• Title, Summary, Keyword: phase error

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Direct Torque Control Scheme of Switched Reluctance Motor using Novel Torque Sharing Function (토크분배함수를 이용한 SRM의 적접토크제어기법)

  • Ahn, Jin-Woo;Lee, Dong-Hee;Kim, Tae-Hyoung;Liang, Jianing
    • Proceedings of the KIEE Conference
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    • pp.138-140
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    • 2007
  • A novel non-linear logical torque sharing function (TSF) is presented. To improve efficiency and to reduce torque ripple in commutation region, only a phase torque under commutation is regulated to produce a uniform torque. And the torque developed by the other phase remains with the previous state under a current limit of the motor and drive. If the minimum change of a phase torque reference can not satisfy the total reference torque, two-phase changing mode is used. Since a phase torque is constant and the other phase torque is changed at each rotor position, total torque error can be reduced within a phase torque error limit. And the total torque error is dependent on the change of phase torque. To consider non-linear torque characteristics and to suppress a tail current at the end of commutation region, the incoming phase current is changed to torque increasing direction, but the outgoing phase current is changed to torque decreasing direction. So, the torque sharing of the outgoing phase and incoming phase can be smoothly changed with a minimum current cross over. The proposed control scheme is verified by some computer simulations and experimental results.

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Digital Control of a Single-Phase UPS Inverter for Robust AC-Voltage Tracking

  • Woo Young-Tae;Kim Young-Chol
    • International Journal of Control, Automation, and Systems
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    • v.3 no.4
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    • pp.620-630
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    • 2005
  • This paper presents a digital controller for a single phase UPS inverter under two main considerations: (i) the overall system shall keep very low AC-voltage tracking error as well as no phase delay over different load conditions, and (ii) the digital controller shall be employed at a fixed sampling time. We propose that the former can be achieved by the proposed controller using the error-state approach and the latter can be dealt with by the socalled characteristics ration assignment.

Analysis of Optical Transfer Function and Phase Error of the Modified Triangular Interferometer

  • Kim, Soo-Gil;Ryeom, Jeong-Duk
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.1
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    • pp.10-18
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    • 2007
  • We synthesize and analyze the optical transfer function(OTF) of the modified triangular interferometer(MTI) using two-pupil synthesis method and we present the optimal MTI, which can obtain any bipolar function by combining a wave plate and a linear polarizer. Also, we analyze its potential phase error sources caused by polarization components.

Correction of Mean Phase Error for OFDM and SC-CP Systems using Decision-Directed Method (OFDM 및 SC-CP 시스템에 대한 결정지향 방식의 평균위상에러 정정)

  • Kim Ji-Heon;Kim Whan-Woo
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.42 no.12
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    • pp.77-84
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    • 2005
  • The orthogonal frequency division multiplexing (OFDM) technique and the single carrier with cyclic prefix (SC-CP) scheme are very attractive solutions for wireless applications, being computationally efficient since equalization is performed in the frequency domain. The equalizer could not entirely handle significant mean. Doppler shift. This motivates the use of a phase error tracking loop that operates jointly with the frequency equalizer. This paper describes the effect of the mean phase error and the performance of the proportional equalizer coupled with a phase error tracking loop based on decision-directed method. Furthermore, simulation results show that we can reduce the computational toad of the tracking loop with minimal performance degradation.

A Frequency Offset Compensation Technique for the High Order QAM using a Phase Differential Equation (고차 QAM에 적합한 위상 미분을 이용한 주파수 오차 보정 회로)

  • 박상열;윤태일;조경록
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.41 no.10
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    • pp.27-33
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    • 2004
  • In this paper, we present a carrier recovery circuit using the polarity-decision algorithm that recovers a phase and a frequency error simultaneously. The proposed algorithm catches a frequency error based on a differential of an angular velocity of the signal constellations. Using the differential of a phase error may compensate the frequency error. The symbol prediction method in the proposed algorithm accumulates the symbols, which makes easy to calculate a phase differential. The hardware size of the algerian is small since we use Q data or I only to get phase information. As a result, the algerian shows a pull-in range of normalized frequency error 0.5 under AWGN 15dB.

