• Title, Summary, Keyword: space harmonic analysis

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Dynamic Analysis of Slotless Permanent Magnet Linear Synchronous Motor using the 3-D Space Harmonic Method

  • Ahn, Ho-Jin;Kang, Gyu-Hong;Kim, Gyu-Tak
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • v.2B no.4
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    • pp.162-167
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    • 2002
  • This paper presents the dynamic analysis method for a slotless permanent magnet linear synchronous motor (PMLSM) using the 3-D space harmonic method. Instantaneous emf and thrust are considered by movement of the PM and instantaneous armature current instead of $K_E$ (back-emf constant) and $K_F$(thrust force constant) for accurate results. The results of magnetic field distribution, back-emf, inductance, and thrust are in agreement with 2-D FEM and experimental results. To confirm the validity of this method, the calculated results are compared to measured ones.

State-Space Analysis on The Stability of Limit Cycle Predicted by Harmonic Balance

  • Lee, Byung-Jin;Yun, Suk-Chang;Kim, Chang-Joo;Park, Jung-Keun;Sung, Sang-Kyung
    • Journal of Electrical Engineering and Technology
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    • v.6 no.5
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    • pp.697-705
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    • 2011
  • In this paper, a closed-loop system constructed with a linear plant and nonlinearity in the feedback connection is considered to argue against its planar orbital stability. Through a state space approach, a main result that presents a sufficient stability criterion of the limit cycle predicted by solving the harmonic balance equation is given. Preliminarily, the harmonic balance of the nonlinear feedback loop is assumed to have a solution that determines the characteristics of the limit cycle. Using a state-space approach, the nonlinear loop equation is reformulated into a linear perturbed model through the introduction of a residual operator. By considering a series of transformations, such as a modified eigenstructure decomposition, periodic averaging, change of variables, and coordinate transformation, the stability of the limit cycle can be simply tested via a scalar function and matrix. Finally, the stability criterion is addressed by constructing a composite Lyapunov function of the transformed system.

Torque Density Improvement of Five-Phase PMSM Drive for Electric Vehicles Applications

  • Zhao, Pinzhi;Yang, Guijie
    • Journal of Power Electronics
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    • v.11 no.4
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    • pp.401-407
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    • 2011
  • In order to enhance torque density of five-phase permanent magnetic synchronous motor with third harmonic injection for electric vehicles (EVs) applications, optimum seeking method for injection ratio of third harmonic was proposed adopting theoretical derivation and finite element analysis method, under the constraint of same amplitude for current and air-gap flux. By five-dimension space vector decomposition, the mathematic model in two orthogonal space plane, $d_1-q_1$ and $d_3-q_3$, was deduced. And the corresponding dual-plane vector control method was accomplished to independently control fundamental and third harmonic currents in each vector plane. A five-phase PMSM prototype with quasi-trapezoidal flux pattern and its fivephase voltage source inverter were designed. Also, the dual-plane vector control was digitized in a single XC3S1200E FPGA. Simulation and experimental results prove that using the proposed optimum seeking method, the torque density of five-phase PMSM is enhanced by 20%, without any increase of power converter capacity, machine size and iron core saturation.

OBSERVATIONS OF TERRESTRIAL NIGHTGLOW (MEINEL BANDS) AT KING SEJONG STATION, ANTARCTICA

  • Won, Young-In;Cho, Young-Min;Lee, Bang-Yong;Kim, Jhoon;Chung, Jong-Kyun;Kim, Yong-Ha
    • Journal of Astronomy and Space Sciences
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    • v.16 no.2
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    • pp.149-158
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    • 1999
  • A Fourier Transform Spectrometer was used to study upper mesospheric thermodynamic by observing the hydroxyl(OH) emission. Rocket-born and satellited-born photometers place the peak emission near 87 km. The instrument was installed in February 1999 at King Sejong station ($62.22^{circ}S,301.25^{circ}E$), Antarctica and has been in routine operation since then. An intensive operational effort has resulted in a substantial data between April and June, 1999. A harmonic analysis was carried out to examine information on the tidal characteristics. The measured amplitudes of the 12-hour oscillation are in the range of 2.4-3.7 K, which are in resonable agreement with theoretical model outputs. The harmonic analysis also revealed 8-hour oscillation which is not expected from the traditional theoretical studies. In addition, the observed 8-hour oscillations are apparent and sometimes dominate the temperature variation in the upper mesosphere.

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Effects of High-harmonic Components on the Rayleigh Indices in Multi-mode Thermo-acoustic Combustion Instability

  • Song, Chang Geun;Yoon, Jisu;Yoon, Youngbin;Kim, Young Jin;Lee, Min Chul
    • International Journal of Aeronautical and Space Sciences
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    • v.17 no.4
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    • pp.518-525
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    • 2016
  • This paper presents the characteristics of non-fundamental multi-mode combustion instability and the effects of high-harmonic components on the Rayleigh criterion. Phenomenological observations of multi-harmonic-mode dynamic pressure waves regarding the intensity of harmonic components and the source of wave distortion have been explained by introducing examples of second- and third-order harmonics at various amplitudes. The amplitude and order of the harmonic components distorted the wave shapes, including the peak and the amplitude, of the dynamic pressure and heat release, and consequently the temporal Rayleigh index and its integrals. A cause-and-effect analysis was used to identify the root causes of the phase delay and the amplification of the Rayleigh index. From this analysis, the skewness of the dynamic pressure turned out to be a major source in determining whether multi-mode instability is driving or damping, as well as in optimizing the combustor design, such as the mixing length and the combustor length, to avoid unstable regions. The results can be used to minimize errors in predicting combustion instability in cases of high multi-mode combustion instability. In the future, the amount of research and the number of applications will increase because new fuels, such as fast-burning syngases, are prone to generating multi-mode instabilities.

