• Progress in Superconductivity and Cryogenics
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• v.21 no.3
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• pp.43-46
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• 2019

A rare-earth barium copper oxide (REBCO) superconducting magnet was designed using no-insulation (NI) and multi-width (MW) winding techniques. The proposed magnet is comprised of 58 REBCO-wound single pancake coils with a bore size of 240 mm. When the magnet is operated at 20 K, the center magnetic flux density is designed to reach 3 T with an operational current of 169.55 A, 70 % of its critical current. The critical current was evaluated using experimental data of a short REBCO conductor sample. The designed magnet was then simulated using FEM software with uniform current density model. Magnetic field and mechanical properties of the magnet are evaluated using the simulated data. This magnet was designed as one of the base designs for the project "Tesla-Level Magnets with Large Bore Sizes for Industrial Applications" which was initiated in 2019, and will be wound using REBCO wires with the defect-irrelevant-winding (DIW) technique incorporated to reduce the overall manufacturing cost.

• Journal of Electrical Engineering and Technology
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• v.10 no.2
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• pp.545-550
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• 2015

High Temperature Superconducting (HTS) synchronous generators can be designed with either an air-core type or iron-core type. The air-core type has higher efficiency under rated rotating speed and load than the iron-core type because of the iron losses which may produce much heat. However, the total length of HTS wire in the air-core type is longer than the iron-core type because the generated magnetic flux density of the air-core type is low. This paper deals with designs of 10 MW air-core and iron-core HTS wind power generators for wind turbines. Fully air-core, partially iron-core, and fully iron-core HTS generators are designed, and various stator winding methods in the three HTS generators are also considered, such as short-pitch concentrated winding, full-pitch concentrated winding, short-pitch distributed winding, and full-pitch distributed winding. These HTS generators are analyzed using a 3D finite elements method program. The analysis results of the HTS generators are discussed in detail, and the results will be effectively utilized for large-scale wind power generation systems.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.30-32
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• 1995

The model interrupters of $SF_6$ gas electromagnetic contactor whose ratings are the voltage of 7.2kV and the short circuit current of 4.0kA have been designed and manufactured on the basis of theoretical and computational analysis for its development. The eddy current analysis, the magnetic field analysis and the calculation of the rotational force on arcs have been conducted using FLUX2D package. The short circuit current interrupting tests have been conducted to the model interrupters using the simplified capacitive synthetic test circuit in KERI. The results show that the model interrupters have a sufficient interrupting capability and the new design concept is proper for a good interrupting performance.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.77-79
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• 1996

The model interrupters of $SF_6$ gas electromagnetic contactor whose ratings are 7.2kV, 4.0kA have been designed and manufactured on the basis of theoretical and computational analysis for its development. The eddy current analysis, the magnetic field analysis and the calculation of the rotational force on arcs have been conducted using FLUX2D package. The short circuit current interrupting tests have been conducted for the model interrupters using the simplified synthetic testing facility in KERI. The results show that the model interrupters have sufficient interrupting capability and the new design concept is prefer for good interrupting performance.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.3
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• pp.347-353
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• 2012

Design and analysis of a novel 2-phase 4/5 Switched Reluctance Motor(SRM) is presented. The proposed motor employs a novel stator pole configuration. A novel SRM employs four-rotor and five-stator poles. The motor has no dead-zone and can be operate at any rotor position. The structure and operating principle are also described. The comparison between the proposed motor and a conventional two-phase 4/2 SRM is undertaken in this analysis. Furthermore, the Finite Element Analysis(FEA) and matlab-simulink are used to predict and simulate the performance of a proposed motor. The results of investigation indicate that the proposed structure offers a better performance in term of torque production.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1048-1050
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• 2003

