The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform

Ziyuan Li - One of the best experts on this subject based on the ideXlab platform.

  • LS-SVM Inverse System Decoupling Control Strategy of a Bearingless Induction Motor Considering Stator Current Dynamics
    IEEE Access, 2019
    Co-Authors: Wenshao Bu, Ziyuan Li
    Abstract:

    The bearingless induction motor (BL-IM) is a multivariable, nonlinear and strongly coupled object, in order to achieve its dynamic decoupling control with high performance, on the basis of the least square support vector machine(LS-SVM) principle, a novel LS-SVM inverse system decoupling control strategy is proposed. Firstly, under the conditions of taking the stator current dynamics of torque windings into account, the state equations of the BL-IM system are established. Secondly, based on the approximation and identification fitting ability of the LS-SVM to arbitrary nonlinear function, the inverse system mathematical model of the BL-IM system considering the stator current dynamics is trained and obtained. After that, according to the decoupling principle of inverse system, the BL-IM system is decoupled into four second-order pseudo-linear integral subsystems, include a motor speed subsystem, a rotor flux-linkage subsystem and two radial Displacement Component subsystems. At the end, the comprehensive simulation analysis of the LS-SVM inverse decoupling control system are carried out. From the simulation results, it can be known that the dynamic decoupling control among the motor speed, rotor flux-linkage and two radial Displacement Components can be realized, meanwhile after considering the dynamics of the stator current, the LS-SVM inverse decoupling control system of BL-IM has the characteristics of fast response and strong anti-interference ability.

  • Unbalanced vibration control strategy of bearingless induction motor based on inverse system decoupling
    International Journal of Applied Electromagnetics and Mechanics, 2016
    Co-Authors: Wenshao Bu, Fangzhou He, Chunxiao Lu, Ziyuan Li, Juanya Xiao
    Abstract:

    Bearingless induction motor is a multi variable, nonlinear and strong coupling object, in order to achieve its sus- pension control with high performance, the dynamic model of magnetic suspension system is established; and the radial dis- placement of bearingless rotor is separated into two parts, include random Displacement Component and unbalanced vibration Displacement Component. Then by inverse system method, dynamic decoupling control between the two random Displacement Components is achieved. On this basis, through the compensation controller of unbalanced vibration, the compensation force of unbalanced vibration is regulated and estimated real time, and the control current of unbalanced vibration compensation force is calculated. The compensation force is used to counteract the unbalanced exciting force of bearingless rotor. Under the dq coordinate system oriented by the rotor flux-linkage of torque system, the control current compensation of unbalanced vibra- tion is achieved. At the end, simulation verification and analysis are made. From the simulation results, it is clear that when the proposed control strategy is adopted, the unbalanced vibration of bearingless rotor can be inhibited effectively in the start stage; the unbalanced vibration Displacement can be eliminated in steady state. The proposed control strategy is effective and feasible.

Parul Garg - One of the best experts on this subject based on the ideXlab platform.

  • VTC-Fall - Cross-QAM Signaling in Free Space Optical Communication Systems with Generalized Pointing Errors
    2017 IEEE 86th Vehicular Technology Conference (VTC-Fall), 2017
    Co-Authors: Nikhil Sharma, Parul Garg
    Abstract:

    We analyse the performance of cross quadrature amplitude modulation (X-QAM) scheme in subcarrier intensity modulation (SIM) based free space optical (FSO) communication system under the influence of atmospheric turbulence and generalized pointing error. The QAM signalling is the preferred modulation scheme for multimedia transmission over wireless channels due to its high bandwidth efficiency. The FSO links are vulnerable to atmospheric fading and misalignment errors. Most of the previous works model the random radial Displacement Component of pointing error by Rayleigh distributed random variable. However, for a non-ideally fasttracked laser beam, the radial Displacement Component may not obey the Rayleigh distribution, since the Displacements in vertical and horizontal directions may not always follow a zeromean Gaussian distribution. In this work, we derive the closed form expression of the probability density function (PDF) for the aggregated channel with atmospheric turbulence modeled by gamma-gamma distribution and the pointing error modeled by Rician distributed radial Displacement Component. Further, we derive the closed form expressions of the exact average symbol error rate (ASER) for general order cross QAM.

