• 제목/요약/키워드: Short pulses injection

검색결과 8건 처리시간 0.017초

극성 판별이 가능한 최소 제곱법 기반의 IPMSM 회전자 초기 위치 추정 (Initial Rotor Position Estimation of an IPMSM Based on Least Squares Approximation with a Polarity Identification)

  • 김건영;박영수;이교범
    • 전력전자학회논문지
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    • 제23권1호
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    • pp.72-75
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    • 2018
  • An initial rotor position estimation method is proposed in this study for an interior permanent-magnet synchronous motor without a resolver or an absolute encoder. This method uses least squares approximation to estimate the initial rotor position. The magnetic polarity is identified by injection of short pulses. The proposed estimation process is robust because it does not require complex signal processing that depends on the performance of a digital filter. In addition, it can be applied to various servo systems because it does not require additional hardware. Experimental results validate the effectiveness of the proposed method using a standard industrial servomotor with interior-permanent magnets.

광주입 방법을 이용한 밀리미터파 신호 생성 (Optical Millimeter-wave Signal Generation using Injection Locking Scheme)

  • Kim, Jung-Tae
    • 한국정보통신학회논문지
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    • 제7권5호
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    • pp.1076-1081
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    • 2003
  • 본 논문에서는 반도체레이저를 이용한 밀리미터파 대역의 신호를 생성하는 방법에 대해 제안하였다. 광대역에서의 밀리미터파 신호를 얻기 위해서는 윈하는 공진 주파수대역의 신호를 얻기 위해는 서브 하모닉의 좁은 신호 성분의 하모닉 신호인 다중의 신호를 서로 beating하여 원하는 주파수 대역의 신호를 얻을 수 있다. 따라서 본 논문에서는 반도체레이저를 사용한 광주입 방법을 통하여 실제적으로 원하는 주파수 대역의 신호를 얻기 위해 실험적으로 고찰하였으며, 신호 성분의 성능을 구하기 위해 phase noise 성분을 측정하였다.

흡수격자를 갖는 DFB 레이저의 제작 및 특성 (Fabrication and Characteristics of DFB Laser with Absorption Grating)

  • 이형종
    • 한국광학회:학술대회논문집
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    • 한국광학회 1990년도 제5회 파동 및 레이저 학술발표회 5th Conference on Waves and lasers 논문집 - 한국광학회
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    • pp.73-78
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    • 1990
  • 1.3${\mu}{\textrm}{m}$ DFB with absorption grating of 1.55${\mu}{\textrm}{m}$ InGaAsP layer was fabricated. This new type of DFB laser shows self-plusation for DC operation. At low level of injection the relation between the pulsation frequency and the injection current shows similar behavior with the relaxation oscillation of ordinary laser and at high level of injection the pulsation frequency decreases compared to the relaxation oscillation. Period doubling, period 3 and 4 were observed for AC modulation. In case of period doubling the waveform shows only one pulse within a period without any accompanying subsidiary pulses and the oscillation frequency was quite stable. The pulse widths as short as 58.5 ps was achieved with AC modulation. We propose the time division multiplexing application of this kind of DFB laser.

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Simulations for the cesium dynamics of the RF-driven prototype ion source for CRAFT N-NBI

  • Yalong Yang;Yong Wu;Lizhen Liang;Jianglong Wei;Rui Zhang;Yahong Xie;Wei Liu;Chundong Hu
    • Nuclear Engineering and Technology
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    • 제56권4호
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    • pp.1145-1152
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    • 2024
  • To realize an initial objective of the negative ion-based neutral beam injection (N-NBI) at the Comprehensive Research Facility for Fusion Technology (CRAFT) test facility, which targets an H0 beam power of 2 MW at an energy of 200-400 keV and a pulse duration of 100 s, it is crucial to study the cesium dynamics of the negative ion source. Here a numerical simulation program CSFC3D is developed and applied to simulate the distribution and time dynamics of cesium during short pulses. The calculations show that most of the cesium on the plasma grid (PG) area originates from the release of cesium that is accumulated within the ion source in the plasma phase. Increasing the wall temperature reduces the loss of cesium on the wall of the ion source. Furthermore, the thickness of the cesium monolayer is directly influenced by the PG temperature. Both simulated and experimental results demonstrate that maintaining the PG temperature between 180 ℃ and 200 ℃ is essential for enhancing the performance of the ion source and optimizing the cesium behavior.