Recently, many linear motion generators and motors are rapidly finding applications that ranges from short stroke linear motion vibrators, such as dynamic con type loud speakers to stilting engine driven linear reciprocating alternators, compressors, textile machines etc. In this paper, we analyze the characteristics of tubular linear motor with Halbach and radial magnet array respectively. We already derived magnetic field solutions due to the PMs and to the currents and Motor thrust. On the basis of analytical field solutions, this paper deals with flux linkages and back emf. The results are validated extensively by comparison with finite element analyses. Then, this parer also presents thrust characteristics according to design parameters for each model.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.5
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• pp.423-430
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• 2009

Recently as the inactive response characteristics of the existing RCD used on low voltage power distribution system, so control of overload and electric short circuit faults, major causes of electrical fires, are not enough. Therefore, this paper confirms the unreliability of the existing RCD by electrical fault simulator and proposes a EFDPD by using semiconductor switching devices and a high precision current sensor (namely, reed switch) for the prevention of electrical disasters in low voltage power distribution system caused by overload or electric short circuit faults. The sensitive reed switch in the proposed EFDPD exactly detects the increased magnetic flux with the overload or the short current caused by a number of electrical faults, and the following, the self circuit breaker in EFDPD rapidly cuts off the system. The proposed EFDPD confirms the excellent characteristics in response velocity and accuracy in comparison with the conventional circuit breaker through various operation performance analysis. The proposed EFDPD can also prevent electrical disasters, like as electrical fires, which resulted from the malfunction and inactive response characteristics of the existing RCD.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.5
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• pp.241-248
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• 1999

Recently, many linear motion generators and motors are rapidly finding applications that ranges from short stroke linear motion vibrators, such as dynamic cone type loudspeakers to stirling engine driven linear reciprocating alternators, compressors, textile machines etc. The stroke-length may go up to 2m, and the maximum speed is in the range of 5 to 10m/s with oscillating frequency as high as 15 kHz. Therefore, the linear oscillating actuators(LOAs) may be considered as variable speed drivers of precise controller with stoke-length and reversal periods during the reciprocating motion. In this paper, the design, fabrication, experiments, and extraction of control parameters of a moving coil type LOA for driving of linear reciprocating motion control systems, are treated. The actuator consists of the NdFeB permanent magnets with high specific energy as the stator produced magnetic field, a coil-wrapped nonmagnetic hollow rectangular bobbin structure, and an iron core as a pathway for magnetic flux. Actually, the design is accomplished by using FEM analysis for the basic configuration of a magnetic circuit, and characteristic equations for coil design. In order to apply as the drivers of a linear motion reciprocating control system, the control parameters and circuit parameters, such as input voltage-stoke, exciting frequency-stoke, coil inductance and so on, are extracted from the analysis and experiments on concerning a fabricating LOA.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.3
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• pp.206-212
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• 2017

Induction motor torque is the reactive power is needed which corresponds to the exciting current to generate the magnetic flux as the product of current and flux. For use in the method of supplying the required reactive power to the induction motor power factor correction apparatus using a lot of ways to supply in place of the power supply side, when using a power factor compensation device can reduce the apparent power, the power factor can be improved. However, the distance to the emergency generator transformers or motors from the motor capacity is smaller but short and difficult to maneuver the theory and practice of the operating characteristics of the starting characteristics of the motor used a lot of large industrial plants were measured and analyzed. Therefore, this study investigated the motor starting Analysis and interpretation for the relationship with the large motor starting torque and speed during motor starting.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.343-345
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• 2002

The influence of starting precursor powders on the phase formation and transport properties of Bi-2223/Ag tapes has been studied. The experimental results show that the average particle size of precursors as fine as 1.64 ${\mu}{\textrm}{m}$ and 1.51 ${\mu}{\textrm}{m}$ can still increase the transport properties. The J$_{c}$-B behavior is also enhanced in tapes fabricated with powders in finer particle sizes. However, at higher magnetic fields, J$_{c}$ of tape started from the powder with the finest particles drops rapidly at the direction of H//c, which is possibly attributed to the small grain sizes and weak flux pinning ability that due to the short induction period at the initial stage of phase formation as the result of fine particles in precursor powder.der.