• Title, Summary, Keyword: space harmonic analysis

Search Result 146, Processing Time 0.043 seconds

Solar Cyclic Modulation of Diurnal Variation in Cosmic Ray Intensity

  • Park, Eun Ho;Jung, Jongil;Oh, Suyeon;Evenson, Paul
    • Journal of Astronomy and Space Sciences
    • /
    • v.35 no.4
    • /
    • pp.219-225
    • /
    • 2018
  • Cosmic rays are ions that move at relativistic speeds. They generate secondary cosmic rays by successive collisions with atmospheric particles, and then, the secondary particles reach the ground. The secondary particles are mainly neutrons and muons, and the neutrons are observed by the ground neutron monitor. This study compared the diurnal variation in cosmic ray intensity obtained via harmonic analysis and that obtained through the pile-up method, which was examined in a previous study. In addition, we analyzed the maximum phase of the diurnal variation using four neutron monitors with a cutoff rigidity below approximately 6 GV, located at similar longitudes to the Oulu and Rome neutron monitors. Expanding the data of solar cycles 20-24, we examined the time of the maximum cosmic ray intensity, that is, the maximum phase regarding the solar cyclic modulation. During solar cycles 20-24, the maximum phase derived by harmonic analysis showed no significant difference with that derived by the pile-up method. Thus, the pile-up method, a relatively straightforward process to analyze diurnal variation, could replace the complex harmonic analysis. In addition, the maximum phase at six neutron monitors shows the 22-year cyclic variation very clearly. The maximum phase tends to appear earlier and increase the width of the variation in solar cycles as the cutoff rigidity increases.

Design of small slotless BLDC motor for robot using Space Harmonic Analysis Method (공간 고조파 해석 기법을 이용한 로봇용 소형 Slotless BLDC Motor 설계)

  • Kim, Hong-Seok;Kim, Sung-Jin;Kang, Gyu-Hong
    • Proceedings of the KIEE Conference
    • /
    • /
    • pp.1132-1134
    • /
    • 2005
  • This paper presents a design strategy of Slotless type BLDC motor using the space harmonic field method. The distribution of Back emf and torque are considered by movement of the Permanent Magnet and armature current. The result of magnetic field distribution, back-emf, and torque are in agreement with FEM.

  • PDF

Eddy Current Loss Analysis of Slotless Double-sided Cored Type Permanent Magnet Generator by using Analytical Method (해석적 방법을 이용한 슬롯리스 양측식 코어드 타입 영구자석 발전기의 와전류 손실 해석)

  • Jang, Gang-Hyeon;Jung, Kyoung-Hun;Hong, Keyyong;Kim, Kyong-Hwan;Choi, Jang-Young
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.65 no.10
    • /
    • pp.1639-1647
    • /
    • 2016
  • This paper deals with eddy current loss analysis of Slotless Double sided Cored type permanent magnet linear generator by using analytical method, space harmonic method. In order to calculate eddy current, this paper derives analytical solution by the Maxwell equation, magnetic vector potential, Faraday's law and a two-dimensional(2-D) cartesian coordinate system. First, we derived the armature reaction field distribution produced by armature wingding current. Second, by using derived armature reaction field solution, the analytical solution for eddy current density distribution are also obtained. Finally, the analytical solution for eddy current loss induced in permanent magnets(PMs) are derived by using equivalent, electrical resistance calculated from PMs volume and eddy current density distribution solution. The analytical result from space harmonic method are validated extensively by comparing with finite element method(FEM).

Analysis of Single-phase Induction Motor Having Space Harmonics in Its Magnetic Field (고주파자속을 고려한 단순상유도전동기의 해석)

  • Keung Yul Oh
    • 전기의세계
    • /
    • v.22 no.3
    • /
    • pp.25-34
    • /
    • 1973
  • In this paper, the characteristics of a single phase induction motor which is considered the space harmonic flux by the double revolving field theory is analysed. As the rotor resistance for the fundamental flux is separated from the resistance for the rotor bar and end-ring, and the rotor leakage reactnace is separated from the skew leakage reactance and the other, so the circuit constants for the space harmonic flux is expressed by the circuit constants for the fundamentals. As the ratio of the circuit constants for the magnetizing reactance is used, the generalized equivalent circuit is made up. the characteristic equation which is able to analysis the subdivided characteristics by the above circuit is induced. The ratio of the circuit constants and the skew angle being changed, the variations of the torque-speed characteristics for the fundamentals and harmonics is examined by this equation.

