• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.11
• /
• pp.2035-2042
• /
• 2011

In this paper, we proposed the outer-rotor type of FSPM motor for high speed operation and optimized motor shape. First of all, combinations of pole and slot numbers are examined for the optimal back-EMF and cogging torque, then optimizes the better shape design of the permanent magnet, rotor pole width. Further, The winding turns are obtained by circle of the voltage limit equation and motor parameters to minimize the current and to improve the efficiency. As a result, the performance of the designed model is satisfied, and it is verified through a two-dimensional finite element method (2D-FEA).

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.2
• /
• pp.309-314
• /
• 2011

Outer rotor type in-wheel switched reluctance motor for Welfare neighborhood electric vehicle is researched. In-wheel system is to drive the electric vehicle without mechanical transmission, shaft, differential gears or other mechanical system. To calculate drive power for each wheels, the elder's and disable's safety driving conditions are considered. The designed outer rotor SRM has a 6-stator and 8-rotor pole. The determined dimensions as well as the stator and rotor pole arc are simulated and tested with CAD and finite element analysis to verify the performance of the proposed motor.

• Proceedings of the KIEE Conference
• /
• 2009.04b
• /
• pp.64-66
• /
• 2009

소형 다상 의전형 BLDC 전동기의 코깅토크를 최소화하기 위해 코깅토크의 발생원인 중 하나인 고정자 슬롯의 형상에 샘플링 포인트 기법인 LHS를 이용한 최적화 알고리즘을 적용하여 코깅토크를 최소화하는 최적 설계를 수행 하였다. 총 3번의 반복계산을 하여 코깅토크가 최소화 되는 최적점을 계산한 결과, 최대 코깅 토크가 1.07 [N.m]에서 0.75 [N.m]로, 초기 형상의 약 70%로 감소되었다.

• Proceedings of the KIPE Conference
• /
• 2001.07a
• /
• pp.22-24
• /
• 2001

This paper presents the characteristics of current harmonics and torque ripple of Brushless DC motor, which is developed the fan blower of vehicles, according to input voltage waveform. To investigate the torque ripple and the phase current harmonics, these characteristics is analysed and compared the experimental results. In the process of analysis, FEM is introduced and computed a transient state torque of BLDC with a sinusoidal and a PWM wave voltage.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.1015-1016
• /
• 2007

원격 전력 시스템의 요구 증가로 인해 작고 효율적이며 경제성도 우수한 풍력 발전기의 시장이 확대되고 있다. 이러한 응용 분야를 위해서 최근 들어 직접 구동 영구자석 발전기에 많은 관심을 가지게 되었다. 본 논문에서는 유한요소해석을 이용한 저속, 고토크의 외전형 직접 구동 영구자석 풍력발전기 개발을 위한 설계 모델을 제안하였다. 여기서 발전기의 코깅 토크의 분석을 통하여 기동 토크를 최소화하는데 대한 연구를 수행하였다. 또한 역기전력과 동기리액턴스, 효율을 계산하였다. 설계 모델을 토대로 3kVA, 90rpm의 풍력발전기 시제품을 제작하였다. 마지막으로 시제품의 성능 시험 결과를 통하여 해석모델의 정확성을 증명하였다.

• Proceedings of the KIEE Conference
• /
• 1995.07a
• /
• pp.86-88
• /
• 1995

Outer-rotor type brushless motor is designed to run at more constant speed because of large inertia comparing with inner-rotor type. The constant speed is acquired by increasing inertia. Also, the generating torque is proportional to the rotor volume, i. e. rotor diameter. The main idea in this study is to design and analyze the outer-rotor type brushless motor by permeance method with given outer dimension.

• Childhood Kidney Diseases
• /
• v.1 no.2
• /
• pp.151-154
• /
• 1997

Purpose : The prevalence of renal malformation in Turner syndrome has been quoted as being greater than 50% in older series. Recently in 1988, Lippe's review gave a prevalence of 33%, significantly lower than all previous reports. In 1996, Flynn reported that renal malformation occurs in approximately 24% of all girls with Turner syndrome, and that it is seldom seen in girls with mosaic karyotype who form the predominant subgroup. The aim of this study was to evaluate prevalence of renal malformation by karyotype in Turner syndrome in Korea. Method : We evaluated 81 patients with Turner sundrome diagnosed in Yonsei University from Jan. 1987 to Dec. 1996. The patient entered in this study were those for whom both karyotype and ultrasound examination of the kidney were available. Result : 1) The karyotype showed: 45,X ; 29 cases (38%), mosaicism : 32 cases (40%), structural aberration ; 17 cases (22%). 2) Of the 29 cases of pure 45,X karyotype, 5(17%) had abnormal renal findings, while these were found in only 1 of the 30 mosaic cases(3.3%), and in 1 of the 17 structural aberration cases(6%). The malformation included 3 cases of horseshoe kidney, 2 cases of axial malrotation, hypoplastic kidney and simple cyst each one. There was no statistical significance between 3 groups (p=0.09). Conclusion : We conclude that renal malformation occurs in 9.2% in this study, therefore Korean girls with Turner syndrome have lower rates of renal malformation.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.20 no.8
• /
• pp.717-726
• /
• 2010

For the application into a 1 kWh flywheel energy storage system(FESS), this paper presents the design scheme of radial and axial hybrid magnetic bearings which use bias fluxes generated by permanent magnets. In particular, the axial hybrid magnetic bearing is newly proposed in this paper, in which a permanent magnet is arranged in axial direction so that it can support the rotor weight as well as provide a bias flux for axial magnetic bearing. Such hybrid magnetic bearings consume very low power, compared with conventional electromagnetic bearings. In this paper, to stably support a 140 kg flywheel rotor without contact, design process is explained in detail, and magnetic circuit analysis and three-dimensional finite element analysis are carried out to determine the design parameters and predict the performance of the magnetic bearings.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.63 no.2
• /
• pp.237-244
• /
• 2014

In this paper, we presented a study on the design of permanent magnet rotor for exterior rotor type brushless direct current(BLDC) motor. To reduce the cogging torque and torque ripple, the specific shape and magnetization pattern of permanent magnets in BLDC motors are suggested. Firstly, four permanent magnet models with different shapes and magnetization arrays are presented. The results from the finite element method(FEM), the most effective model for reducing cogging torque and torque ripple was presented. In addition, to confirm the steady state performance, the torque-speed characteristic analysis has been performed with variable speed and load. Finally, the best permanent magnet model for reducing cogging torque and torque ripple with appropriate torque-speed performance was selected through the comparison according to the device volume.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.27 no.8
• /
• pp.36-41
• /
• 2013

This paper is development of single-phase brushless DC motor with outer rotor for ventilation fan. Cogging torque causes the noise vibration to greatest impact on ventilation fan. Asymmetric notches are applied to tapered-teeth for cogging torque reduction of single-phase brushless DC motor. Initial model is notchless and proposed model is applied 2 asymmetric notches. The proposed method is proved motor characteristic through finite element analysis(FEA). Also, experimental results verify that the proposed model considerably reduces cogging torque and have the good sound quality in ventilation system.