• 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.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.4
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• pp.716-723
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• 2007

This paper suggests of a 3-phase 3-wire unified active power filter. The system is composed of a series active power filter and a parallel active power filter. The proposed series active power filter compensating unbalance source voltage and current harmonics of the parallel active power filter improves power factor. The proposed algorithm which improves for power factor and harmonic reduction are calculated by the performance function, and which compensates for the unbalanced source voltage is calculated based on the symmetrical component analysis. We composed a combined system of the series active power filter and parallel active power filter to confirm a validity of the proposed control methods. The effectiveness of the proposed algorithm is confirmed by the experiments.

• Proceedings of the KIEE Conference
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• 2007.11c
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• pp.125-127
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• 2007

Presented increase and so on of switch stress and switching dissipation and EMI that is happened in general PWM converter and in this study to solve problem the resonance energy return to life rate and new active snubber PWM converter because do maximization. Active snubber PWM converter that try adds auxiliary switch and resonance capacitor, diode to existing converter under all switching conditions turn on/off Minimised switching dissipation that occur. Reduced harmonic components absorbing station recovery electric current that happen to snubber diode inserting diode and resistance. And decreased peak current that is happened in auxiliary switch arranging resonance capacitor and inductor properly, Certified effect that efficiency rises about 2.5[%] more than existent PWM converter in rated load through an experiment.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.5
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• pp.67-73
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• 1997

인버터의 출력파형에 포함되는 고조파를 저감하기 위하여 소프트웨어에 의하여 W형태와 M형태의 펄스 폭변조 신호로 구동되는 3상 5레벨 PWM인버터를 구현하였고, 인버터의 출력전압의 종합 고조파 왜율은 비교 분석하였다. 제안한 M형 펄스 폭 변조 제어에 의하면 PWM 인버터의 종합 고조파가 크게 낮출 수 있어 인버터 응용 시스템의 성능을 향상시킬 수 있다. W형 및 M형의 펄스 폭 변조제어 3상 5레벨 PWM 인버터를 구현하여 인버터 출력전압의 종합 고조파 왜율을 5〔%〕이하로 유지됨을 입증하였다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.3
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• pp.81-87
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• 2000

The increasing use of non-linear loads such as power electronics draw highly distorted currents from the utility system. High harmonics currents and voltages will cause equipment damage and disturb the plant operation. The common solution to harmonics problem is to use harmonics filters. In this paper simulation results used the EDSA harmonics analysis program verifying the effects of the single-tuned filter for harmonic elimination are presented.

• Computers and Concrete
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• v.20 no.3
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• pp.361-368
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• 2017

Seismic response of the concrete column covered by nanofiber reinforced polymer (NFRP) layer is investigated. The concrete column is studied in this paper. The column is modeled using sinusoidal shear deformation beam theory (SSDT). Mori-Tanaka model is used for obtaining the effective material properties of the NFRP layer considering agglomeration effects. Using the nonlinear strain-displacement relations, stress-strain relations and Hamilton's principle, the motion equations are derived. Harmonic differential quadrature method (HDQM) along with Newmark method is utilized to obtain the dynamic response of the structure. The effects of different parameters such as NFRP layer, geometrical parameters of column, volume fraction and agglomeration of nanofibers and boundary conditions on the dynamic response of the structure are shown. The results indicated that applied NFRP layer decreases the maximum dynamic displacement of the structure. In addition, using nanofibersas reinforcement leads a reduction in the maximum dynamic displacement of the structure.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.1
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• pp.27-33
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• 2005

The development of modern high-energy magnet materials has allowed the replacement of field coils in many different types of electromagnetic energy conversion machines. As well, the linear synchronous motor has recently been proposed for linear motion with high efficiency and thrust. Thus, this paper presents an analytical solution for the high thrust and cost reduction of the Iron-Cored Permanent Magnet Linear Synchronous Motor (PMLSM) considering magnetization arrays and geometry. Hence, the superior utilization points in each of the magnetization arrays are provided by the height ratio of the magnet/air-gap and magnet/winding coil, etc. In formulation, the space harmonic method in analytical solutions and the generalized 2-D tensor finite element analysis can be used to evaluate force components in magneto static devices including the magnetostrictive phenomenon.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1061-1063
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• 2001

This paper proposes a new power conditioning system for the SMES composed of a thyristor PWM converter with a resonant commutation circuit. The operation of the proposed system and the dynamic interaction between SMES and the power system is analyzed by a theoretical approach with equivalent circuits and verified by computer simulations with EMTP, considering a typical 154kV power system. The proposed system can provide a solution for the power factor regulation and harmonic level reduction in the ac terminal with low-cost system configuration.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.252-254
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• 2000

For many years, electric utility has used sustained interruption rates as a reliability index. Today, however, many electricity consumers are adversely affected by more subtle voltage disturbances such as harmonic distortion. This paper deals with observations of events that occur in the Dimmer circuits and phase control which could affect harmonics problem to the commercial power system. In order to reduce the effect of harmonics and design filters, Solid State Relay Dimmer(SCRs or TRIACs) and Noise Filter are described, and the effects of harmonics is also analyzed. IGBT Dimmer which is appropriate method to reduce harmonics and improve efficiency is introduced.

• Journal of Power Electronics
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• v.18 no.2
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• pp.323-331
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• 2018

Buck power factor correction (PFC) converters, compared with conventional boost PFC converters, exhibit high efficiency performance in the entire range of universal line voltage. This feature has gotten more attention for eliminating the zero crossing dead angle of buck PFC rectifiers. Furthermore, bridgeless structures for the reduction of conduction losses have been proposed. The aim of this paper is to introduce a single-phase buck rectifier that simultaneously has unity power factor (PF) and bridgeless structure while operating in the continuous conduction mode (CCM). For this purpose, two auxiliary flyback converters without any active switches are applied to a bridgeless buck rectifier to eliminate the zero crossing dead angle and achieve unity power factor, low total harmonic distortion (THD) and high efficiency. The operation and design considerations of the proposed rectifier are verified on a 150W, 48V prototype using a conventional peak-current-mode control. The measurement results show that the proposed rectifier has nearly unity power factor, THD less than 7% and high efficiency.