  • PDF

Design and Characteristics Analysis of the 78 kWe Grade Synchronous Generator for Disused Diesel Engines

  • Youn, Jun-Seop;Kim, Hae-Joong;Kim, Youn-Hwan;Moon, Jae-Won
    • Journal of Magnetics
    • /
    • v.22 no.1
    • /
    • pp.122-132
    • /
    • 2017
  • This study dealt with the design process of the 78 kW permanent magnet synchronous generator for engines. After the calculation of the basic dimensions through a theoretical method in the process of initial model design, FEA (finite-element analysis) and a d,q-axis equivalent circuit were used to identify the generator characteristics depending on the number of poles. With the use of the space harmonic analysis method, the back-EMF (electromotive force) and THD were checked, and then the number of slots was determined. In addition, the most optimized generator dimensions were determined through a sizing optimization technique. Based on this, the optimum model with enhanced efficiency, material costs, and temperature characteristics was derived, and the availability of the design method was confirmed through a comparative analysis of the initial and optimum models.

A Novel Method of the Harmonic Analysis by Using the Multi-Carrier PWM Techniques in the Multi-Level Inverter (멀티 레벨 인버터에서 멀티 캐리어 PWM 방법을 사용한 고조파 분석의 새로운 방법)

  • Kim June-Sung;Kim Tae-Jin;Kang Dae-Wook;Hyun Dong-Seok
    • Proceedings of the KIPE Conference
    • /
    • /
    • pp.171-174
    • /
    • 2002
  • This paper deals with a novel method in order to analyze the harmonic characteristics in the multi-level inverter. Generally, the magnitude of harmonic components is different according to the carrier PWM techniques, modulation Index(Mi), and the level of multi-level inverter The previous papers analyzed the harmonic characteristics from the viewpoint of the space vector. Hence, the calculation of the harmonic vector becomes difficult and complex in 4-level or more than S-level. However, the proposed method of this paper reduced an amount of calculation and simplified the process of calculation by using the relationship between reference voltage and output phase voltage to load neutral. This paper analyzed the harmonic and it is applied to the multi-carrier PWM techniques in 5- level and other-level of cascaded inverter system.

  • PDF

The Harmonic Reduction Design of IPMSM No-load line-line Back-EMF for ISG (ISG용 매입형 영구자석 동기 전동기 무부하 선간 역기전력 고조파 저감설계)

  • Lee, Jin-Gyu;Jung, Jae-Woo;Kim, Sung-Il;Hong, Jung-Pyo
    • Proceedings of the KIEE Conference
    • /
    • /
    • pp.754-755
    • /
    • 2008
  • This paper presents a method for reducing the Total Harmonic Distortion(THD) of line-line back_EMF of the IPMSM with distributed winding under the no-load condition. Firstly, the specific harmonic components of line-line back EMF are reduced considering with winding factor. Secondly, THD of line-line back EMF is minimized according to change of pole angle using by Space harmonic Analysis. Finally, the optimal design for minimizing the THD is conducted using response surface methodology with finite element analysis. The validity of the design method dealt with in this paper is demonstrated by comparison between the THD of optimal model and initial model.

  • PDF

A Study on the Novel Space Vector Based Harmonic Elimination Method of Inverter (인버터 고조파 저감을 위한 새로운 공간벡터 변조기법에 관한 연구)

  • Lee, Sang-Taik;Kim, Hee-Jun;Oh, Won-Seok;Shin, Tae-Hyun
    • Proceedings of the KIEE Conference
    • /
    • /
    • pp.1236-1238
    • /
    • 2000
  • This paper considers the problem of eliminating harmonics in the inverter output waveforms. The approach is based on the minimization of the current harmonics in the induction motor by space vector modulation method. Reference voltage is compensated with injection of controlled current harmonics which are calculated to reduce current harmonics through sampled current harmonic analyzing algorithm. The theoretical analysis is carried out using computer simulation. It is verified that proposed SVM technique could reduce current harmonic component and improve THD.

  • PDF

Modal Analysis on SPL of the Periodic Structure depend on Unsymmetrical Beam Space (비대칭형 보강재 간격에 따른 주기구조물의 SPL모드 해석)

  • 김택현;김종태
    • Transactions of the Korean Society of Machine Tool Engineers
    • /
    • v.11 no.1
    • /
    • pp.52-60
    • /
    • 2002
  • The purpose of this research is to study the vibration and acoustic pressure radiation from a thin isotropic flat plate stiffened by a rectangular array of beams, and excited by a time harmonic point force. These constructions on aircraft and ship structures are often subjected to fiequency dependent pressure fluctuations and forces. Forces from the these excitations induce structural vibrations in a wide range of fiequencies, which may cause such things as acoustic fatigue and internal cabin noise in the aircraft. It is thus important that the response characteristics and vibration modes of such periodic structures be horn. From this theoretical model, the sound pressure levels(SPL) in a semi-infinite fluid(water) bounded by the plate with the variation in the locations of an external time harmonic point farce on the plate can be calculated efficiently using three numerical tools such as the Gauss-jordan method the LU decomposition method md the IMSL numerical package.