Frequency-dependent grounding impedance of the counterpoise based on the dispersed currents

  • Choi, Jong-Hyuk;Lee, Bok-Hee;Paek, Seung-Kwon
    • Journal of Electrical Engineering and Technology
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    • 제7권4호
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    • pp.589-595
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    • 2012
  • When surges and electromagnetic pulses from lightning or power conversion devices are considered, it is desirable to evaluate grounding system performance as grounding impedance. In the case of large-sized grounding electrodes or long counterpoises, the grounding impedance is increased with increasing the frequency of injected current. The grounding impedance is increased by the inductance of grounding electrodes. This paper presents the measured results of frequency-dependent grounding impedance and impedance phase as a function of the length of counterpoises. In order to analyze the frequency-dependent grounding impedance of the counterpoises, the frequency-dependent current dissipation rates were measured and simulated by the distributed parameter circuit model reflecting the frequency-dependent relative resistivity and permittivity of soil. As a result, the ground current dissipation rate is proportional to the soil resistivity near the counterpoises in a low frequency. On the other hand, the ground current dissipation near the injection point is increased as the frequency of injected current increases. Since the high frequency ground current cannot reach the far end of long counterpoise, the grounding impedance of long counterpoise approaches that of the short one in the high frequency. The results obtained from this work could be applied in design of grounding systems.

직류전류 주입법에 의한 벡터제어 유도전동기의 회전자 시정수 보상 (Rotor Time Costant Compensation for Vector-Controlled IM with DC Current Injection Method)

  • 이경주;남현택;최종우;김홍근;이득기;전태원;노의철
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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    • pp.285-287
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    • 2001
  • To obtain a high performance in a vector controlled induction machine, it is essential to know the instantaneous position of the rotor flux which depends on the rotor time constant. But the rotor time constant mainly varies due to the temperature rise in the motor winding, so real time compensating algorithm is necessary. This paper proposes that it uses short duration pulses added to the constant flux command current and then resultant torque command current produced by speed controller is utilized for the rotor resistance estimation. This method has advantages with a low computational requirement and does not require voltage sensors. The proposed method is proved by simulations.

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직류전류 주입법에 의한 벡터제어 유도전동기의 회전자 시정수 보상 (Rotor Time Constant Compensation for Vector-Controlled Induction Motor with DC Current Injection Method)

  • 이경주;이득기;정종진;최종우;김흥근;노의철;전태원
    • 대한전기학회논문지:전기기기및에너지변환시스템부문B
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    • 제51권2호
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    • pp.69-76
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    • 2002
  • To obtain a high performance in a vector controlled induction motor, it is essential to know the instantaneous position of the rotor flux which depends on the rotor time constant. But the rotor time constant mainly varies due to the temperature rise in the motor winding, so real time compensating algorithm is necessary. This paper proposes that it uses short duration pulses added to the constant flux command current and then resultant torque command current produced by speed controller is utilized for the rotor resistance estimation. This method has advantage with a low computational requirement and does not require voltage sensors. The proposed method is proved by simulations and experimentals.

MREIT Conductivity Imaging of Pneumonic Canine Lungs: Preliminary Post-mortem Study

  • Kim, Hyung-Joong;Kim, Young-Tae;Jeong, Woo-Chul;Minhas, Atul S.;Lee, Tae-Hwi;Lim, Chae-Young;Park, Hee-Myung;Kwon, O-Jung;Woo, Eung-Je
    • 대한의용생체공학회:의공학회지
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    • 제31권2호
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    • pp.94-98
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    • 2010
  • In magnetic resonance electrical impedance tomography (MREIT), a current-injection MR imaging method is adopted to produce a cross-sectional image of an electrical conductivity distribution in addition to MR images. The purpose of this study was to test the feasibility of MREIT for differentiating the canine lung parenchyma without and with pneumonia. Three normal healthy beagles and two mixed breed dogs with pneumonia were used. After attaching electrodes around the chest, we placed the dog inside our MR scanner. We injected as much as 30 mA current in a form of short pulses into the chest region. Reconstructed conductivity images of normal canine lungs exhibit a peculiar pattern of a relatively coarse salt and pepper noise. On the contrary, conductivity images of pneumonic canine lungs show significantly enhanced contrast of the lesions while the corresponding MR images show a little bit of contrast in the middle and caudal lung parenchyma due to the accumulation of pleural fluid. This preliminary study indicates that MREIT imaging of the chest may deliver unique new diagnostic information.