• Title/Summary/Keyword: Q-compensation

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A New Dead-time Compensation Method using Disturbance Observer (외란관측기를 이용한 새로운 데드타임 보상법)

  • 김현수;문형태;김명복;윤명중
    • Proceedings of the KIPE Conference
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    • 1999.07a
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    • pp.252-255
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    • 1999
  • A new dead-time compensation method using a disturbance observer is proposed. The dead-time causes the voltage distortion and it can be considered as the disturbance voltage. In this paper, the disturbance voltage is estimated by minimal order observer in the d-q frame and the estimated disturbance voltage is summed with voltage command by a feed-forward. The experiments are carried out for the DSP-based BLDC motor drive system and the results show the effectiveness of the proposed method.

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A Syudy On DVR Control for Unbalanced Voltage Compensation (불평형 전압 보상을 위한 DVR 제어에 관한 연구)

  • Jung, Hong-Ju;Chung, Joon-Mo;Song, Jong-Whan
    • Proceedings of the KIEE Conference
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    • 2001.04a
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    • pp.218-221
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    • 2001
  • This paper presents a new control scheme for a Dynamic Voltage Restorer(DVR) system consisting of series voltage source PWM converters. The control system is designed using differential controllers and digital filters to transfer the faulted ac source voltage to a d-q model and to separate the positive and negative sequence component for individual compensation. The performance of the presented controller and scheme are confirmed through simulation and actual experiment.

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Improvement of PLL Method for Voltage Control of Dynamic Voltage Restorer (동적전압보상기의 전압제어를 위한 PLL 방식의 개선)

  • Kim, Byong-Seob;Choi, Jong-Woo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.5
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    • pp.936-943
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    • 2009
  • Dynamic voltage restorer(DVR) is now more preferable enhancement than other power quality enhancement in industry to reduce the impact of voltage faults, especially voltage sags to sensitive loads. The main controllers for DVR consists of PLL(phase locked loop), compensation voltage calculator and voltage compensator. PLL detects the voltage faults and phase. Compensation voltage calculator calculates the reference voltage from the source voltage and phase. With calculated compensation voltage from PLL, voltage compensator restores the source voltage. If PLL detect ideal phase, compensation voltage calculator calculates ideal compensation voltage. Therefore, PLL for DVR is very important. This paper proposes the new method of PLL in DVR. First, the power circuit of DVR system is analyzed in order to compensate the voltage sags. Based on the analysis, new PLL for improving transient response of DVR is proposed. The proposed method uses band rejection filter(BRF) at q-axis in synchronous flame. In order to calculate compensation voltage in commercial instruments, the PQR theory is used. Proposed PLL method is demonstrated through simulation using Matlab-Simulink and experiment, and by checking load voltage, confirms operation of the DVR

A Novel Method for Rejection of the Spurious Signal in Weaver-Type Up-Conversion Mixer (위버구조 상향변환 혼합기의 스퓨리어스 신호 제거 방법)

  • 김영완;송윤정;김유신;이창석
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.15 no.7
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    • pp.661-668
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    • 2004
  • A novel method to reject the spurious signals which are occurred at Weaver-type low-IF transmitter was proposed in this paper. The spurious signals are generated by the gain and phase imbalances of I/Q channel or imperfect characteristics of 90$^{\circ}$ phase shifter in local oscillator for I/Q channel source. By deriving the gain and phase-based functions from RF spurious signal with the channel imbalance information, the lie channel imbalances were deduced as functions with magnitude and sign dependent on I/Q channel imbalance degree. The proposed method compensates the estimated I/Q channel imbalances by correlation values between the down-converted signal obtained by squaring the output signal itself using a simple mixer and the modified baseband signal. By comparing two signals after A/D conversion, the magnitude and sign of each type of imbalances can be determined separately and simultaneously. Based on the I/Q channel imbalance compensation, the spurious signals can be reduced by adjusting the gain and phase values of I or Q channel signal. The way to estimate the channel imbalances of the up-conversion mixer was presented and verified by using theoretical derivations and computer simulations.

Phase Offset Correction using Early-Late Phase Compensation in Direct Conversion Receiver (직접 변환 수신기에서 Early-Late 위상 보상기를 사용한 위상 오차 보정)

  • Kim Young-Wan
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.9 no.3
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    • pp.638-646
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    • 2005
  • In recent wireless communications, direct conversion transceiver or If sampling SDR-based receivers have being designed as an alternative to conventional transceiver topologies. In direct conversion receiver a.chitectu.e, the 1.equency/phase offset between the RF input signal and the local oscillator signal is a major impairment factor even though the conventional AFC/APC compensates the service deterioration due to the offset. To rover the limited tracking range of the conventional method and effectively aid compensation scheme in terms of I/Q channel imbalances, the frequency/phase offset compensation in RF-front end signal stage is proposed in this paper. In RF-front end, the varying phase offset besides the fixed large frequency/phase offset are corrected by using early-late phase compensator. A more simple frequency and phase tacking function in digital signal processing stage of direct conversion receiver is effectively available by an ingenious frequency/phase offset tracking method in RF front-end stage.

