• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.117-119
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• 2005

This parer presents the application of response surface methodology (RSM) to design optimization for two types of synchronous reluctance motors (SynRMs) one has 12 slots with distributed winding, and the other has 6 slots with concentrated winding, to improve the ratio between torque ripple and average torque. The usefulness of RSM in optimization problem of SynRM is verified as compared with the results of finite element analysis. In the end, the optimized two SynRMs are compared with SynRM currently used in air-conditioning compressor in connection with torque performance and loss.

• Journal of the Korean Society for Railway
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• v.15 no.2
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• pp.135-140
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• 2012

Interior Permanent Magnet Synchronous motors (IPMSM) with concentrated winding are superior to distributed winding in the power density point of view. But it causes huge amount of eddy current losses on the permanent magnet. This paper presents the optimal permanent magnet V-shape on the rotor of an interior permanent magnet synchronous motor to reduce the core losses and improve the performance. Each eddy current loss on permanent magnet has been investigated in detail by using FEM (Finite Element Method) instead of equivalent magnetic circuit network method in order to consider saturation and non-linear magnetic property. Simulation-based design of experiment is also applied to avoid large number of analyses according to each design parameter and consider expected interactions among parameters. Consequently, the optimal design to reduce the core loss on the permanent magnet while maintaining or improving motor performance is proposed by an optimization algorithm using regression equation derived and lastly, it is verified by FEM.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.329-330
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• 2014

This paper presents an analysis of the interleaved effects for the secondary winding distribution of a toroidal transformer. The equations to calculate the leakage inductance are derived using the MMF diagram for the distributed secondary windings. The simulation and experimental results are provided to show the effect of the leakage inductance reduction.

• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1352-1364
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• 2013

This paper describes a novel structure for single phase Unified Power Quality Conditioner-Distributed Generation (UPQC-DG) with direct grid connected DC-AC converter for low DC output DG systems which can be used not only for compensation of power quality problems but also for supplying of load power partly. This converter has been composed of one full-bridge inverter, one three winding high frequency transformer with galvanic isolation and two cycloconverters. Proper control based on Input Output feedback Linearization is used to tracking the reference signals. The simulation and experimental results are presented to confirm the validity of the proposed approach.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.65-67
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• 2001

In general, the results of finite element method(FEM) on the analysis of the electrical machines has known as high accuracy but required very long time to calculate the field distribution. Magnetic equivalent circuit(MEC) method can be computing times less than the finite element method and also it provides steady state and transient state simulation. In this paper, describes matrix representation of the winding magneto motive force(MMF) and carry out the distributed the airgap magnetic density takes into account the influence on the stator slots.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.577-582
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• 2020

Electricity produced at power plants is distributed to consumers through several stages of substations. At this time, an ultra-high voltage transformer is needed in the initial transmission stage to transmit a voltage suitable for each consumer. A high voltage, non-uniform electric field is formed at the end of the winding of the ultra-high voltage transformer, which carries a risk of dielectric breakdown. The winding of the ultra-high voltage transformer is an electrode, which is the key to converting the magnitude of the voltage. A non-uniform electric field is formed along the shape of the winding end, resulting in high electrical stress. The static ring installed at the upper and lower ends of the winding is used to disperse the stress at the winding end. Several variables should be considered when designing a static ring. Among them, this study examined how the curvature of the static ring, the thickness of the insulating paper, the number of barriers, and barrier thickness affect the electrical stress of the static ring using the Finite Element Method. Suggestions to be considered when designing the static ring are proposed through the FEM results.

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.1956-1964
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• 2018

Since the stator winding of High-Speed Permanent Magnet Generator (HSPMG) has few winding turns and low inductance value, it is more prone to be influenced by harmonic current. Moreover, the operation efficiency and the torque stability of HSPMG will be greatly influenced by harmonic current. Taking a 117 kW, 60 000 rpm HSPMG as an example, in order to analyze the effects of harmonic current on HSPMG in this paper, the 2-D finite element electromagnetic field model of the generator was established and the correctness of the model was verified by testing the generator prototype. Based on the model, the losses and torque of the generator under different frequency harmonic current were studied. The change rules of the losses and torque were found out. Based on the analysis of the influence of the harmonic phase angle on torque ripple, it is found that the torque ripple could be weakened through changing the harmonic phase angle. Through the analysis of eddy current density in rotor, the change mechanism of the rotor eddy current loss was revealed. These conclusions can contribute to reduce harmonic loss, prevent demagnetization fault and optimize torque ripple of HSPMG used in distributed power supply system.

• Progress in Superconductivity and Cryogenics
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• v.23 no.4
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• pp.44-48
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• 2021

In order to obtain ultra-high resolution MRI images, research and development of 11 T or higher superconducting magnets have been actively conducted in the world, recently. The high-temperature superconductor (HTS), first discovered in 1986, was very limited in industrial application until mid-2010, despite its high critical current characteristics in the high magnetic field compared to the low-temperature superconductor. This is because HTS magnets were unable to operate stably due to the thermal damage when a quench occurred. With the introduction of no-insulation (NI) HTS magnet winding technology that does not burn electrically, it could be expected that the HTS magnets are dramatically reduced in weight, volume, and cost. In this paper, a 6 T-class NI HTS magnet for basic characteristic analysis was designed, and a distributed equivalent circuit model of the NI coils was configured to analyze the charging current characteristics caused by excitation current, and the charge delay phenomenon and loss were predicted through the development of a simulation model. Additionally, the critical current of the NI HTS magnets was estimated, considering the magnetic field, its angle and temperature with a given current. The loss due to charging delay characteristics was analyzed and the result was shown. It is meaningful to obtain detailed operation technology to secure a stable operation protocol for a 6T NI HTS magnet which is actually manufactured.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.867-869
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• 2002

A method for the time step analysis of single phase induction motors is proposed. The unknown variables in differential equations are the currents flowing through rotor bars. They are coupled with the distributed magnetic flux densities in the airgap instead of inductance matrix while applying Kirchhoff's and Faraday's induction laws. Two patterns for magnetic flux densities are necessary. One is given by ideal stator winding distribution. the other is produced by currents flowing a rotor bar with unit magnitude and is calculated by FEM. Formulated set of equations are solved for a simple three phase and single phase example model and the resultant speed torque curve is shown in this paper.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.816_817
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• 2009

Optimization of geometry is one of the most important design process of the electrical motors. Tooth and yoke width are important variables that can maximize back emf and load torque among various design parameters. In this paper, in order to design the tooth and yoke width effectively, an equivalent magnetic circuit of one pole is constructed and an optimal value of tooth and yoke width resulting minimum reluctance are determined instead of a finite element analysis(FEA) that is time consuming.