• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.4
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• pp.299-305
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• 2005

The work described in this paper is to investigate the additional iron losses and consequent temperatures in core ends of a turbo-generator wound with high voltage cables. Electromagnetic calculations are made with 3D FE models, which include the lamination material with anisotropic properties both in magnetic permeability and electric conductivity. The models also include the geometry of the stator teeth and eventually the axial steps designated to reduce the core end losses. The 3D model of the rotor consists of field windings with straight in-slot parts and end windings. The thermal models are simplified into two dimensions and include the heat sources dumped from the 3D electromagnetic solutions. The influences of power factor on additional iron losses are studied for this cable wound machine and conventional machines. The calculation results show that the additional iron losses can be reduced to about $15\%$ by introducing some small steps around the airgap corner of core ends.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.55-57
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• 2009

This paper deals with an improved core loss calculation under the load conditions, namely, no-load, AC-load and DC-load of multi-pole PM generator from curve fitting method using modified Steinmetz equation considered anomalous loss. For an accurate calculation, magnetic field analyses in stator core considering the time harmonics are performed. And using the nonlinear finite element analysis (FEA), we applied separated rotating and alternating magnetic field to core loss calculation. In order to verify the core loss results by proposed method, the experimental system for no-load core loss measurement has been implemented with DC motor, power analyzer and manufactured PM generator. And, the analysis results with rotational speed agree extremely well with those obtained by measurement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.1044-1048
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• 2002

The experimental modal testing has been carried out for the stator of a generator to confirm the vibrational mode shapes and the corresponding natural frequencies. The model of the stator for the vibration analysis was developed and a series of vibration analyses was carried out. And the properties of the solid element were updated to reduce the differences of the natural frequencies between the measured and the analysed. In the vibration anlyses, the axial, radial and circumferential properties of the solid element were separately varied to take into account the orthotropic effect of the laminated structure and to match the primary modes of the stator core which were extracted from the modal testing. After several attempts to match the measured natural frequencies and model shapes, the properties of the stator model were determined. Comparison of the vibration analyses results based on the determined properties showed fairly good coincidence with the measured data.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.800-801
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• 2011

This paper proposes a grid-connected to rotor type doubly fed induction generator (DFIG) in which the rotor winding is connected to the grid instead of the stator winding. The stator size and weight of the proposed grid-connected to rotor type DFIG can be reduced because the proposed type can use rotor core more efficiently compared to the stator type DFIG. In order to verify the size and weight reduction of the proposed type, the loading distribution method (LDM) is utilized. As a design result, the stator outer diameter and weight of the proposed type were decreased. The equivalent circuit analysis and finite element method also performed to verify the design results and to analyze characteristics of the novel DFIG.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.6
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• pp.42-48
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• 2011

Generally, the structure without the stator core Axial Field Permanent Magnet (AFPM) generator was simple and there was nearly no cogging toque. And because it had the wide driving rate area, it had been being mainly used in the small wind power generation system. However, AFPM generator with non-slotted stator can't generate high voltage at low wind speed due to long air-gap. It is the reason of output efficiency drop. Therefore, in this paper, the AFPM synchronous generator with internal rotor and dual slotted stators for the small wind turbine is studied, and deal with a cogging torque minimization through the determination of optimum pole-arc ratio.

• Journal of Magnetics
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• v.16 no.2
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• pp.124-128
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• 2011

This study estimated experimentally the loss distribution caused by magnetic friction in magnetic parts of a superconductor flywheel energy storage system (SFES) to obtain information for the design of high efficiency SFES. Through the spin down experiment using the manufactured vertical shaft type SFES with a journal type superconductor magnetic bearing (SMB), the coefficients of friction by the SMB, the stator core of permanent magnet synchronous motor/generator (PMSM/G), and the leakage flux of the metal parts were calculated. The coefficients of friction by the stator core of PMSM/G in case of using Si-steel and an amorphous core were calculated. The energy loss by magnetic friction in the stator core of PMSM/G was much larger than that in the other parts. The level of friction loss could be reduced dramatically using an amorphous core. Energy loss by the leakage magnetic field was small. On the other hand, the energy loss could be increased under other conditions according to the type of metal nearby the leakage magnetic fields. In manufactured SFES, the rotational loss by the amorphous core was approximately 2 times the loss of the superconductor and leakage. Moreover, the rotational loss by the Si-steel core is approximately 3~3.5 times the loss of superconductor and leakage.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.115-117
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• 2007

Core loss form a larger proportion of the total losses. This paper deals with the analysis on the core loss in PM generator considering the operating speed for wind power application. Using the data information from a manufacturer and nonlinear curve fitting, this paper investigates the magnetic behavior and its core losses in the stator core using the electrical steels.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.9
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• pp.53-61
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• 2013

This paper propose a improved operating characteristics of the 5-phase 5kW within developed the surface permanent mount synchronous generator (SPMSG) in order to make a study of a polyphase ac motors keeping hold of more advantages. The developed manufacturing motor was necessary to do improvement of voltage regulation, efficiency, operating characteristics, and so on at the rated load. There are remake a redesigned and distributed stator winding connection without changing the frames of stator and rotor core in previous established generator by a repeat tests. There are shown a amplitude and waveform of the generated electromotive force, FFT analysis of harmonics within output voltages, and reviewing a experiment results in load of resistive and 5-phase induction motor by variable generator output frequency.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.401.1-401
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• 2002

The state core of a motor/generator was modeled using dynamic model updating technique based on the modal testing work. In order to take into account the orthotropic effect of laminated structure the axial, radial and circumferential properties of the solid element were separately varied to match the primary modes of the stator core which were extracted from the modal testing. Comparison of the results after model tuning showed fairly good coincidence with measured data.

• Journal of Power Electronics
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• v.17 no.4
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• pp.1027-1036
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• 2017

The brushless doubly-fed induction generator (BDFIG) is a new type of dual stator winding induction generator. In such a generator, both the power winding (PW) and the control winding (CW) are housed in the stator. This paper presents the performance characteristics of a stand-alone BDFIG operation system. A new T-type steady-state model of a BDFIG is proposed. This model is more suitable for the performance analysis of stand-alone BDFIGs than the conventional Π-type steady-state model and the simplified inner core steady-state model. The characteristics of the power flow and CW current are analyzed by detailed mathematical derivations on the basis of the proposed T-type steady-state model. The analysis results are verified by experiments, which are carried out on a prototype BDFIG. The results of the performance analysis contribute to simplifying the control circuit, improving the control performance, and selecting an appropriate BDFIG for actual industrial applications.