• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.2
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• pp.356-362
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• 2009

The ELectromagnetic Core Imperfection Detector (EL-CID) test was performed on a small generator in the laboratory and a gas turbine generator in the field to assess the fault condition of generator stator core. Artificial defects with six different sizes were introduced in the small generator. The scan results on six defects show a very large increase in the magnitude of fault current compared to that obtained with a healthy core. After the stator core heats up, a thermal imaging camera was used to detect hot spot on the inner surface of the core for comparison. Several faults were found during inspection of the gas turbine generator with the EL-CID. It has been shown that the existence of a fault can be determined by monitoring the magnitude of fault current.

• Journal of Electrical Engineering and Technology
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• v.9 no.4
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• pp.1349-1354
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• 2014

This paper presents a compact and portable high-voltage generator based on magnetic-core Tesla transformer for driving an UWB high power electromagnetic source. In order to optimize the performance of the high-voltage generator, a novel open-loop cylindrical magnetic-core adopting the quad-division lamination structure is proposed and manufactured. The designed high-voltage generator using the proposed magnetic core has a battery-powered operation and compact size of $280mm{\times}150mm$ in length and diameter, respectively. The high-voltage generator can produce a voltage pulse waveform with peak amplitude of 450 kV, a rise time of 1.5 ns, and pulse duration of 2.5 ns at the 800 V input voltage.

• Journal of KSNVE
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• v.9 no.4
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• pp.747-753
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• 1999

This paper presents results of vibration analysis of a generator-stator core for 500 MW fossil power plant. A finite element analysis using a commercial S/W is performed to estimate alternating electromagnetic forces, mainly of 120 Hz in 60 Hz machines, acting on the core, and then to calculate forced response of the core. Results are compared with design requirements.

• 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.

• 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
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• v.61 no.2
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• pp.223-230
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• 2012

This paper deals with an design of axial flux electric machine which is a key element for a compact size in a portable and manual generator system. It is expected that the generator system with an axial flux electric machine is more light and has higher efficiency than other types of generator systems. And it is used the soft magnetic composite core instead of silicon steel core in the axial flux electric machine for more compact size. The weight and efficiency of the generator system are the main keys to select the value of design variables. In this paper, the overall design process to meet the design goals, and the design results are presented with experiment results.

• Journal of Magnetics
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• v.16 no.4
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• pp.374-378
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• 2011

Axial Field Permanent Magnet (AFPM) generators are widely applied for the small wind turbine because of the higher power density per unit weight than that of the conventional radial field generator. It is caused by the disc shaped rotor and the stator structures. The generally used AFPM generator, AFER-NS generator, is composed of the two side's external rotors and non-slotted stator without stator core. However, the output voltage and the output power are limited by the large reluctance by the long air-gap flux paths. In this paper, the design study of AFIR-S generator having double side's slotted stator core is accomplished to improve the output generation characteristics. The electromagnetic design analysis and the design improvement of the suggested AFIR-S generator are studied. Firstly, the electromagnetic design analysis was done to increase the power density. Secondly, the design optimizations of the rotor pole-arc ratio of permanent magnet are accomplished to increase the output power and to reduce the cogging torque. Finally, the output performances of AFER-NS and AFIR-S generator are compared with each other. For this study, 3D FEA is applied for the design analysis because of three dimensional electromagnetic structures.

• 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.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.7
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• pp.75-80
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• 2014

The small wind turbines 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 permanent magnet synchronous generator(PMSG) skewed for magnet of rotor, the main advantage to be explored with the use of a split core design is the reduction in manufacturing costs and its simplicity in manufacture, compared to the manufacturing costs of a core skew PM machine. This thesis is aiming mainly analyzing the characteristics of the prototype to verify through Finite Element Method(FEM) and tests.