• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.24-26
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• 2004

The PM(Permanent Magnet) stepping Motor has been used widely to a variety of industries because of the open-loop control characteristic, a relatively large frequency range of velocity control and non-accumulated error of the step angle. Moreover, It has been gradually applied to office automation, machine intelligence, digital appliance, and automobile parts. This paper presents the optimal design results by use of the experimental method. The design variables of the PM stepping motor are shape of the claw-pole, material of core, and air-gap. As a result, a superior claw-pole PM stepping motor for OA machinery was developed.

• Journal of Korean Elementary Science Education
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• v.26 no.4
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• pp.440-448
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• 2007

The purpose of this study is to examine elementary students' conceptions of magnetic fields around various magnets by drawing tasks. A total of 105 elementary students from the 3rd and 6th grade levels were asked to draw how iron filings would arrange around magnets. We classified their drawings of magnetic field lines with some criteria to identify conceptions of magnetic forces and checked them through interviewing about their representative drawing. Through analyzing drawings, we discovered that 40% of elementary students drew the correct arrangement of iron filings around a bar magnet. In the case of two bar magnets in opposite directions, 33% of them drew correct patterns of iron dust and around two magnets in the same direction only 20% did well. Only 2.9% and 7.6% of students presented the correct drawings of magnetic fields near a disc and a horseshoe magnet. While 3rd grade students were supposed to be poor in drawings of magnetic fields around a loose and a dense coil which was not learned about, only 31% and 23% of 6th grade students who have just studied electromagnetism properly drew patterns of iron dust. This shows that only one quarter of students understood the magnetic filed lines even after instruction of electromagnetism. Many of 6th grade students learned a solenoid becomes just as a permanent magnet, but very few of them correctly drew a magnetic field line could distinguish between the iron dust around a loose and dense coil. After interviewing students, it is found that students consider magnetic forces to be existed only in parts of magnet because many of them drew magnetic field line of a specific areas around magnets. Students had misconceptions that magnetic forces exist only on the poles not in the middle around a horseshoe magnet. Also the disc-shape magnet made students to reveal various types of misconceptions: N- and S-poles are mixed in a whole magnet and right part of a disc-shape magnet is N-pole, left part is S-pole. Students who had not studied magnetic fields of around a magnet and electromagnets could not draw the correct patterns of iron dust suggest that it is indispensable for students to teach how patterns of iron filings would represent a visual image of magnetic fields in order to understand magnetic fields.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.4
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• pp.739-745
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• 2011

This paper proposes a method for reducing the negative spatial harmonics of the radial flux density of an interior-type permanent magnet (IPM) motor. The reliability of the motor is increased by minimizing its vibrations under dynamic eccentricity (DE) state and normal state due to reduction of a negative spatial harmonics component through the influx of a zero spatial harmonics component in the radial flux density. To minimize the vibrations, optimal notches corresponding to the distribution shape of the magnetic field are designed on the rotor pole face. The variations of vibration computation by finite element method (FEM) and the validity of the analysis and rotor shape design are confirmed by vibration and performance experiments.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.6
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• pp.872-877
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• 2015

The Permanent Magnet (PM) machine used at speed control using field-weakening control method. But the field-weakening current, which reduces the field flux for high speeds, causes significant copper and core losses. Therefore, this paper deals with the PM performance evaluations in a pole changing memory motor (PCMM). The PCMM can change the number of magnetic poles and produce two types of torque. When the motor operates with eight poles, it produces a magnetic torque at low rotational speeds. When the motor changes to four poles, it produces both magnetic torque and reluctance torque at high speeds. The paper explain the principle and basic characteristics of the motor by using a finite element method magnetic-field analysis, which consists of a PM magnetized by a pulse d-axis current of the armature winding. The results of our experiment show that the proposed motor reduces core loss by 10% and 55% under no-load and load conditions, and doubles the speed range of the motor.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.10
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• pp.1942-1946
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• 2009

This paper presents a shape design process of Claw-Poles Stepping Motor(CPSM) using Modified Magnetic Equivalent Circuit Method(MMEC). Because this motor is adopted on low power devices, the motor size is a very small type. But it have a very strong permanent magnet. So magnetic saturation effect happens on yoke teeth of CPSM. Also this magnetic saturation effect causes more leakage flux component between yoke tooth have another pole. In this motor type, it is essential to design a shape of yoke teeth for avoiding the magnetic saturation effect and the leakage flux. In this paper, MMEC including the magnetic saturation effect and the leakage flux component was used for design process. Comparing with data calculated by using the MMEC and results analyzed by 3-D FEM, it could be stated that the design process with MMEC was reasonable. Finally, the model has the optimized shape of yoke teeth was compared with a conventional model for no-load Back EMF and torque at steady-state operation.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.129-131
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• 2007

BLDC 모터의 진동 및 소음의 원인인 영구자석과 슬롯 개구부 형상에 의한 코깅토크를 저감시키기 위하여, RSM(Response Surface Method)과 FEM(Finite Element Method)를 이용하여 영구자석의 형상을 최적화 하였다. 최적화 과정은 총 2단계에 걸쳐 진행되었다. 1단계에서는 영구자석의 자극간격을 구하고, 2단계에서 자석의 형상을 변화시저 최적화한 결과, 최적화 전 후의 코깅도가, 최대 0.051[N.m]에서 0.029[N.m]로 약 50% 감소하였다.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.3
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• pp.120-126
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• 2005

This paper deals with a Double-type Transverse Flux Linear Motor which can be applied to high power system. This type can reduce overall system volume because it has a double flux path, and less number of phases and turns comparing with prototype for one phase. This machine is based on permanent magnet excitation, and the pole shape is designed to reduce attraction force between stator and mover poles. In the paper, the basic configuration of double type is introduced first, and the principle of movement is explained. After performing the characteristic analysis by 3-dimensional equivalent magnetic circuit network, the results are discussed.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.7
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• pp.320-326
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• 2003

Slotless Permanent Magnet Linear Synchronous Motor (PMLSM) has good control ability but thrust density is low. So, this paper proposes inserted core type of slotless PMLSM to improve its thrust density. Inserting the core between windings of each phase, detent force is generated by the difference of magnetic resistance in an air gap. To minimize detent force, this paper applies the neural network to inserted core type of slotless PMLSM. The, Magnetic pole ratio, the width of the inserted core and the width of the coil are selected as a design parameter to minimize detent force. In comparison with inserted core type one, thrust ripple greatly decreases by minimizing detent force and also thrust increases in this optimal model.

• Proceedings of the KIEE Conference
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• summer
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• pp.929-931
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• 2004

Recently, there are growing demands for permanent magnet(PM) type stepping motor that greater mechanical output, smaller size. Especially, the PM type stepping motor with claw-poles is preferred solution for many small electronics position determination devices since it is small in size, low cost. But, the design of the PM type stepping motor with claw-poles is very difficult because it has a magnetic 3-D shape. This paper deals with a study of the miniaturization of the PM type stepping motor with claw-poles. We investigate the characteristic of the actual model using the equivalent magnetic circuit method and 3-D FE analysis.

• Proceedings of the KIEE Conference
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• summer
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• pp.1052-1054
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• 2004

This paper deals with a Double type Transverse Flux Linear Motor(TFLM) which can be applied to high power system. This type can reduce overall system volume because of the configuration which has double flux path of prototype per phase, and less number of phase and turns. This TFLM is based on permanent magnet excitation, and the pole shape is designed to reduce attraction force between stator and mover poles. In the paper, the basic configuration of double type and the principle of movement are introduced. After performing the characteristic analysis by 3-dimensional equivalent magnetic circuit network, the results are discussed.