直接转矩控制系统定子电阻观测的研究

目前直接转矩控制系统是控制感应电动机的一种新兴技术,它不需要复杂的控制算法就可以得到异步电动机的磁链和转矩．但是感应电动机定子电阻的变化影响直接转矩控制系统的低速性能,因此调节电动机的定子电阻是非常重要的．本文综述了直接转矩控制系统定子电阻观测方法的研究现状,阐述了定子电阻不同的观测方法,并展望了直接转矩控制技术的应用前景．     

计及结构特征的TEFC感应电动机温度敏感性研究

为研究小型感应电动机温升分布与其结构特性的数值关系,以一台TEFC(Total enclosed fan-cooled)感应电动机为研究对象,根据流体力学和传热学基本理论,并结合感应电动机定子绕组散下线等结构特点,建立包含离心式风扇及接线盒等结构部件的三维流动与传热耦合数学模型及物理模型,采用有限体积元法,对其三维流体场及温度场进行耦合计算,在利用试验数据佐证本研究精准性的基础上,详细地阐明电动机内部温升随结构特性的敏感性,结果表明,机壳底脚上的横向拉筋对电动机内部的温升分布有着较大的影响,导致与其位置对应的定子绕组存在温升二次升高的现象,同时,转子上具有自力性的风扇对定子绕组端部表现出良好的散热效果,以上结论为中小型电动机的机械结构优化提供了一定参考。     

双馈异步感应发电机动态模型的研究与仿真

随着风力发电在电网中所占的比例越来越高,其对电网的影响也变得日益显著。为了维护电网的稳定性,对风力发电机组在电网发生故障时提出"低电压穿越"的能力要求。为了分析风力发电机组在暂态过程中的变化过程,需要构建双馈异步感应发电机的动态模型。双馈异步感应发电机在机构上与三相感应异步电动机相似。因此,在三相异步感应电动机原理的基础上适当修改进行双馈异步感应发电机动态模型的建立和仿真。而matlab中没有详细的双馈反应风力发电机的模型。因此,需要自行搭建。     

电动机使用维修常识

三相异步电动机又叫感应电动机,它是一种结构简单、坚固耐用、使用和维护方便、运行可靠的电动机,主要由定子和转子组成。在绝大多数起重设备、运输机械上都得到了广泛应用。     

九相感应电动机的矢量控制研究

以九相感应电动机的动态数学模型为基础,对九相感应电动机调速系统的矢量控制进行了研究。通过坐标变换,得到九相感应电动机在两相同步旋转d-q坐标系下的矢量控制方程。将定子电流分解成转矩分量和励磁分量,通过对这两个分量进行调节,可实现转子磁链和电磁转矩的控制。按转子磁链定向矢量控制的基本思想设计调节器,并在Simulink软件平台中搭建九相感应电动机的矢量控制模型进行仿真分析。结果表明,九相感应电动机的矢量控制系统具有较好的稳态和动态性能。     

专利

专利名称：双直线同步电动机驱动的精密重型机床磁悬浮运动平台 专利申请号：CN201020614007.X公开号：CN201881156U 申请日：2010.11.19公开日： 2011.06.29申请人：沈阳工业大学 本实用新型提供一种双直线同步电动机驱动的精密重型机床磁悬浮运动平台,包括运动平台和两个长定子直线同步电动机及其控制系统。直线同步电动机主要包括定子铁心和可以与定子铁心做相对运动的动子铁心。     

全封闭扇冷式感应电动机通风结构方案

为了揭示全封闭扇冷式（Total enclosed fan-cooled,TEFC）感应电动机底脚拉筋结构对电动机流场流变特性以及温升分布性能的影响,近而寻求拉筋结构最优化通风冷却性能,以一台TEFC感应电动机为例,在对该电动机进行温升试验测试及温度场数值分析研究的基础上,依据结构特征建立电动机轴向半域流体场以及温度场耦合求解模型,采用有限体积元法对多种拉筋结构方案下的电动机内流体场及温度场进行数值计算。通过对各方案下电动机定子铁心、定子绕组、机壳等部件温升特征以及电动机域内流变特性的比较分析,明确了电动机机壳拉筋对电动机内流体场以及温度场的影响规律,给出了机壳拉筋结构优化方案。     

定子频率自控式同步电动机的发展与现状

无换向器电动机、永磁无刷电动机、开关型磁阻电动机、双凸极电动机和磁通切换式永磁电动机本质上均为频率闭环控制的同步电动机,故可同归类于定子频率自控式同步电动机。综述了定子频率自控式同步电动机的主要类型、特点及研究现状,对其发展进行了展望。     

转子槽参数对开槽实芯转子永磁电机的影响研究

针对小功率感应电动机效率较低、功率因数不高等问题,对已有的三相感应电动机改造为一种新型同步电机-开槽实心转子自起动永磁同步电动机进行了研究。对Y90L-4,1.5 k W型感应电动机进行了分析,利用其定子,重新设计一新型转子。所设计的转子采用实芯结构,沿转子铁芯外圆周开槽,且铁芯内置永磁极。利用有限元计算并分析了转子槽参数对电机自起动能力和稳态运行性能的影响,归纳出了其中的规律性。最后对比了感应电动机和基于改进的开槽实心转子自起动永磁同步电动机的起动和稳态运行性能。研究结果表明:开槽实心转子自起动永磁同步电动机的起动转矩倍数更大,不同负载转矩下的功率因数更高。     

内置电动机定子外套加工工艺改进分析

内置电动机定子外套是弹簧双端面磨床的一个关键零件。磨头内置电动机带动主轴和磨轮旋转,完成磨削动作,同时由进给电动机通过滚珠丝杠传动带动整个磨头部分上下移动,完成磨削进给。定子外套不仅起着电动机外壳的防护作用,还在主轴孔里往复移动,因此定子外套加工质量的高低与整个产品的使用性能紧密相连,定子外套的重要性不可忽视。下面将此零件的加工工艺及其加工刀具的改进设计过程进行论述。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.