• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.4
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• pp.379-382
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• 2014

In this paper, the cogging torques were calculated for 1kw double-sided axial flux permanent magnet (AFPM) generator with different stator core pole arrangements. The generator is composed of 18 stator pole and 24 rotating field magnets on each side. The cogging torques of the generator with three types of arrangements of stator poles were calculated using 3D finite element method and the optimum core shape was determined to minimize the cogging torque.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.5
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• pp.222-230
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• 2005

This paper deals with the reduction of cogging torque of a outer-rotor type BLDC motor mainly used for washing machines. The motor comprises permanent magnet outer-rotor and stator with coils and core. This structure inherently produces vibration and cogging torque because of uneven reluctance according to rotation of the rotor. Up to now, adopted a type of 24 magnet pole and 36 slot-stator. This generates high main torque but accompanies comparatively large cogging torque. This paper proposes a 32-pole 36-slot type motor which reduces cogging torque remarkably. The influence of cogging torque is varied according to pole-slot combinations. The characteristic of the motor was obtained by a two-dimensional finite element method coupled with a drive circuit. The performance of the proposed model is superior to that of the existing model because of the reduction of torque ripple and the improvement of back ernf wave form.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.2
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• pp.134-140
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• 2013

This paper proposes a new design of rotor shape of Interior Permanent Magnet Synchronous Motor (IPMSM) used for agricultural electric vehicle (AEV). The distribution of the residual magnetic flux density at the air gap is modified by rotor surface shape and V-type magnet angle. As a result, cogging torque and physical characteristic have been improved, and back electromotive force (back-EMF) of the suggested model has been improved to be closest to sine wave form compared to initial model. The validity of the proposed rotor shape optimization is confirmed by the manufactured IPM rotor core and measured the performance of the cogging torque.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.641-643
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• 2002

Synchronous generator needs slip-ring and brush for supplying current to rotor with external source. but slip-ring and brush have some problems to supply DC power to field winding with friction and high power loss due to brush voltage drop at high field current. Thus synchronous generator have been designed to brushless machine. Brushless synchronous machines of using permanent halbach array can composed without back core and coreloss. In this paper, analyse on the characteristics of external rotor type permenant magnet brushless with halbach array.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.12
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• pp.2230-2235
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• 2011

The purpose of this paper is to provide the unbalanced magnetic force and vibration mode comparison between two large interior permanent magnet machines(IPM) with different pole-slot combination considering stator and rotor eccentricity. Due to the punching tolerance, the mixed eccentricity of air-gap is inevitable. It will generate the asymmetric magnetic flux density in air-gap, which makes the unbalanced magnetic pull and vibration. The study is focused on the unbalanced magnetic force and their harmonic components according to eccentricity conditions such as static, dynamic and mixed. When the high vibration is produced especially resonance, the obtained results provide clues what eccentricity condition occurs in the machine.

• Journal of Electrical Engineering and Technology
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• v.4 no.3
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• pp.377-381
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• 2009

In the development of an interior permanent magnet synchronous machine (IPMSM) for high-speed operation, the problem of mechanical stress of the rotor by centrifugal force becomes more essential as the speed and size of the machines increase. In this paper, the optimal design process combined with mechanical stress analysis was presented. In the analysis of mechanical stress, the node and element data obtained by the electromagnetic field analysis program are also used in the stress analysis. Therefore, the different pre-processing for the stress analysis program is no longer required. Therefore, the computing time of the new method is very short compared with the conventional approach, and when repeated analyzes of various models are required, this method is very useful. The validity of our methods was verified by comparing simulation results with conventional and experimental data.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.71-73
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• 1996

Klaus Halbach has suggested the novel permanent magnet array using advanced analytical approaches in 1979. We utilize this Halbach array to compose the field system of high speed motor-generator. The ferro-magnetic materials of the electric machines cause the fatal energy loses in high frequency. But Halbach array enables to make the various field distribution without ferro-magnetic materials. Therefore, the energy loses can be reduced. This paper presents the magnetic characterics of Halbach array and the application to the motor-generator.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1111-1112
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• 2011

This paper investigated application of fractional-slot concentrated-winding axial flux permanent magnet machines for wind turbines. Design criteria of cogging torque and voltage regulation was firstly proposed for this kind of application. Fractional winding has small cogging torque which is highlight for wind turbines, but slot leakage inductance would increase voltage regulation, which is an important performance index of generators. By varying slot opening, cogging torque and slot leakage inductance could be adjusted. In this paper, cogging torque and inductances were calculated by both analytical and finite element methods. Voltage regulation was studied by two-axis model under unity-power-factor load and verified by transient finite element analysis.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.981-982
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• 2011

This paper discusses design aspects of slotless permanent magnet generator for high performance and low speed applications. The airgap flux density in was obtained from finite element analysis and the design of a PM generator. The relatively large diameter stator laminations of such machines tend, therefore, to have a very thin back of core and narrow teeth, which make them expensive and difficult to manufacture. this thesis proposes an alternative PM generator topology featuring a slotless stator whose laminations are manufactured from a split core. The test results with a resistive load confirm the satisfactory operation of generator.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.708_709
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• 2009

The small wind turbines under a few kW grades has the merits of setting up with low costs by individuals, and get the energy saving effects that, it has the secured, separate markets from the big range systems, and the developing of it is continuously proceeding. The objective of this paper is to provide the design characteristics analysis of a dual-rotor, ironless, Radial Flux Permanent Magnet(RFPM) machines for small wind turbine. This thesis is aiming mainly analyzing the characteristics of the output power of the Prototype to verify through the theoretical study and tests. The results reveal an indication of the machine best suited with respect to performance criterion for a particular design requirement.