• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제11B권4호
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• pp.146-150
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• 2001

Comparison on the performances between the Halbach array type permanent magnet linear synchronous motor (HA-PMLSM) and the convensional array type permanent magnet linear synchronous motor (CA-PMLSM) was made with finite element analysis (FEA) and experiment. The HA-PMLSM is seen to be superior to the CA-PMLSM. Optimum ratio of magnet length to slot pitch of the HA-PMLSM which reduces the detent force was determined. Also, Comparison of forces of the HA-PMLSM and the CA-PMLSM with minimum detent force is presented.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권2호
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• pp.137-141
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• 2005

A transverse flux, PM-exited linear motor (TFM-LM) with inner mover was designed and built. Its output power density is higher and its weight is lower than those of the conventional PM exited linear synchronous motors (PM LSM). To obtain the maximum thrust force under the given volume, the thrust force density with respect to the ratio of the slot width and the length of pole pitch is analyzed by the 3-dimension finite element method (FEM). Finally, calculated static thrust forces was compared with the experimental values. The calculated and measured performance of the transverse flux, PM-exited linear motor with inner mover revealed great potential for system improvements by reducing the mass of the linear motor. For examples, when this motor was applied to a ropeless elevator, it was possible to increase the power density by more than 400% over the conventional PM-LSM. The results of this study recommend this type of motor for the ropeless elevator or gearless direct linear driving system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 추계학술대회 논문집 학회본부
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• pp.126-129
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• 1991

The effect of each tooth for optimal design of Hybrid permanent magnet step motor is presented on this paper. For this consideration, Hybrid permanent magnet step motor was designed in the first consideration tooth structure on the stator and the rotor and poles structure, as number of teeth on the stator and the rotor and slot depth and pitch of teeth, simulated by AutoLISP. During actual rotating, a chracteristic of Hybrid permanent magnet step motor which designed by AutoLISP program is considered. A chracteristic of Hybrid permanent magnet step motor is considered in change each variable, also. As a result, it was found that characteristic of Hybrid permanent magnet step motor changed in accordance with tooth structure and number of teeth and optimal design is possible by AutoLISP.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.194-196
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• 2006

This paper deals with design of a small-scaled permanent magnet generator (PMG) for wind power applications. First, this paper determines rated power and rated speed of the PMG from measured characteristics of wind turbines. Second, we derive analytical solutions for the open-circuit field in order to determine optimum magnet thickness and pole pitch/arc ratio. Third, on the basis of open circuit field solutions, stator magnetic circuit is designed. And then, a diameter of stator coil which agree with a required current density is calculated, and its turns are determined from the area of slot. Finally, finite element (FE) method is employed for validity of the designed PMG and, the back-emf measurements are also given to confirm the design.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권2호
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• pp.10-17
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• 2012

This paper presents an improved iron loss model, for the computation of the no load iron loss in the stator core of the in-wheel permanent magnet synchronous motors (PMSM), for the cases of with and without stator skew. 2-D analytical model is used for the computation of tooth and yoke flux densities of the in-wheel PMSM. The no load iron loss computed by the improved iron loss model, for the cases of with and without skew is compared with the finite element method (FEM) and the results show good consistency.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.33-35
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• 2002

This paper proposes the optimal design method to reduce the cogging torque of the interior permanent magnet motor using the design of experiment. The slot opening. tooth tips and the pole arc/pole pitch are chosen as factors of the design of experiment in order to find optimal conditions of the interior permanent magnet motor. Finally, the cogging torque of the optimized motor compares with that of the original motor.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제11B권2호
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• pp.1-8
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• 2001

This paper deals with magnetic field analysis and computation of cogging torque using an analytical method in Interior Permanent Magnet Motor (IPMM). The magnetic field is analyzed by solving space harmonics field analysis due to magnetizing and the cogging torque is analyzed by combining field analysis with relative permeance. In reducing cogging torque, the inferences of various design variable and magnetizing distribution are investigated. It is shown that the slot and pole ratio (the pole-arc / pole-pitch ratio) combination has a significant effect on the cogging torque and presents a optimal flux barrier shape to reduce the cogging torque. The validity of the proposed technique is confirmed with 2-D Finite Element(FE) analysis.

• 반도체디스플레이기술학회지
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• 제22권3호
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• pp.28-35
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• 2023

Moiré patterns emerge due to the interference between the non-emission area of the LED screen and the grid line in an image sensor of a video recording device when taking a video in the presence of the LED screen. To reduce the moiré intensity, we have fabricated an anti-moiré filter using hollow glass microspheres (HGMs) by slot-die coating. The LED screen has a large non-emission area because of a large pitch (distance between LED chips), causing more severe moiré phenomenon, compared with a display panel having a very narrow black matrix (BM). It is shown that HGMs diffuse light in such a way that the periodicity of the screen is broken and thus the moiré intensity weakens. To quantitatively analyze its moiré suppression capability, we have calculated the spatial frequencies of the moiré fringes using fast Fourier transform. It is addressed that the moiré phenomenon is suppressed and thus the amplitude of each discrete spatial frequency term is reduced as the HGM concentration is increased. Using the filter with the HGM concentration of 9 wt%, the moiré fringes appeared depending sensitively on the distance between the LED screen and the camera are almost completely removed and the visibility of a nature image is enhanced at a sacrifice of luminance.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.443-443
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• 2009

Cogging Torque is induced by the magnetic attraction between the rotor mounted permanent magnet(PM) and the stator teeth. This torque is an unwanted effect causing shaft vibration, noises, metal fatigues and increased stator length. A variety of techniques exist to reduce the cogging torque of PM generator. Even though the cogging torque can be vanished by skewing the stator slots by one slot pitch or rotor magnets, manufacturing cost becomes high due to the complicated structure and increased material costs. This paper introduces a new cogging torque reduction technique for PM generators that adjusts the azimuthal positions of the magnets along the circumference. A 900 kW class PMSG model is simulated using a three dimensional finite element method and the resulting cogging torques is analyzed using the Maxwell tensor stress tensor. Using the 3D simulation, the end contribution of the cogging torque is accurately calculated.

• 한국자동차공학회논문집
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• 제23권2호
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• pp.153-160
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• 2015

Hybrid Electric Vehicles(HEVs) have seriously come into prevalence recently as car manufacturers and consumers have become more aware of the environmental and economic problems of conventional vehicles. For the alternative power-train and battery cooling systems in HEVs, an effective thermal management system is required, and many automakers are interested in using Brushless DC(BLDC) motors for cooling fans for the overall traction unit's performance and energy saving capability. This paper presents the development status of BLDC motors as major parts of the power-train, i.e. the engine cooling and battery cooling fans of HEVs. A design that uses BLDC motors for the power-train and each battery cooling fan, is successfully implemented through using electro-magnetic analysis, and prototype BLDC motors are examined. As experimental results, the BLDC motors achieved an efficiency of 85% as engine cooling fans and 72% as a battery thermal management fan motor. The electric cogging noise is significantly reduced by changing the skew of the slot pitch angle and optimizing the magnetic shape.