Phase error compensation for three-dimensional shape measurement based on a phase-shifting method (위상천이법을 이용한 삼차원 형상측정에서 위상오차 보정)

  • Park, Yoon-Chang;Ahn, Seong-Joon;Kang, Moon-Ho;Kwon, Young-Chul;Ahn, Seung-Joon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.10 no.11
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    • pp.3023-3030
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    • 2009
  • In this paper, a prediction and compensation method for the error in the phase measured by using the proportionality between two wavelengths in the TW-PMP (Two-wavelength Phase Measuring Profilometry) is proposed and experimental results are shown to verify the usefulness of the proposed method. For sample object, firstly, a phase-shifting with a quite large number of steps is adopted in measurement, compared with the conventional phase-shifting method, secondly, a 3-3 step phase-shifting method is used to measure the same object which is applied to high-speed 3D shape measurement, and then, measured results from these two phase-shifting methods are compared to calculate measurement noises. From the experimental results applying the proposed compensation method to the measured beat phase and absolute phase, it has proven that noises are decreased by 90% and 17.2% for each case.

Compensation Method of Current Measurement Error for Vector-Controlled Inverter of 2-Phase Induction Motor (2상 유도전동기용 벡터제어 인버터를 위한 전류측정 오차 보상 방법)

  • Lee, Ho-Jun;Yoon, Duck-Yong
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.7
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    • pp.1204-1210
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    • 2016
  • The phase currents must be accurately measured to achieve the instantaneous torque control of AC motors. In general, those are measured using the current sensors. However, the measured current signals can include the offset errors and scaling errors by several components such as current sensors, analog amplifiers, noise filter circuits, and analog-to-digital converters. Therefore, the torque-controlled performance can be deteriorated by the current measurement errors. In this paper we have analyzed the influence caused by vector control of 2-phase induction motor when two errors are included in measured phase currents. Based on analyzed results, the compensation method is proposed without additional hardware. The proposed compensation method was applied vector-controlled inverter for 2-phase induction motor of 360[W] class and verified through computer simulations and experiments.

Analysis of Phase Error Due to the Azimuth Angle of the Wave Plates in the Shearography Using Wollaston Prism (Wollaston prism을 이용한 스펙클패턴 전단간섭법에 있어서 파장판의 방위각에 의한 위상오차 해석)

  • Kim, Soo-Gil;Kim, Ki-Soo;Ko, Myung-Sook
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.19 no.8
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    • pp.1-7
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    • 2005
  • We introduced the method to obtain four speckle patterns with relative phase shift of ${\pi}/2$ by the polarizing elements, and calculate the phase at each point of the speckle pattern in shearography using Wollaston prism and polarizing elements. Ant we analyzed the phase error caused by the azimuth angles of wave plates used in the proposed method by Jones matrix.

Phase Error Analysis in Shearography Using Wave Plates (파장판를 이용한 스펙클패턴 전단간섭법에 있어서의 위상오차 해석)

  • Kim, Soo-Gil
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.19 no.1
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    • pp.34-39
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    • 2005
  • We presented the method to obtain four speckle patterns with relative phase shift of ${\pi}/2$ by passive devices such as wave plate and polarizer, and calculate the phase at each point of the speckle pattern in shearography using Wollaston prism. And, we analyzed the phase error caused by wave plates used in the proposed method by Jones matrix.

Bit Error Probability of $\pi$/4-DQPSK with Stepped Phase over a Frequency Selective Fading Channel (주파수선택성 페이딩전송로에서 스텝형 위상을 갖는 $\pi$/4-DQPSK의 비트오율)

  • 이철성;이재홍
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.32A no.9
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    • pp.1177-1183
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    • 1995
  • This paper proposes a new modulation scheme of $\pi$/4-DQPSK with stepped phase for a frequency selective fading channel. In the proposed modulation scheme, the phase of transmitted signal is shifted in the mid of a symbol duration in order to reduce the effect of multipath delay spread. It reduces the irreducible error of $\pi$/4-DQPSK over a frequency selective fading channel. It is shown that $\pi$/4-DQPSK with stepped phase achieves smaller average bit error probability than regular $\pi$/4- DQPSK by simulation. The former achieves much smaller average bit error probability than the latter for small TEX>${\tau}/T_{s}$.

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