• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.7
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• pp.1231-1235
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• 2007

This paper presents the dynamic characteristics of a linear brushless dc (BLDC) motor with permanent magnet excitation for the precision conveyor according to the load condition. Dynamic performance of the linear BLDC motor driven with 6 step inverter such as thrust force and speed is simulated by finite element method coupling with external circuit and measured for the prototype motor. The results of finite element analysis are compared to the experimental results and verify reliability.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.771-773
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• 2001

In this paper, three dimensional Equivalent Magnetic Circuit Method(3-D EMCN method) a numerical analysis method which supplements to magnetic equivalent circuit adding numerical technique, is proposed for analysis Optical Pickup Actuator. (3) This method provides better characteristics both in precision of the analysis and in computation time than other analysis method such as three-dimensional Finite Element Method. We choose the simple 2-magnet moving coil type pickup actuator model and verify upper yoke effect using this method.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.723-725
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• 2001

Ion plating method using plasma is faster as several times than electron beam plating method in plating process. Recently, a variety of techniques for this method are being researched. In this paper to produce sheet plasma with high density for ion plating we designed magnetic circuit of MgO plating device consisting of solenoid coil, rectangular permanent magnet. And, we researched on the effect of those by analyzing magnetic field distribution using FEM.

• Journal of Magnetics
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• v.20 no.4
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• pp.432-438
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• 2015

This paper presents an electromagnetic analysis of a tubular linear machine with axially magnetized permanent magnets using improved analytical techniques. Based on the magnetic vector potential and a two-dimensional polar-coordinate system, the magnetic field and armature reaction field can be derived. Using these, equivalent circuit parameters, such as the electromotive force and inductance, can be obtained analytically. Finally, the generating characteristics are derived with the equivalent circuit method. In this study, the finite element method was employed to provide a comparative evaluation, and experiments were conducted to validate the results of the analytical analysis.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.1
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• pp.1-7
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• 2004

This paper presents a sensorless control strategy of a PMSM(Permanent Magnet Sycchoronous Motor). This method is very simple to compute the position angle of a rotor. A principle and a practical solution are described. A sensorless control algorithm is proposed to remove a mechanical position sensor. The theory is based on the superposition principle. The state equation of a motor is divided into two conditions: one is the state equation of exciting voltage and phase current in a constraint, the other is the state equation of back EMF(Electromotive Force) and phase current in a short circuit. Based on the analysis, short circuit current by back EMF is computed and then the information of position angle is calculated. The proposed method is verified by experimental results.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.18-20
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• 1999

In this paper, the space mapping algorithm is proposed for the design of electric machines. By the algorithm, we can combine the magnetic equivalent circuit and the finite element models mathematically and got the final design parameters with a few iterations while preserving the accuracy offered by the finite element model. The finite element model is generated by parametric techniques. For the validity of this algorithm, a simple permanent magnet device with fringing and leakage flux is dealt as a numerical example.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.876-878
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• 2000

In this paper, the characteristic of the Linear DC motor(LDM) are analyzed by using 3 Dimensional Equivalent Magnetic Circuit Network (3D EMCN), the movement of mover substitutes for the movement of magnetization in permanent magnet expressed by Fourier series, thrust characteristic analysis is performed and the appropriateness of analysed result is verified by comparing with the results of 2 Dimensional Finite Element Method (2D FEM) and experiment.

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.76-76
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• 2002

Purpose： The purpose of this study is to optimize the configuration of body RF coil composed of 4 planar subcoils for low field open MRI. Method： Our low field RE coil is composed of 4 subcoils assumed to be located at both the bottom and top sides of permanent magnet. Each subcoils has 3 main strips. The coil system has mirror inversion symmetry. First, the currents on the strips are obtained by inductance calculation and circuit analysis, Second, all the strips are divided into line strip elements across the strips, the self Inductances of line strip elements and the mutual inductances among the line strip elements are calculated, and current distributions of strip are obtained by circuit analysis, where each strip is considered as parallel combination of line strip elements. Finally all the line strip elements are segmented, magnetic field has been calculated by pseudo electric dipole radiation method, where the current elements are regarded as pseudo electric dipole radiation sources. We have performed above procedures for various configurations of RE coil. The field homogeneity is calculated in the 25 cm DSV.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.4
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• pp.135-143
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• 1985

The failure and erosion of relay contacts mainly depend on the presence of particles deposited on the contact surface in various contaminated atmospheres. In this paper, the effects of sea water and circuit parameters on the arcing and quenching of magnet relay contacts are studied. The sea water pollutants of relay contact surface have led to increase the arcing numbers on making contact, and the mean arc durations on breaking contacts. Moreover, the maximum surge voltage and mean arc duration between relay contacts are also varied significantly by the circuit parameters. The effects of the spark quenching circuits using condenser of diode on the arcing of contacts are also discussed.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.8
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• pp.381-389
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• 2003

Nowadays, Vacuum Circuit Breaker(VCB) is used in the most medium voltage level because vacuum has environment-friendly characteristics as well as excellent dielectric strength. In order to elevate the breaking performance, the improvement of vacuum interrupters and the driving mechanism should be proceeded. In this paper, the development of a Permanent Magnet Actuator could replace the mechanical spring mechanism which is the driving mechanism of existing VCB. The holding force and opening characteristics of magnetic actuator are analysed with FEM and the result is verified through experiment.