Space Harmonic Field by Interaction of Stator and Rotor Slots (고정자 슬롯과 회전자 슬롯의 상호작용에 의한 공간 고조파)

  • Lee, Eun-Woong;Cho, Hyun-Gil;Kim, Jong-Gyeum;Jeong, Jong-Ho;Kim, Il-Jung
    • Proceedings of the KIEE Conference
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    • pp.42-45
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    • 1995
  • This paper describes the flux density in air gap, harmonic torques occurring by inadequate slot combination of induction motor using the fourier series. The analysis uses DFT(Discrete Fourier transform) to analyze harmonic orders of flux density. It is certified that the harmonic flux density has the same result using Fourier series and FEM.

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A Study on Sound Radition from the Periodic Structure depend on Symmetrical beam space Using FEM (FEM을 이용한 대칭형 보강재에 보강된 평판의 음향방사에 관한 연구)

  • Kim J.T.;Kim T.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.732-739
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    • 2005
  • The determination of sound pressure radiated from periodic plate structures is fundamental in the estimation of noise level in aircraft fuselages or ship hull structures. As a robust approach to this problem, here a very general and comprehensive analytical model is developed for predicting the sound radiated by a vibrating plate stiffened by periodically spaced orthogonal symmetrical beams subjected to a sinusoidally time varying point load. In this these, we experiment with the numerical analysis using the space harmonic series and the SYSNOISE for measuring the vibration mode and character of response caused by sound radiation with adding the harmonic point force in the thin isotropic plate supported by the rectangular lattice reinforcement. We used the reinforcements, beams of open type section like the style of 'ㄷ' letter; the space of the beams were chosen to be 0.2m, 0.3m, 0.4m. We studied the behavior of sound pressure levels, analysis of vibration mode between support points, connection between frequency function and sound pressure levels, and connection between position function and sound pressure levels.

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Static and Dynamic Instability Characteristics of Thin Plate like Beam with Internal Flaw Subjected to In-plane Harmonic Load

  • R, Rahul.;Datta, P.K.
    • International Journal of Aeronautical and Space Sciences
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    • v.14 no.1
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    • pp.19-29
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    • 2013
  • This paper deals with the study of buckling, vibration, and parametric instability characteristics in a damaged cross-ply and angle-ply laminated plate like beam under in-plane harmonic loading, using the finite element approach. Damage is modelled using an anisotropic damage formulation, based on the concept of reduction in stiffness. The effect of damage on free vibration and buckling characteristics of a thin plate like beam has been studied. It has been observed that damage shows a strong orthogonality and in general deteriorates the static and dynamic characteristics. For the harmonic type of loading, analysis was carried out on a thin plate like beam by solving the governing differential equation which is of Mathieu-Hill type, using the method of multiple scales (MMS). The effects of damage and its location on dynamic stability characteristics have been presented. The results indicate that, compared to the undamaged plate like beam, heavily damaged beams show steeper deviations in simple and combination resonance characteristics.

Space Harmonic Analysis of PM type LSM taking into account Slot by Equivalent Magnetizing Current (등가자화전류를 이용한 영구자석형 선형동기전동기의 슬롯을 고려한 공간고조파해석)

  • Jo, Jae-Ok;Kang, Gyu-Hong;Hong, Jung-Pyo;Kim, Gyu-Tak
    • Proceedings of the KIEE Conference
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    • pp.192-194
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    • 1997
  • This paper propose an efficient space harmonic analysis method for magnetic field. Permanent magnet and primary core considered slot are replaced by EMC(equivalent magnetizing current). And the resultant air gap flux density is calculated by superposition due to the permanent magnet and EMC. We analyze the harmonic distribution of air gap flux density taking into account slot for PMLSM.

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Analysis and simulation of Cascaded H-bridge 7 level inverter for eliminating typical harmonic waveforms (특정 고조파 제거를 위한 Cascaded H-bridge 7레벨 인버터의 특성해석 및 시뮬레이션)

  • Jin, Sun-Ho;Oh, Jin-Suk;Jo, Kwan-Jun;Kwak, Jun-Ho;Lim, Myoung-Kyu;Kim, Jang-Mok
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • pp.1022-1028
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    • 2005
  • This paper is presented the analysis results and simulation results of cascaded H-bridge 7 level inverter with various modulation index. Stepped waveform having number of switching was used to eliminate harmonic components. Switching angles according to modulation index are calculated numerically. Therefore, 3 times of switching with 7 level topology and QWS(Quarter Wave Symmetry) could eliminate 5th and 7th harmonics. The harmonic characteristics are compared to those of space vector modulation method which known as common modulation method in industrial field. Stepped waveform method showed higher ability to reduce, especially lower order of harmonics.

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