• Title/Summary/Keyword: 2-Phase

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An Analysis of Noise Characteristics According to the Excitation Method of SRM (SRM의 여자방식에 따른 소음특성 해석)

  • Mun, Jae-Won;O, Seok-Gyu;An, Jin-U
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.49 no.9
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    • pp.565-571
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    • 2000
  • SRM has been applied to many commercial applications that require economical advantages and high performance abilities. But it has some drawbacks such as acoustic noise due to the abrupt change of mmf level when commutation. The abrupt change of a phase excitation produces mechanical stresses and it results in torque ripple and noise. This paper deals with an analysis of vibration and noise in SRM drive. Several types of excitation method are taken into account. The 1-phase and 2-phase excitation technique of short-pitch winding 2-phase excitation technique of full-pitch winding are tested. The acoustic noise is reduced remarkably through the sequential phase excitation in the 2-phase excitation. It is because that the scheme reduces abrupt change of excitation level by distributed balanced excitation with free-wheeling during commutation.

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A Design Study of Phase Detectors for the 2.5 Gb/s Clock and Data Recovery Circuit (2-5 Gb/s 클럭-데이터 복원기를 위한 위상 비교기 설계 연구)

  • 이영미;우동식;유상대;김강욱
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • 2002.11a
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    • pp.394-397
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    • 2002
  • A design study of phase detectors for the 2.5 Gb/s CDR circuit using a standard 0.18-${\mu}{\textrm}{m}$ CMOS process has been performed. The targeted CDR is based on the phase-locked loop and thus it consists of a phase detector, a charge pump, a LPF, and a VCO. For high frequency operation of 2.5 Gb/s, phase detector and charge pump, which accurately compare phase errors to reduce clock jitter, are critical for designing a reliable CDR circuit. As a phase detector, the Hogge phase detector is selected but two transistors are added to improve the performance of the D-F/F. The charge pump was also designed to be placed indirectly input and output.

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Novel Driving System of 2-Phase Induction Motor Driven with Voltage Source Inverter (인버어터 구동 2상 유도 전동기의 새로운 구동 방식에 관한 연구)

  • Jang, Do-Hyun
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.38 no.7
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    • pp.481-491
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    • 1989
  • A compensation strategy for the phase-difference control method, which has been reported as a new driving method of a 2-phase inverter-fed induction motor, is proposed. The phase-difference control method extends the control range of the speed and eliminates the harmonic contents of the output voltage of the 2-phase inverter-fed induction motor. However, the phase-difference angle becomes narrower, motor efficiency deceases more and pulsating torque increases more. As the counterplan for these shortcomings of the phase-difference control method, a hybrid control method which combines the phase-difference control with the voltage control is proposed. The algorithm to realize a hybrid method is presented. As an example, a model composed of 5 regions has been analyzed by computer simulation in terms of motor performance and the results have been compared with experimental results.

Phase Transition Properties of Ferroelectric Polymer Films (강유전 고분자 박막의 상전이 특성)

  • Park, Chul-Woo;Jung, Chi-Sup
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.27 no.2
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    • pp.97-103
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    • 2014
  • Phase transition properties of the copolymer films of polyvinylidene fluoride (PVDF) and trifluoroethylene(TrFE), P(VDF-TrFE), were studied with X-ray diffraction (XRD) and polarization modulated ellipsometry (PME). XRD studies on both Langmuir-Blodgett (LB) films and spin coated films exhibit conversions from ferroelectric phase to paraelectric phase at $108{\pm}2^{\circ}C$ on heating and paraelectric phase to ferroelectric phase at $78{\pm}2^{\circ}C$ on cooling. The presence of the ferroelectric-paraelectric phase transition is also confirmed by the PME technique for the first time in this study. PME was proved to be a very sensitive tool in the measurement of the structural changes at the nano-thickness films.

