基于无速度传感器直接转矩控制自抗扰交流调速研究

在感应电机直接转矩控制(DYC)调速系统中,常规PID速度调节器在电机受到扰动的情况下,需要花费较长时间才能使电机恢复到稳态值.为此,将一种新型的自抗扰控制器(ADRC)引入感应电机直接转矩控制调速系统中,设计速度ADRc调节器代替PID调节器,基于模型参考自适应控制(MRAS)方法设计速度观测器.对比分析了PID与ADRC两种方案下无速度传感器直接转矩控制交流调速系统性能.仿真试验结果表明,采用ADRC后,系统动态响应更快,抗扰动能力更强,在电机参数摄动的情况下,电机运行速度与指令速度偏差更小.     

基于89C51单片机控制的包装机自动纠偏系统

针对包装机在纠偏控制中存在的问题,开发了基于89C51单片机的控制系统.通过对枕式包装机工作原理的分析,详细介绍了该系统的硬件和软件设计. 系统采用步进电机直接驱动横封装置,使枕式包装机在高速生产过程中,实现精确定位.     

电机防护包装系统设计

分析了电机包装在运输、装卸和储存过程中存在的各种流通环境,介绍了电机防护包装技术和方法.根据电机包装的流通环境和防护要求,建立电机防护包装系统,通过计算机辅助设计实现其系统的防水,防潮、防锈及运输包装设计的智能化,为电机防护包装系统设计提供方法.     

基于改进的三段式永磁同步电机启动方法

永磁同步电机(Permanent magnet synchronous motor,PMSM)使用位置传感器会增加控制系统的体积和成本,降低系统的稳定性和可靠性,使得PMSM控制系统使用场合受限.而传统的无位置传感器启动方法都是开环启动,这种方式没有准确可靠的位置信息,缺乏动态性能,容易出现启动电流过大、电机反转等问题.本文在分析了相关启动过程的基础上,针对这些问题提出了基于电流幅值变斜率递减的改进的3段式控制方法,实现启动过程平滑,状态切换过程无冲击.实验结果表明:该启动方法使得PMSM能够在带载情况下,实现电机的零速平稳启动,切换过程平滑,控制性能良好.     

VAV空调系统中风机运行方案对比研究

分析了VAV空调系统中风机在恒速电机结合风档、变速电机结合风档以及变频调速电机等三种不同运行控制下如何根据工况的变化进行调节,并比较了各种运行方案的经济性,指出了影响经济性的因素.     

AT89C51单片机在SR电机控制中的应用小议

随着单片机在电机控制领域中出现的越来越频繁，其对电机的发展和完善起着越来越重要的作用。我们针对其在SR电机控制中的应用进行了系统的探究和阐述。     

直驱式螺杆泵无刷直流电机的模糊自适应PID控制

针对传统螺杆泵驱动的弊端,提出采用直接驱动螺杆泵的方式省去电机和光轩之间的传动机构,提高传动效率.但在省去中间传动机构后.光杆上所受到的各种扰动无缓冲的作用在电机轴上.为了克服传统PID控制器在采油系统中存在的缺点,在控制系统中引入模糊自适应PID控制以增强系统的鲁棒性.仿真结果表明.模糊自适应PID控制方法在这种非线性、时变的采油系统中.具有更强的鲁棒性.     

异步驱动电机扭矩波动对电动汽车纵向冲击影响的仿真研究

对电动汽车异步驱动电机在转子磁场定向矢量控制中因电机参数变化导致磁场解耦不完全,致使电机输出扭矩波动和扭矩及速度跟踪可能失效,进而带来纵向冲击和影响乘坐舒适性的问题进行了研究和分析,并在此基础上进行了电机控制策略的仿真分析.基于多体系统动力学建立了整车纵向动力学模型,并与控制系统一起建立了耦合仿真模型.利用所建立的耦合模型进行了电动汽车美国联邦循环工况(UDC)的仿真计算,计算结果表明所提出的矢量控制方法是可行的,能够有效改善电动汽车的纵向冲击问题.     

基于随动测量系统的步进电机跟踪精度研究

利用ARM控制系统实现齿轮测量仪的两轴随动控制,完成齿轮螺旋线高精度测量.根据步进电机脉冲信号和步距角的线性关系,采用ARM系统输出频率脉冲控制步进电机,由于步进电机只有周期误差而无累积误差,系统能够实现齿轮螺旋线偏差快速、准确测量.与现有系统比较,本系统具有控制精度高、测量速度快、误差精度高的特点,能够实时、动态显示测量误差.     

单片机在电机控制中的应用效果探析

在电机控制过程中,为了提高电机控制效果,并使电机能够按照预定的目标运转,单片机的运用成为了必然选择。从目前单片机的运用来看,单片机是电机控制系统中的核心部件,对电机控制效果有着重要影响。基于单片机的自身特点及其对电机控制的影响,深入探讨单片机在电机控制中的应用及效果是十分必要的。为此,我们应立足单片机的应用实际,重点探讨单片机在电机控制中的应用效果,为单片机的应用提供有力支持,保证单片机在电机控制中取得积极效果。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。