  • Cross-QAM Signaling in Free Space Optical Communication Systems with Generalized Pointing Errors
    2017 IEEE 86th Vehicular Technology Conference (VTC-Fall), 2017
    Co-Authors: Nikhil Sharma, Parul Garg
    Abstract:

    We analyse the performance of cross quadrature amplitude modulation (X-QAM) scheme in subcarrier intensity modulation (SIM) based free space optical (FSO) communication system under the influence of atmospheric turbulence and generalized pointing error. The QAM signalling is the preferred modulation scheme for multimedia transmission over wireless channels due to its high bandwidth efficiency. The FSO links are vulnerable to atmospheric fading and misalignment errors. Most of the previous works model the random radial Displacement Component of pointing error by Rayleigh distributed random variable. However, for a non-ideally fasttracked laser beam, the radial Displacement Component may not obey the Rayleigh distribution, since the Displacements in vertical and horizontal directions may not always follow a zeromean Gaussian distribution. In this work, we derive the closed form expression of the probability density function (PDF) for the aggregated channel with atmospheric turbulence modeled by gamma-gamma distribution and the pointing error modeled by Rician distributed radial Displacement Component. Further, we derive the closed form expressions of the exact average symbol error rate (ASER) for general order cross QAM.

H.l. Yadav - One of the best experts on this subject based on the ideXlab platform.

  • Design and analysis of modified version of double aperture speckle interferometer consisting of holographic optical element: Application to measurement of in plane Displacement Component
    Optik, 2015
    Co-Authors: R.k. Jayaswal, H.l. Yadav, P.k. Barhai
    Abstract:

    Abstract Duffy's double aperture speckle interferometer consists of two apertures placed symmetrically over an imaging lens and is used to measure in plane Displacement Component parallel to the line joining the two apertures using speckle photography. Diffraction limited imaging performance almost free from all monochromatic aberration over the two apertures is desirable for accurate measurement. In present work twin apertures are placed over a compact holographic lens (hololens) system. Lens system consists of two properly recorded and played back holographic lenses cemented together with proper alignment. Recording and play back geometry of holographic lenses has been designed for ease of alignment similar that of an on-axis imaging performance obtained by a conventional lens. Experimental results on measurement of in plane Displacement along a line joining the two apertures using the designed interferometer is presented and compared with the actual Displacement given to a diffuser between the two exposures. Further, results on measurement of in-plane Displacement by analyzing speckle correlation fringes contained in zero order and ±1st order are presented to show that measurement made by analyzing fringes contained in ±1st order give better result than that of results obtained by analyzing speckle correlation fringes contained in zero order. In plane Displacement measurement carried out by measuring fringe width of young's fringes contained in ±1st order provides an experimental technique to avoid cumbersome mathematical calculation for correction in the measured value of fringe spacing as suggested by several researchers.

  • Fabrication of double-aperture hololens imaging system: Application to mechanics
    Optics and Lasers in Engineering, 2004
    Co-Authors: H.l. Yadav, Anshuman Mallick, Neelam Kumari, Ravi Bhushan, B N Gupta
    Abstract:

    Duffy suggested the use of double-aperture imaging system for the measurement of in-plane Displacement Component. In this arrangement, twin apertures are placed symmetrically over the imaging lens. This imaging system is used in speckle metrology to measure Component of Displacement parallel to the line joining the two apertures. The imaging lens used in such configuration need not be diffraction limited over the entire lens aperture, but only over the two small areas encompassed by the two apertures. In present work, compact holographic lenses have been used to generate the two apertures of Duffy's double-aperture interferometer. This imaging system has been used in speckle metrology to measure crack mouth opening Displacement (CMOD) in an aluminium beam specimen having central edge crack subjected to three point bending. Experimental results are in good agreement with theoretical predictions. Present experimental investigation reveals that compact holographic lenses can be used advantageously to generate apertures of double-aperture speckle interferometer for its use in the measurement of in-plane Displacement Component. © 2003 Elsevier Ltd. All rights reserved.

