation in the rotor resistance on the control performances is minimized by employing a parameter adaptation method. To illuminate the significance of our work. we present simulation and experimental results as well as mathematical performance analyses.

• 전기의세계
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• v.30 no.11
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• pp.734-746
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• 1981

This paper suggests on-load torque measurement for 3 phase induction motors by input -voltage and current utilizing symmetric coordinate analysis technique on the basis of the induction motor equivalent circuit. In this paper, two cases are treated with, i.e, one is the case where the motors' exciting current and primary leakage impedance voltage drop are compensated automatically, adopting the ideal wattmeter whose current coil impedance and voltage coil impedance are 0 and .inf. respectively, and the other is the case where non-ideal wattmeter is adopted and the compensation above is made by computation. As a result of the case study, following conclusions are obtained. 1) By proper combination of the error propagation law and the limit of power consumption, the desirable overall measurement error of the apparatus can be obtained on the basis of the inherent errors of CT and PT. 2) The measurement error is larger in current simulation circuit than in voltage simulation circuit. 3) Between the two cases, the latter is more advantageous than the former from the viewpoint of feasibility and the measurement error. 4) As the attachment of Ammeter in the current simulation circuit influences the measurement error considerably, its internal impedance should be large considerably. 5) The larger the consumption power of the apparatus is, the easier the feasibility is.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.516-518
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• 1999

This paper presents an feed-forward neural network design instead PI controller for the speed control of an Induction Motor. The design employs the training strategy with Neural Network Controller(NNC) and Neural Network Emulator(NNE). Emulator identifies the motor by simulating the input and output map. In order to update the weights of the Controller. Emulator supplies the error path to the output stage of the controller using backpropagation algorithm. and then Controller produces an adequate output to the system due to neural networks learning capability. Therefore it becomes adjustable to the system with changing characteristics caused by a load. The speed control based on neural networks for induction motor is implemented by a vector controlled induction motor. The simulation results demonstrate that actual motor speed with neural network system well follows the reference speed minimizing the error and is available to implement on the vector control theory.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.1
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• pp.72-77
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• 2015

When connecting 6 lead wires from stator windings to the terminals of 3 phase induction motors for Y or ${\triangle}$ connection, it is feared that the polarities of windings could be reversed each other if the wire tags are lost or erased, resulting in inadmissibly high current to motors in case of starting. To protect motors against such situations, some test procedures are necessary during wire connection which need to be easy ways to electricians without particular tools except a general multi-tester and with less time-consuming in the field. This study focuses on a test measure to satisfy these requirements which is able to provide them a convenient procedure for winding polarity discrimination considering the field condition. Here, the proposed measure utilizes the residual magnetism of the rotor and checks the indication of voltage or current at windings which are induced by the residual flux of rotor when rotating it by hands with 3 stator windings connected in the form of I connection. Principle characteristics and experiment results for this method are analyzed in the view of the effectiveness and applicability for the winding polarity discrimination.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.4
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• pp.510-519
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• 1998

Recently, computer modelling is increasingly used as a design tool, which requires more detailed data for heat transfer coefficients in various regions of the induction motor. But there are little information about those of rotor fan and endring because of difficulty in measuring signals in rotating bodies. In the present studies, the temperature signals were precisely measured with self-developed telemetry system, which had multi-channels and high rotational speed. After some losses were compensated, the heat transfer coefficients of the rotor endring and fan surfaces were measured. Minimum heat transfer region was existed with endcap plate distance and maximum heat transfer was found at some rotor fan width. It was also studied that how the guide plate and endcap inside rib effected on the rotor heat transfer. The higher heat transfer were obtained with decreasing guide plate distance, increasing the number and height of endcap inside rib. The correlation equations of the results were obtained and compared with others. Above results of the heat transfer coefficients can be used as basic data for cooling design of the various kind of motors.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1605-1609
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• 2007

In the case of Linear induction motor(LIM), numerical analysis method like Finite Element Method(FEM) has been mainly used to analyze the travelling magnetic field problem which includes the velocity-induced electromotive force. If the problem including the velocity-induced electromotive force is analyzed by FEM using Galerkin method, the solution can be oscillated according to Peclet Number, which is determined by conductivity, permeability, moving velocity and size of mesh. Consequently, the accuracy of the solution can be low and the Loops of flux can be occurred at the secondary back-iron. These loops of flux occurred at the secondary back-iron does not exist physically, but it can be occurred in the analysis. In this case, the loops of flux can be generally removed by using Up-Wind method which is impossible to apply a conventional S/W tool(Maxwell 2D). Therefore, in this paper, authors examined the Loops of flux occurred at the secondary back-iron of LIM according to variations of Peclet Number, and analyzed whether these loops of flux affect on the thrust force characteristics of LIM or not.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.705-706
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• 2008

There has been, in recent years, effort to make cast copper rotors for industrial use of induction motors. Because the incorporation of copper for the conductor bars and end rings of the induction motor in place of aluminum would result in attractive improvements in motor energy efficiency. The purpose of this method is a reducing the copper loss as using higher conductivity of copper. In this paper as the single phase induction motor is studied, the stator slots and coil turn number is designed for adjusting the slot fill factor and improving its efficiency. At this time design is basis on calculation of reducing loss. And finally this paper shows that the before and after result is compared and analyzed.