A Performance Comparison of Excitation Strategies For a Low Noise SRM Drive

  • Lee Dong-Hee;Kim Tae-Hyoung;Ahn Jin-Woo
    • Journal of Power Electronics
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    • v.5 no.3
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    • pp.218-223
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    • 2005
  • A simple construction, low cost, and a fault tolerant power electronic drive have made the switched reluctance drive a strong contender for many applications. But the switched reluctance drive exhibits higher levels of vibration and acoustic noise than most competing drives. The main source of vibration in the switched reluctance drive is generated by the rapid change of radial magnetic force when the phase current is extinguished during commutation. In this paper, some excitation methods are proposed to reduce the vibration and acoustic noise of the switched reluctance drive. The excitation strategies considered in this research are 1-phase, 2-phase and hybrid excitation methods. The 1-phase method is the conventional approach, while in the 2-phase method, the two phases are excited simultaneously. The hybrid excitation has 2-phase excitation using a long dwell angle as well as conventional 1-phase excitation. The vibration and acoustic noise are compared and tested. The suggested 2-phase and hybrid strategies reduce acoustic noise because the schemes reduce the abrupt change in excitation level by using distributed and balanced excitation.

A Study on Phase Bearing Error using Phase Delay of Relative Phase Difference

  • Lee, Kwan Hyeong
    • International Journal of Internet, Broadcasting and Communication
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    • v.13 no.2
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    • pp.76-81
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    • 2021
  • This study proposes a method to reduce the phase error of the received signal to detect the object bearing. The phase shift of the received signal occurs due to the multipath of the signal by natural structure or artificial structures. When detecting the direction of the object using radio waves, the phase of the received signal cannot be accurately detected because of the phase bearing error in the object detection direction. The object detection direction estimation depends on the phase difference, antenna installation distance, signal source wavelength, frequency band and bearing angle. This study reduces the error of the phase bearing by using the phase delay of the relative phase difference for the signals incident on the two antennas. Through simulation, we analyzed the object direction detection performance of the proposed method and the existing method. Three targets are detected from the [-15°, 0°, 15°] direction. The existing method detects the target at [-13°, 3°, 17°], and the proposed method detects the at [-15°, 0°, 15°]. As a result of the simulation, the target detection direction of the proposed method is improved by 2 degrees compared to the existing method.

Structural Studies of $A^{2+}$(Mg$_{1/3}$Nb$_{2/3}$)O$_3$,(A$^{2+}$=Sr$^{2+}$ and $Ca^{2+}$) Ceramics using High Resolution Transmission Electron Microscopy (고분해능 투과전자현미경을 이용한 $A^{2+}$(Mg$_{1/3}$Nb$_{2/3}$)O$_3$,(A$^{2+}$=Sr$^{2+}$ and $Ca^{2+}$) 세라믹스의 구조연구)

  • Ryu, Hyun;Nahm, Sahn;Byun, Jae-Dong;Lee, Hwack-Joo;Park, Hyun-Min
    • Journal of the Korean Ceramic Society
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    • v.36 no.7
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    • pp.762-766
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    • 1999
  • The crystal structure of A2+(Mg1/3Nb2/3)O3,(A2+=Sr2+ and Ca2+)ceramics was studied usig X-ray diffraction (XRD) and high resolution transmission electrion microscopy(HRTEM). Ba(Mg1/3Nb2/3)O3 (SMN) has the 1:2 ordered monoclinic structure which has the anti-phase tilt of octahedra. The type of tilting in SMN was considered to be a$^{\circ}$a$^{\circ}$c- or a­a­c$^{\circ}$ Ca(Mg1/3Nb2/3)O3 (CMN) also has the 1:2 ordered monoclinic structure which was distorted by the anti-phase tilt or in-phsae tilt of octahedra. A unit cell containing both the in-phase tilt axis and anti-phase tilt axis was not observed in the CMN. Therefore CMN has the mixed phase consisting of the 1:2 ordered monoclinic phase with anti-phase tilt of octahedra and the one with in -phase tilt of ocatahedra,. The anti-parallel shift of cation was also observed in the CMN.

