• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.3
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• pp.272-276
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• 2005

This paper deals with the method to calculate the rotor eddy current losses of permanent magnet high-speed machines considering the effects of time/space flux harmonics. The flux harmonics caused by the slot geometry in the stator is calculated from the time variation of the magnetic field distribution obtained by the magneto-static finite element analysis and double Fast Fourier Transform. And, using the analytical approach considering the multiple flux harmonics and the Poynting vector, the rotor losses is evaluated in each rotor composite. Using this method is simple and workable for any kind of stator slot shape for rotor loss analysis.

• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.63-67
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• 1990

An axial flux magnet for a magnetic levitation system is designed and analysed by finite element simulations. The results are compared with those of experiment in order to verify the analysing method. Lift force, air gap flux density and temperature characteristics of the magnet showed fairly good agreement with each other.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.286-292
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• 2008

Transverse flux machine (TFM) has been developed to drive a machine of large input power at low-speed. However, it has complicated structure and large torque ripple due to its inherent structure In this paper the characteristics of torque of a rotatory two-phase TFM are analyzed by using the 3-dimensional finite to element method and optimal design. This research shows that one of the effective design variables is the skew angle of permanent magnet. The skew angles of permanent magnet are optimized by using a Progressive Quadratic Response Surface Method (PQRSM). It also shows that the proposed optimal skew magnet not only increases average torque but also decreases torque ripple of a rotatory two-phase TFM.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.645-648
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• 1992

In a capacitor-discharge impulse magnetizer, one of the magnetic application system, a magnet is magnetized by the discharging current of capacitors. The conventional design of the magnetizer has been based on many year's experience. The behaviour of flux in the magnetizer should be calculated in order to produce the desired magnets. The analysis of the flux distribution is quite difficult. This is because both the magnetizing current and the applied voltage to the magnetizer are unknown. This paper describes the development of computer model for a capacitor-discharge impulse magnetizer using SPICE. Also, the detailed distribution of the flux density in a magnet magnetized by the impulse magnetizer be analyed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.10
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• pp.1003-1011
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• 2009

Transverse flux machine(TFM) has been developed to drive a machine of large input power at low-speed. However, it has complicated structure and large torque ripple due to its inherent structure. In this paper the characteristics of torque of a rotatory two-phase TFM are analyzed by using the 3-dimensional finite element method and optimal design. This research shows that one of the effective design variables is the skew angle of permanent magnet. The skew angles of permanent magnet are optimized by using a genetic algorithm. It also shows that the proposed optimal skew magnet not only increases average torque but also decreases torque ripple of a rotatory two-phase TFM.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.5
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• pp.942-948
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• 2011

This paper deals with characteristic analysis of axial flux permanent magnet (AFPM) machines with axially magnetized PM rotor using quasi-3-D analysis modeling. On the basis of magnetic vector potential and a two-dimensional (2-D) polar-coordinate system, the magnetic field solutions due to various PM rotors are obtained. In particular, 3-D problem, that is, the reduction of magnetic fields near outer and inner radius of the PM is solved by introducing a special function for radial position. And then, the analytical solutions for back-emf and torque are also derived from magnetic field solutions. The predictions are shown in good agreement with those obtained from 3-D finite element analyses (FEA). Finally, it can be judged that analytical solutions for electromagnetic quantities presented in this paper are very useful for the AFPM machines in terms of following items : initial design, sensitivity analysis with design parameters, and estimation of control parameters.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.80-82
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• 2007

This paper presents the overhang effects of a novel axial flux permanent magnet (AFPM) machine, which consist of the segmented stator and fractioned slot windings, with one rotor and double stator. In addition, the overhang effect of permanent magnet of the motor has been analyzed quantitatively. The overhang is used to enhance the force density in permanent magnet machine. According to the variation of overhang length, the flux density distribution and torque are quantitatively compared. For these analysis, three dimensional finite element method (3D FEM) has been used in this paper. From the results, the proper overhang length of PM is selected to improve the performance of the AFPM machine.

• Proceedings of the KIEE Conference
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• 2007.11c
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• pp.149-154
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• 2007

The classical literature on SR motor design tends to focus on inner-rotor type motor rather than outer-rotor type motor, and dose not provide a complete procedure for configuration of outer-rotor type SR motor calculations that are also needed in every SR motors design. It is interested in the design of SR motors to shortening the magnet flux path in the iron core for reducing the iron loss. The 5 phases outer-rotor type SR Motor with short magnet flux path is introduced in this paper. For this the rotor of prototype is designed in U-form with 8 rotor poles that are in 4 U-forms from one another separate constructed.

• Journal of Magnetics
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• v.17 no.2
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• pp.100-108
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• 2012

Flux concentrated permanent magnet transverse flux machines, FCPM-TFMs, with segmented stators require multi-turn concentric saddle coils to replace the ring coils, which are normally utilized in conventional layeredphase TFM constructions. In this paper, we investigate the influence of the shape of saddle phase windings and their parameter variations on the output torque productivity. Non-meshed coils evaluated via a finite element method (FEM) to examine the effect of the coil's location within one phase on machine performance. By using meshed coils, the analysis can be extended to inspect the distributions of magnetic field strength as well as current density in the coils. Throughout the study, the influence of design parameters on the output torque for two stator structures, i.e., a laminated and soft magnetic composite (SMC), are evaluated.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.9
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• pp.437-442
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• 2006

Cogging torque, the primary ripple component in the torque generated by permanent magnet (PM) motors, is due to the slotting on the stator or rotor. This article shows the reduction of cogging torque in a novel axial flux permanent magnet (AFPM) motor through the various design schemes. 3D finite element method is used for the exact magnetic field analysis. The effects of slot shapes and skewing of slot on the cogging torque and the average torque have been investigated in detail.