• Journal of Electrical Engineering and Technology
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• v.1 no.4
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• pp.461-465
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• 2006

This paper presents a useful and simple method to design the passive skimming system for homogeneous permanent magnets based on numerical optimization. To simulate the effects of manufacturing and assembling tolerances, the actual geometrical parameter of the magnet with a derivation is suggested. Then, the optimal design model oi a passive shim system is set up to correct the derivative of field homogeneity. The numbers, sizes and locations of the passive shims are optimized by the steepest descent algorithm combined with design sensitivity analysis. Two implementations show that the proposed method can achieve the required homogeneity of the field with the minimum quantity of ferromagnetics.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.22-24
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• 2005

This paper is intended to introduce a set of static and dynamic experiments for a better characterization of the linear permanent magnet oscillatory machine. The experiment have been peformed on two prototypes; one with buried permanent magnets with flux concentration while the other with surface permanent magnets. Though the testing arrangement allows for it, temperature, noise and vibration have not been in this paper.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.888-892
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• 2014

In the design of the rotor of an interior permanent magnet synchronous motor (IPMSM), the bridge between the permanent magnets helps prevent the scattering of permanent magnets and pole pieces during high-speed operation. In the design of a motor, if the bridge is too thick, its performance will be largely degraded because of flux leakage. Additionally, if the bridge is too thin, its mechanical safety cannot be guaranteed. Thus, an accurate analysis method is required to determine the thickness of the bridge. Conventional stress analysis methods determine the thickness of the bridge by only considering the centrifugal force of the rotors. In this study, however, a method that additionally considers the radial force generated by the air-gap flux density based on the conventional methods is proposed and reflected in the design of a traction motor for electric vehicles. Finally, the validity of this study is verified through a reliability test related to high-speed operation.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1003-1004
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• 2007

This paper deals with the PM performance evaluations in a variable flux memory motor (VFMM) using a coupled finite element method (FEM) and Preisach modeling, which is presented to analyze the magnetic characteristics of permanent magnets. The focus of this paper is the operation characteristics evaluation relative to magnetizing direction and quantity of permanent magnets on redemagnetization condition in a variable flux memory motor(VFMM).

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1613-1615
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• 2005

Maglev equipped with permanent magnets on the moving part can be levitated by the magnetic repulsion between Halbach array and conducting plate when this vehicle is running. This paper deals with the fundamental principles of the eddy-current magnetic repulsion system and the force characteristics to the change of the permanent magnet array and conduction bar.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.11
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• pp.199-207
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• 1998

This paper presents the design and the control of three degree-of-freedom(DOF) fine positioning device based on an electro-magnetic force. The device is designed by use of a magnetic circuit theory and it is capable of fine motion due to the electro-magnetic force. The device consists of permanent magnets, yokes and coils. The magnetic fluxes generated from the permanent magnets constitute magnetic paths through steel, whereas the coils are arranged into the gap between two surfaces of the yokes. Therefore, by supplying current to the coils, the coils are capable of some motions due to Lorentz forces. For the optimal design of the actuating system, the system parameters are defined and investigated under the given constraints. From the system modeling in small displacement, three decoupled equations of motion are obtained. To get better performance of the system, a PID controller is implemented. Experimental results are presented in terms of time response and accuracy.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.12
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• pp.1101-1106
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• 2004

Magnetic refrigeration is based on the magnetocaloric effect (MCE)-the ability of some materials to heat up when magnetized and cool down when demagnetized. A rotary magnetic refrigeration device using gadolinium (Gd) ribbon and permanent magnets was constructed for experimental study. Gd ribbon attached around a rotating wheel is cyclically magnetized and demagnetized by permanent magnets and exchanges heat with liquid in the surrounding container. Temperature of the liquid in each divided section of the container was measured and the experimental results obtained in this study were discussed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.3
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• pp.122-128
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• 2021

Machining operations require removal of chips to keep the coolant clean and fresh throughout the operation time. In this study, microchip removal equipment was developed using AutoCAD and CATIA programs for 3D modeling and 2D draft. In addition, the flow analysis and electromagnetic field analysis of the equipment were performed using the COMSOL Multiphysics program. The flow design of the coolant oil tank was realized on the basis of fluid analysis results. Further, on the basis of magnetic density analysis, a conveyer was designed for effectively removing metal microchips in the tank by using arrays of neodymium permanent magnets.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.2_2
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• pp.325-332
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• 2024

Contemporary power systems demand efficient and sustainable technologies. Single-phase induction motors, while widely used, face efficiency challenges due to inherent rotor losses. Proposed solutions include the Line-start Permanent Magnet Synchronous Motor (LSPMSM), leveraging permanent magnets for enhanced energy density but facing demagnetization and cost issues. Alternatively, the Line-start Synchronous Reluctance Motor (LSRM) operates as a hybrid motor without permanent magnets, reducing rotor losses and potentially improving efficiency. This paper focuses on designing an LSRM rotor for air conditioner compressors, analyzing start-up characteristics and efficiency through finite element analysis. A comparative study with single-phase induction motors provides insights for future motor technology selection, balancing efficiency and other requirements.

• Journal of Magnetics
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• v.16 no.3
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• pp.304-307
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• 2011

High performance Nd-Fe-B magnets can be manufactured by both sintering and hot deformation. The corrosion behaviors of the magnets prepared by the two processes were compared. Effect of microstructure on the corrosion resistance of Nd-Fe-B magnets was also investigated. A neutral salt spray test (NSS) was performed for the different-processed magnets. The weight losses of the samples after the corrosion test were measured. The corrosion microstructures were observed using a scanning electron microscope. It shows that the corrosion resistance of hot deformed magnets is much better than that of the sintered ones because the grain size and the distribution of Nd-rich phases of the hot deformed magnets are much finer and more uniform than those of the sintered ones. The different microstructure between the sintered and the hot deformed magnets causes the different corrosion behavior.