• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.135-137
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• 2001

In slotless synchronous motor for precise position and speed control, eccentricity of rotor mass cause torque ripple, speed ripple and harmonics of back emf. This paper deals with magnetic field and characteristic analysis for ring type slotless synchronous motor by using analytical method. And then, speed and back emf harmonics are analysed.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.4
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• pp.273-279
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• 2016

In this paper, a high-performance control of the induction motor for electric car was implemented to escape dependence of the rare earth magnet. Proposed high-efficiency control algorithm is a Direct Rotor Field-Oriented Control method that is insensitive to the fluctuation of motor parameters. In the DRFOC method, we need to compensate fluctuation of stator transient inductance and magnetizing inductance caused by the magnetic saturation of induction motor in high-speed area. This paper proposes Back-EMF Observer based on stator current estimator of Luenberger style. Motor control system applied the Voltage Feedback Flux Weakening Control method for high-speed operation. The proposed algorithm was verified through tests by the power train of Extended Range Electric Vehicle consists of induction motor and differential gear.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.9 no.6
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• pp.711-718
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• 2019

Spectrum analyzer and electromagnetic field meter were used to investigate the EM generation behaviour in different types of home electrical appliances. During microwave oven operation, the EM power measured at a point 30cm apart was measured in the range of 8~11mW/㎡, the strength of the low frequency magnetic field was 60~80mG and the electric field strength was measured at 150~160V/m. For smart phone wireless charging pad, it was measured at an electromagnetic power of 0.4mW/㎡, an electric field of 160 V/m and a magnetic field of 1mG at a point 10cm away. For microwave oven and wireless charging pad, if used within 10cm, the size of the electric field has been measured at a large value that exceeds the human body protection standard and may be hazardous to humans. On the other hand, home appliances such as TVs, hairdryers and refrigerators all showed very low levels of electromagnetic waves, electric fields and magnetic fields, with no harmful effects seen. For electromagnetic shielding, the metal Cu fabric and metal foil had a high level of EM shielding, while polymer films had a low EM shielding characteristic.

• Proceedings of the KIEE Conference
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• 2002.04a
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• pp.31-33
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• 2002

This paper is presents dynamic analysis of slotless PM linear synchronous motor using 3-D analytical method and improvement of controllability using PI control system. In oredr to calculate dynamic characteristic, back-EMF waveform and inductance are caculated by PM's magnetic field and winding's magnetic filed respectively. PMLSM simulated by PI control system.

• Journal of Biomedical Engineering Research
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• v.16 no.2
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• pp.191-200
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• 1995

Although air, water, and noise pollutions have been widely recognized, electromagnetic forces (EMF) hazard has been rarely recognized as a pollution and very little studies has been done in this country. Thus, in this study electromagnetic forces radiated by various home appliances, office machines, and communication equipments were measured and so were several places radiating strong EMF such as subway stations and electric substations. Among the home appliances microwave oven radiates lots of magnetic field and microwaves, and electric mattress does strong magnetic field. In video game room strong magnetic and considerable electric fields were measured. It was observed strong magnetic field inside of electric powered train and very strong magnetic and electric fields on some platforms. Hand-phone and car-phone radiate very hazardous level of microwaves to brain and that they rapidly come into wide use. In this study data base for various electric machines and places radiating strong EMFs were constructed and could be used for future epidemiological studies.

• Journal of Electrical Engineering and Technology
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• v.1 no.2
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• pp.185-191
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• 2006

In this paper, a novel stator hybrid excited doubly salient permanent magnet (SHEDS-PM) brushless machine with a special magnetic bridge is proposed for the first time. The originality of this machine is purposely to add a magnetic bridge in shunt with each PM pole, which not only maintains the stator lamination in its entireness, but also amplifies the effect of DC field flux on PM flux. An equivalent magnetic circuit is presented to clarify the novelty. Based on the 2-D finite element analysis, the static characteristics of the SHEDS-PM machine, namely phase flux linkage, back-EMF, cogging torque, winding inductance and static torque are deduced. The corresponding results on a prototype machine illustrate that the proposed machine is promising for application to electric vehicles.

• Journal of electromagnetic engineering and science
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• v.11 no.4
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• pp.298-303
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• 2011

A capsular endoscope (CE) for inspection of the large intestine requires a motor for backward navigation against the autonomous travel in the intestine. This study proposes an HF power system for generating a magnetic field and for delivering wireless power to the internal or implanted medical devices. The magnetic field is generated by a wound coil (L) around a wooden frame, and the current is driven to the coil through a resonating capacitor (C). The characteristics of the resonance frequency shifting of the L-C series circuit are analyzed. A stable magnetic field intensity in the field coil is maintained by a specially designed frequency tracking system that automatically follows the L-C resonance frequency. Testing confirmed that the oscillation system tracks well the parameter changes of the electric components caused by the operating conditions or environmental variations.

• Journal of the Korean Society for Railway
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• v.17 no.4
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• pp.228-232
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• 2014

The magnetic field generated by the feeding line of a wireless power transfer system induces voltage on the rail of a railway system. The induced voltage of the rail can have a bad influence on the track circuit and on safety. This paper simulated three feeding lines to study the relation between the feeding lines and the induced voltage of the rail; it also proposed magnetic field distribution of the feeding line to reduce the induced voltage.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.22-24
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• 1996

For two decades and more, a lot of research work on the biological effects of EMF(Electromagnetic Fields) on Human hearth have been reported. Power-frequency magnetic fields are a natural consequence of the flow of electricity. This paper deals with the modeling of electric utility facilities taking into account the line geometries. The magnetic fields profiles obtained from the computer simulation arc compared to those from measurements.

• Journal of electromagnetic engineering and science
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• v.9 no.4
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• pp.175-181
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• 2009

The measurements were performed to verify experimentally that the voltage arising on a telecommunication line by a power line is due to the induction phenomena because there has been an opinion that the arising voltage on a telecommunication line is not by induction, but by other causality. The voltage appeared on the telecommunication line by way of an electric field or magnetic field generated by the source apparatus that had been artificially made to provide intentional constant high-voltage or current in ELF, that is, 60 Hz as an emulated commercial power.