• 전기학회논문지
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• 제62권11호
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• pp.1528-1534
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• 2013

This paper proposes the optimal design of stator shape for cogging torque reduction of single-phase brushless DC (BLDC) motor with asymmetric notch. This method applied size and position of asymmetric notches to tapered teeth of stator for single-phase BLDC motor. Which affects the variation of the residual flux density of the permanent magnet. The process of optimal design included the extraction of the sampling point by using Latin Hypercube Sampling(LHS), and involved the creation of an approximation model by using kriging method. Also, the optimum point of the design variables were discovered by using the Genetic Algorithm(GA). Finite element analysis was used to calculate the characteristics analysis and cogging torque. As a result of finite element analysis, cogging torque were reduced approximately 39.2% lower than initial model. Also experimental result were approximately 38.5% lower than initial model. The period and magnitude of the cogging torque were similar to the results of FEA.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.83-86
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• 1988

In all sorts of primary factor which produce torque ripple of d.c brushless motor cogging torque which is generated from relation between permanent magnet rotor and salient pole cannot controled by external control system. So in this paper cogging torque is analysed by simple method in which slot fuctuion is introduced. And for reducing counterplan of cogging torque d.c brushless motor which plot auxiliary slot by inequality interval is proposed. Thus the quantitative torque characteristics of new motor which designed by this method is analysed by F.E.M and validity of this new design is proved.

• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.188-194
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• 2015

This paper proposes a generalized regression neural network (GRNN) based algorithm for data interpolation and design optimization of brushless dc (BLDC) motor. The procedure makes use of magnet length, stator slot opening and air gap length as design variables. Cogging torque and average torque are treated as performance indices. The optimal design necessitates mitigating the cogging torque and maximizing the average torque by varying design variables. The data set for interpolation and ensuing design optimisation using GRNN is obtained by modeling a standard BLDC motor using finite element analysis (FEA) tool MagNet 7.1.1. The performance indices of the standard motor obtained using FEA are validated with an experimental model and an analytical method. The optimal design is authenticated using particle swarm optimization (PSO) algorithm and the performance indices of the optimal design obtained using GRNN is validated using FEA. The results indicate the suitability of GRNN as an interpolation and design optimization tool for a BLDC motor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.815-816
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• 2006

This paper proposes a novel design method for flux barrier which built in q-axis in rotor of IPM type BLDC motor. It aims to reduce the motor vibration with reduced cogging torque and lessened torque ripple by the sinusoidal waveform distribution of flux generated in the permanent magnet, which results from designed flux barriers. Design of flux barrier optimized using the Taguchi methods that considered multiple quality characteristics, such as cogging torque, average torque and efficiency are considered. The result of proposed method is compared and verified with 2D finite element method (FEM).

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권2호
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• pp.49-54
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• 2002

Most single-Phase brushless DC (BLDC) motors have unequal air gap to eliminate the dead-point where the developed torque value is zero. However this partial increase of the air gap deteriorates the motor characteristics in cogging torque. Thus in this paper a new topology of unequal air gap is proposed to solve this problem. The topology is to use some pairs of equal or unequal air gaps. As a result, it is proved by the finite element analysis and experimental results that the single-Phase BLDC motor with the proposed air gap topology is very effective in reducing the cogging torque.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1180-1182
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• 2005

In this paper, the design and field analysis of the novel axial flux type permanent magnet(AFPM) motor with double stator and single rotor are investigated. The various design schemes of AFPM based on 3D finite element method are proposed. The effects of slot shapes, various magnetization of PM, and skewing on the cogging torque and average torque have been investigated in detail. From the results, we can improve the cogging torque and average torque characteristics.

• 전기학회논문지
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• 제65권2호
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• pp.279-285
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• 2016

In this paper, a cogging torque of IPM(Interior Permanent Magnet)-type BLDC motor is analyzed by FE program and the optimized notch on the rotor surface is designed to minimize the torque ripple. A differential evolution strategy algorithm and a response surface method are employed to optimize the rotor notch. In order to verify the proposed algorithm, an IPM BLDC motor is used, which is 50 kW, 8 poles, 48 slots and 1200 rpm at the rated speed. Its characteristics of the motor is calculated by FE program and 4 design variables are set on the rotor notch. The initial shape of the notch is like a non-symmetric half-elliptic and it is optimized by the developed algorithm. The cogging torque of the final model is reduced to $1.5[N{\cdot}m]$ from $5.2[N{\cdot}m]$ of the initial, which is about 71 % reduction. Consequently, the proposed algorithm for the cogging torque reduction of IPM-type BLDC motor using the rotor notch design seems to be very useful to a mechanical design for reducing noise and vibration.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.202-205
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• 2008

This paper presents an optimization of permanent magnet (PM) in a brushless dc (BLDC) motor using the response surface methodology (RSM). Size and angle of the PM are optimized to minimize the cogging torque, while reducing the magnitude of harmonic at a dominant frequency and maintaining the operating torque. A fitted RS model is constructed by verifying the high reliability of the total variation and the variation of estimated error. The optimized design is validated by carrying out the reanalysis and comparing to the initial model using the nonlinear transient finite element analysis.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(2)
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• pp.824-827
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• 2003

Recently, Development of Rare Earth Permanent magnet with the high remanence, high coercivity allow the design of brushless motors with very high efficiency over a wide speed range. Cogging torque is produced in a permanent magnet by magnetic attraction between the rotor mounted permanent magnet and the stator teeth. It is an undesired effect that contributes to the machines output ripple, vibration, and noise. This cogging torque can be reduced by variation of magnet arc length, airgap length, magnet thickness, shifting the magnetic pole and varying the radial shoe depth and etc. In this paper, Some airgap length and magnet arc that reduce cogging torque are found by FEM(Finite element method). The SPM type of high-capacity BLDC motor is optimized as a sample model.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 A
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• pp.159-161
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• 1997

This paper presents a method of reducing cogging torque and improving average torque by changing the dead zone angle of trapezoidal magnetization distribution of rotor magnet in ring type. Because brushless d.c. motor has 3D shape of overhang, 3D analysis should be used for computation of its magnet field. In this paper, Three Dimensional Equivalent Magnetic Circuit Network method (3DEMCN) which can calculate an accurate 3D magnetic field has been introduced. The method has an advantage that nonlinear magnetic phenomena can be considered and the cogging torque analyses requesting the rotation of the rotor can be performed by the variation of magnetization distribution without remesh.