Three-Phase Z-Source Dynamic Voltage Restorer with a Fuel Cells Source (연료전지 전원을 갖는 3상 Z-소스 동적 전압 보상기)

  • Jung, Young-Gook
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.22 no.10
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    • pp.41-48
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    • 2008
  • This paper proposes a three-phase Z-source dynamic voltage restorer (Z-DVR) to mitigate the voltage sag for the critical loads. The proposed system is composed of passive filter and Z-source topology inverter. As an ESS(Energy Storage System) of the proposed system is employed the Proton Exchange Membrane Fuel Cells (PEMFC). To calculate and control the harmonics and compensation voltage, $i_{d}-i_{q}$ theory in dq rotating reference frame and PI controller are used. In case that three-phase voltage sags occurred, a PSIM simulation was done for the performance comparison of the conventional method employed battery stacks and proposed method. As a result, considering the voltage compensation performance, each method was nearly similar. Also, the compensation performance and the %THD(%Total Harmonic Distortion) result under the various source voltage conditions (sag or swell) were presented and discussed to show the performance of the proposed system.

Design of Disturbance Observer Based on Structural Analysis (구조적 분석에 기초한 외란관측기의 설계)

  • 김봉근
    • Journal of Institute of Control, Robotics and Systems
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    • v.10 no.3
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    • pp.225-231
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    • 2004
  • Disturbance observer (DOB) has been studied extensively and applied to many motion control fields during the last decades, but relatively few studies have been devoted to the development of analytic, systematic design methods for DOB itself, This paper thus aims to provide an analytic, systematic design method for DOB. To do this, DOB is structurally analyzed and the generalized disturbance compensation framework named robust internal-loop compensator (RIC) is introduced. Through this, the inherent equivalence between DOB and RIC is found, and the mixed sensitivity optimization problem of DOB is solved. Q-filter design is completely separated from the mixed sensitivity optimization problems of DOB although the proposed method has implicit .elation with Q-filter. Also, although the Q-fille. is separately designed with sensitivity function, the proposed DOB framework has the exactly same characteristic as the original DOB.

A Study on the Subjectivity of Perceived Work Values in Nurses (간호사가 인식하는 근로 가치에 관한 주관성 연구)

  • Han, Hye-Sook
    • Journal of Korean Academy of Nursing Administration
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    • v.15 no.4
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    • pp.506-514
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    • 2009
  • Purpose: Nowadays nursing is facing a constantly increasing shortage of employees. While there are many causes for the present nursing shortage, a major contributing factor is the revolution in fundamental values what we expect in life. An understanding of the change can assist in identifying interventions that can be used to address this crisis in healthcare. The purpose of this study is to identify the features they look for in work and the underlying factors of the work values domain. Methods: Using Q methodology, 37 nurses rated 34 selected Q-statements on a scale of 1-9. The collected data were analyzed using pc-QUNAL software. Results: The results showed that work values, which nurses indicate as most important through working, were perceived as 4 factors; 'compensation oriented', 'security oriented', 'professional role oriented' and 'freedom oriented' work value. Conclusion: Providing for these findings will result in greater job satisfaction among nurses, better nurse retention and enhanced patient care within a supportive and harmonious organization.

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Radial Basis Function Neural Networks (RBFNN) and p-q Power Theory Based Harmonic Identification in Converter Waveforms

  • Almaita, Eyad K.;Asumadu, Johnson A.
    • Journal of Power Electronics
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    • v.11 no.6
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    • pp.922-930
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    • 2011
  • In this paper, two radial basis function neural networks (RBFNNs) are used to dynamically identify harmonics content in converter waveforms based on the p-q (real power-imaginary power) theory. The converter waveforms are analyzed and the types of harmonic content are identified over a wide operating range. Constant power and sinusoidal current compensation strategies are investigated in this paper. The RBFNN filtering training algorithm is based on a systematic and computationally efficient training method called the hybrid learning method. In this new methodology, the RBFNN is combined with the p-q theory to extract the harmonics content in converter waveforms. The small size and the robustness of the resulting network models reflect the effectiveness of the algorithm. The analysis is verified using MATLAB simulations.

Q-factor Improvements of WDM Signals using Optical Transmission Link with Dispersion Management and OPC (분산 제어와 OPC를 갖는 광전송 링크를 이용한 WDM 신호의 Q-factor 개선)

  • Lee, Seong-Real
    • Journal of Advanced Navigation Technology
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    • v.13 no.1
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    • pp.27-33
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    • 2009
  • New optical transmission link techniques improving performance of WDM channels, each channel have bit rate of 40 Gbps, are proposed. The proposed optical link configuration consist of optical phase conjugator (OPC) placed at middle of total transmission length, and dispersion management (DM) as a role of compensating dispersion cumulated in transmission line. It is confirmed that Q-factor of total channels are improved by combining OPC and DM in optical transmission link as a result of following fact; DM not only mitigate the cumulated dispersion in total transmission line but also help OPC to compensate optical nonlinearities. And, it is confirmed that the improvement of Q-factor of overall WDM channels depends on net residual dispersion (NRD) of optical link.

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