• Title, Summary, Keyword: phase error

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A Feasible Approach for the Unified PID Position Controller Including Zero-Phase Error Tracking Performance for Direct Drive Rotation Motor

  • Kim, Joohn-Sheok
    • Journal of Power Electronics
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    • v.9 no.1
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    • pp.74-84
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    • 2009
  • The design and implementation of a high performance PID (Proportional Integral & Differential) style controller with zero-phase error tracking property is considered in this article. Unlike a ball screw driven system, the controller in a direct drive system should provide a high level of tracking performance while avoiding the problems due to the absence of the gear system. The stiff mechanical element in a direct drive system allows high precise positioning capability, but relatively high tracking ability with minimal position error is required. In this work, a feasible position controller named 'Unified PID controller' is presented. It will be shown that the function of the closed position loop can be designed into unity gain system in continuous time domain to provide minimal position error. The focus of this work is in two areas. First, easy gain tunable PID position controller without speed control loop is designed in order to construct feasible high performance drive system. Second, a simple but powerful zero phase error tracking strategy using the pre-designed function of the main control loop is presented for minimal tracking error in all operating conditions. Experimental results with a s-curve based position pattern commonly used in industrial field demonstrate the feasibility and effective performance of the approach.

Location Error Analysis of an Active RFID-Based RTLS in Multipath and AWGN Environments

  • Myong, Seung-Il;Mo, Sang-Hyun;Yang, Hoe-Sung;Cha, Jong-Sub;Lee, Heyung-Sub;Seo, Dong-Sun
    • ETRI Journal
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    • v.33 no.4
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    • pp.528-536
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    • 2011
  • In this paper, we analyze the location accuracy of real-time locating systems (RTLSs) in multipath environments in which the RTLSs comply with the ISO/IEC 24730-2 international standard. To analyze the location error of RTLS in multipath environments, we consider a direct path and indirect path, in which time and phase are delayed, and also white Gaussian noise is added. The location error depends strongly on both the noise level and phase difference under a low signal-to-noise ratio (SNR) regime, but only on the noise level under a high SNR regime. The phase difference effect can be minimized by matching it to the time delay difference at a ratio of 180 degrees per 1 chip time delay (Tc). At a relatively high SNR of 10 dB, a location error of less than 3 m is expected at any phase and time delay value of an indirect signal. At a low SNR regime, the location error range increases to 8.1 m at a 0.5 Tc, and to 7.3 m at a 1.5 Tc. However, if the correlation energy is accumulated for an 8-bit period, the location error can be reduced to 3.9 m and 2.5 m, respectively.

Phase Offset Enumeration Method with Error Detection and Its Application to Synchronization of PN Sequences

  • Song Young-Joan
    • Journal of electromagnetic engineering and science
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    • v.5 no.1
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    • pp.26-30
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    • 2005
  • It is important to know phase offsets of PN(Pseudo Noise) sequences in spread spectrum communications since the acquisition is equivalent to making a phase offset between a receiving PN sequence and a PN sequence of local PN generator be identical. In this paper, a phase offset enumeration method for PN sequences with error detection, and its application to the synchronization are proposed. The phase offset enumeration for an n-tuple PN sequence and its error detection are performed when one period of the sequence is received. Once the phase offset of the receiving sequence is calculated, we can easily accomplish the synchronization by initializing shift registers of a local PN generator according to the phase offset value. The mean acquisition time performance of the proposed scheme was derived analytically. Since this synchronization scheme can be realized by using simple circuit and acquires very rapid acquisition in high SNR but shows performance degradation in low SNR, it can be especially useful in indoor and office environments.

Evaluation Technique of Burden for Current Transformer using Current Transformer Comparator and Precise Shunt Resistor (전류변성기 비교기와 정밀션트저항을 이용한 전류변성기용 부담의 평가기술)

  • Lee, Sang-Hwa;Kang, Jeon-Hong;Kim, Myung-Soo;Jung, Jae-Kap
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.55 no.5
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    • pp.250-256
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    • 2006
  • Both ratio error and phase angle error in current transformer(CT) depend critically on values of CT burden. Thus, precise measurement of CT burden is very important for the evaluation of CT. A method for the measurement of CT burden has been developed by employing the portable shunt precise resistor with negligible AC-DC resistance difference less than $10^{-5}$. The burden value(value and power factor) can be calculated from resistance and reactance obtained by measuring the change of ratio error and phase angle error caused by the change of shunt resistor. The uncertainty for the method is evaluated and found to be abut 2 %.

On-Site Calibration Technology of Burden using Voltage Transformer Comparator (전압변성기 비교기를 이용한 부담의 현장교정 기술)

  • Jung, Jae Kap;Kwon, Sung Won;Park, Young Tae;Kim, Myung Soo
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.54 no.11
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    • pp.503-507
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    • 2005
  • Both ratio error and phase angle error in voltage transformer(VT) depend on values of VT burden used. Thus, precise measurement of burden is very important for the evaluation of VT. A method of evaluation for VT burden has been developed by employing the portable decade resistor, with AC-DC resistance difference less than 10-3. The burden value(value and power factor) can be obtained by conductance and susceptance, obtained by measuring the change of ratio error and phase angle error caused by the resistance change of decade resistor. The burden value and power factor obtained by the method are consistent with those obtained using power analyzer within corresponding uncertainties.

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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Torque Sharing Function of SRM for Torque Ripple Reduction in Commutation Region (커뮤테이션 구간의 토크리플 저감을 위한 SRM의 토크 분배 함수 기법)

  • Kim, Tae-Hyoung;Wang, Huijun;Lee, Dong-Hee;Ahn, Jin-Woo
    • Proceedings of the KIPE Conference
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    • pp.148-150
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    • 2007
  • A novel 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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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.

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.

ERROR ESTIMATES FOR A SINGLE-PHASE NONLINEAR STEFAN PROBLEM IN ONE SPACE DIMENSION

  • Lee, H.Y.;Ohm, M.R.;Shin, J.Y.
    • Journal of the Korean Mathematical Society
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    • v.34 no.3
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    • pp.661-672
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    • 1997
  • In this paper we introduce the semidiscrete solution of a single-phase nonlinear Stefan problem We analyze the optimal convergence of the semidiscrete solution in $H^1$ and $H^2$ normed spaces and also we derive the error estimates in $L^2$ normed space.

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