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Study on the Growth of Monoclinic VO2 Phase Applicable for Thermochromic Ceramic Tile

  • Jung, DaeYong;Kim, Ungsoo;Cho, Wooseok
    • Journal of the Korean Ceramic Society
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    • v.52 no.5
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    • pp.361-365
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    • 2015
  • Vanadium dioxide ($VO_2$) of monoclinic phase exhibits Metal Insulator Phase Transition (MIPT) phenomenon involving a sharp change in electrical and optical properties at $68^{\circ}C$. Solution-based process is applied to form uniform $VO_2$ coating layer on ceramic tiles. This can selectively block the near-infrared light to possibly reduce the energy loss and prevent dew condensation caused by the temperature difference. Heat treatment conditions including temperature and dwell time were examined to obtain a monoclinic $VO_2$ single phase. Both rutile and monoclinic $VO_2$ phases were observed from in the tiles post-annealed below $700^{\circ}C$. Desired monoclinic $VO_2$ single phase was grown in the tiles heat treated at $750^{\circ}C$. Nano facets of irregular size were observed in the monoclinic $VO_2$ phase involving the phase-transition. Grain growth of monoclinic $VO_2$ phase was observed as a function of dwell time at $750^{\circ}C$.

Analysis on Properties of $TiO_2-Nb_2O_5$ Sol ($TiO_2-Nb_2O_5$ 솔의 물성에 대한 분석)

  • You, Do-Hyun
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.55 no.7
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    • pp.349-353
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    • 2006
  • [ $TiO_2-Nb_2O_5$ ] sol was prepared using sol-gel method. Crystalline properties of gel powder changed from rutile phase to anatase phase with increasing $Nb_2O_5$ additives at $800^{\circ}C$, while they retained rutile phase regardless of $Nb_2O_5$ additives at $900^{\circ}C,\;1,000^{\circ}C$. They retained amorphous phase from $50^{\circ}C\;to\;400^{\circ}C$, retained anatase phase from $500^{\circ}C\;to\;600^{\circ}C$ and had rutile phase over $700^{\circ}C$ at 1mole% $Nb_2O_5$ additive. After $TiO_2-Nb_2O_5$ sol retained low viscosity with normal chain structure for a long time, its viscosity increased fast with network structure. DTA properties of gel powder had endothermic reaction due to evaporation of propanol and water about $78^{\circ}C$, had exothermic reaction due to propanol combustion about $290^{\circ}C$ and had exothermic reaction due to changing of $TiO_2$ phase about $640^{\circ}C$.

Development of Site Characterization Technologies for Crystalline Rocks at Mizunami Underground Research Laboratory (MIU) - Surface-based Investigation Phase - (미즈나미 지하처분연구시설 결정질암에 대한 부지 특성규명 기술 개발 -지표기반 조사단계-)

  • Hama, Katsuhiro
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.11 no.2
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    • pp.115-131
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    • 2013
  • The Mizunami Underground Laboratory (MIU) Project is a comprehensive research project investigating the deep underground environment within crystalline rock being conducted by Japan Atomic Energy Agency. The MIU Project has three overlapping phases: Surface-based Investigation phase (Phase I), Construction phase (Phase II), and Operation phase (Phase III), with a total duration of 20 years. The overall project goals of the MIU Project from Phase I through to Phase III are: 1) to establish techniques for investigation, analysis and assessment of the deep geological environment, and 2) to develop a range of engineering for deep underground application. For the overall project goals 1), the Phase I goals were set to construct models of the geological environment from all surface-based investigation results that describe the geological environment prior to excavation and predict excavation response. For the overall project goals 2), the Phase I goals were set to formulate detailed design concepts and a construction plan for the underground facilities. This paper introduces geosynthesis procedures for the investigation and assessment of the hydrochemistry of groundwater in crystalline rock.