Giuseppe Pezzo - One of the best experts on this subject based on the ideXlab platform.

  • measuring the north south coseismic Displacement Component with high resolution multi aperture insar
    Terra Nova, 2015
    Co-Authors: John Peter Merryman Boncori, Giuseppe Pezzo
    Abstract:

    Earthquake source inversions based on space-borne Synthetic Aperture Radar interferometry (InSAR) are used extensively. Typically, however, only the line-of-sight (LoS) surface Displacement Component is measured, which is mainly sensitive to the vertical and E–W deformations, although well-established methods also exist to estimate the flight-path Component, which is highly sensitive to the N–S Displacement. With high-resolution sensors, these techniques are particularly appealing, because accuracies in the order of 3 cm can be achieved, while retaining spatial resolutions between 45 m and a few km, depending on the required level of filtering. We discuss the application to COSMO-SkyMed SAR imagery of the Spectral Diversity or Multi Aperture Interferometry technique, presenting the first SAR flight-path Displacement field associated with the Mw 6.3, 2009 L'Aquila event (central Apennines). Finally, we observe and characterize a previously unknown misregistration pattern.

Wenshao Bu - One of the best experts on this subject based on the ideXlab platform.

  • LS-SVM Inverse System Decoupling Control Strategy of a Bearingless Induction Motor Considering Stator Current Dynamics
    IEEE Access, 2019
    Co-Authors: Wenshao Bu, Ziyuan Li
    Abstract:

    The bearingless induction motor (BL-IM) is a multivariable, nonlinear and strongly coupled object, in order to achieve its dynamic decoupling control with high performance, on the basis of the least square support vector machine(LS-SVM) principle, a novel LS-SVM inverse system decoupling control strategy is proposed. Firstly, under the conditions of taking the stator current dynamics of torque windings into account, the state equations of the BL-IM system are established. Secondly, based on the approximation and identification fitting ability of the LS-SVM to arbitrary nonlinear function, the inverse system mathematical model of the BL-IM system considering the stator current dynamics is trained and obtained. After that, according to the decoupling principle of inverse system, the BL-IM system is decoupled into four second-order pseudo-linear integral subsystems, include a motor speed subsystem, a rotor flux-linkage subsystem and two radial Displacement Component subsystems. At the end, the comprehensive simulation analysis of the LS-SVM inverse decoupling control system are carried out. From the simulation results, it can be known that the dynamic decoupling control among the motor speed, rotor flux-linkage and two radial Displacement Components can be realized, meanwhile after considering the dynamics of the stator current, the LS-SVM inverse decoupling control system of BL-IM has the characteristics of fast response and strong anti-interference ability.

  • Unbalanced vibration control strategy of bearingless induction motor based on inverse system decoupling
    International Journal of Applied Electromagnetics and Mechanics, 2016
    Co-Authors: Wenshao Bu, Fangzhou He, Chunxiao Lu, Ziyuan Li, Juanya Xiao
    Abstract:

    Bearingless induction motor is a multi variable, nonlinear and strong coupling object, in order to achieve its sus- pension control with high performance, the dynamic model of magnetic suspension system is established; and the radial dis- placement of bearingless rotor is separated into two parts, include random Displacement Component and unbalanced vibration Displacement Component. Then by inverse system method, dynamic decoupling control between the two random Displacement Components is achieved. On this basis, through the compensation controller of unbalanced vibration, the compensation force of unbalanced vibration is regulated and estimated real time, and the control current of unbalanced vibration compensation force is calculated. The compensation force is used to counteract the unbalanced exciting force of bearingless rotor. Under the dq coordinate system oriented by the rotor flux-linkage of torque system, the control current compensation of unbalanced vibra- tion is achieved. At the end, simulation verification and analysis are made. From the simulation results, it is clear that when the proposed control strategy is adopted, the unbalanced vibration of bearingless rotor can be inhibited effectively in the start stage; the unbalanced vibration Displacement can be eliminated in steady state. The proposed control strategy is effective and feasible.