• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.455-458
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• 2001

This paper presents an axial flux permanent magnet synchronous generator with a high power-to-weight ratio, dedicated for small-scale gearless wind power generation plants. For this purpose, a specific design is necessary to meet the imposed requirements. In this paper the design technique for the specifications is presented. The aim of the paper is also to discuss some of the first obtained test results and the involved demagnetizing problem (i.e. short-circuit).

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.12
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• pp.1255-1260
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• 2004

A moving-magnet type pickup actuator has an assembly error. That is, the actuating Part of an actuator is shifted from initial position after we assemble it into yoke. This Is the result of an effect of magnetic force between magnet and yoke. We performed magnetic-analysis using FEA. As a result of simulation, we improved the assembling efficiency for moving-magnet type actuator.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.356-361
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• 2004

A moving-magnet type pickup actuator has an assembly error . That is, the actuating part of an actuator is shifted from initial position after we assemble it into yoke. This is the result of an effect of magnetic force between magnet and yoke. We performed magnetic-analysis using FEA. As a result of simulation, we improved the assembl ing efficiency for moving-magnet type actuator.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.6
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• pp.273-281
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• 2001

In order to overcome the demerit and to improve the operation characteristics of Moving Coil type Linear Oscillatory Actuator(MC-LOA) with single-pole permanent magnet, this paper presents two models having the balanced magnetic circuit by multi-pole permanent magnet. They are short coil type with two-pole single-sided and two-ple double-sided permanent magnet. The characteristics between single-pole and multi-pole permanent magnet type MC-LOA are compared. As a result, multi-pole type MC-LOA has more merits than single-pole type about operation characteristics improvement and machine volume. The characteristics analysis is performed by their dynamic analysis composed of kinetic and electric equations and Finite Element Method(FEM). The propriety of multi-pole type MC-LOA model is verified with analysis results.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.2
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• pp.81-87
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• 2005

The torque characteristics of permanent magnet(PM) motor is varied according to magnet width. In this paper, the design method of magnet and magnetic circuit is proposed in order to improve the torque of Interior Permanent Magnet Synchronous Motor(IPMSM). This paper presents the effects of pole arc ratio and salient pole ratio on the torque and torque ripple in the IPMSM with concentrated winding.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.8
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• pp.514-521
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• 2000

This paper presents a direct thrust control scheme for permanent magnet linear synchronous motor(PMLSM) by using digital signal processor(DSP). And a simulation method for the direct thrust control of a permanent magnet linear synchronous motor using the equivalent circuit is presented. The detent force that was obtained by cubic spline method is considered in the simulation. Thrust correction coefficient is utilized to estimate actual thrust on the direct thrust control, which considers the longitudinal end effect due to the finite core length of the permanent magnet linear synchronous motor. The motor self inductance, the initial flux linkage by the permanent magnet is calculated in advance by the finite element analysis, and then the direct control simulation is carried out. As the results, thrust, current and speed are shwon.

• Proceedings of the KIEE Conference
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• 2007.04c
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• pp.56-58
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• 2007

This paper deals with analytical prediction for the cogging torque of permanent magnet machines with multi-pole rotor First. open-circuit field solutions are derived using a magnetic vector potential and a two-dimensional (2-d) polar coordinate systems. On the basis of derived open-circuit field solutions and 2-d permeance functions. we also derive the analytical solutions for the open-circuit field considering stator slotting effects and cogging torque. All analytical results are shown in goof agreement with those obtained from finite element (FE) analyses.

• New & Renewable Energy
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• v.2 no.3
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• pp.10-14
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• 2006

We have designed and fabricated coil structures by gold electroplating technique. The thickness, width, and length are $7{\mu}m,\;20{\mu}m$, and 1.6m, respectively. With vibrating a magnet on the surface of a fabricated electroplated coil, the micro power generator produce an alternating voltage. We have changed the vibrational frequency from 0.5Hz to 8Hz. The generated voltage was 106mV at 3Hz and 198mV at 6Hz. We have rectified and stepped up the input voltage using a quadrupler circuit. After using the step up circuit, the measured voltage was 81mV at 3Hz and 235mV at 6Hz.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.41-43
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• 2001

We studied on effective quench protection method to prevent damage from unexpected quench of the inductively coupled superconducting magnet systems for magnetic resonance imaging. And we suggested quench protection circuit that is combined with several protection techniques. This circuit has the capacity to maintain the symmetric nature of the magnetic field and the active shielding effect and to protect shim coils during a quench.

• Progress in Superconductivity and Cryogenics
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• v.3 no.2
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• pp.15-20
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• 2001

This paper describes a model flux pump experiment recently performed at the MIT Francis Bitter Magnet Laboratory. The results of the model flux pump will be used in the development of a prototype flux pump that will be couple to a high-temperature superconductor (HTS) insert coil of a high-field NMR (Nuclear Magnetic Resonance) magnet, Such an HTS insert is unlikely to operate in persistent model because of the conductors low index(n) The flux pump can compensate fro field decay in the HTS insert coil and make the insert operate effectively in persistent mode . The flux pump, comprised essentially of a transformer an two switches. all made of superconductor, transfers into the insert coil a fraction of a magnetic energy that is first introduced in the secondary circuit of the transformer by a current supplied to the primary circuit. A model flux pump has been designed. fabricated, and operated to demonstrate that a flux pump can indeed supply a small metered current into a load superconducting magnet. A current increment in the range of microamperes has been measured in the magnet after each pumping action. The superconducting model flux pump is made of Nb$_3$ Sn tape, The pump is placed in a gaseous environment above the liquid helium level to keep its heat dissipation from directly discharged in the liquid: the effluent helium vapor maintains the thermal stability of the flux pump.