基于EMF的MRAS无速度传感器矢量控制系统研究

转速辨识是无速度传感器矢量控制系统的关键,转速估计的精度将直接影响矢量控制系统的控制效果。将模型参考自适应(MRAS)方法用于异步电机矢量控制系统中,提出了一种利用电机反电动势(EMF)构造转速辨识模型的方法,该方法不含有纯积分环节,能够有效避免积分初始误差和直流偏移问题,较好地辨识电机转速。最后利用MATLAB/SIMULINK软件对系统进了行建模和仿真研究,结果表明,此控制系统具有较好的辨识精度和静、动态性能。     

基于无速度传感器异步电机的风力机模拟研究

风力机模拟系统使在实验室内开展风力发电技术的各项研究成为可能。分析了风力机特性,建立了风力机模型。通过对异步电机间接磁场定向矢量控制技术的研究,考虑到安装速度传感器具有诸多缺陷,提出基于模型参考自适应（MRAS）转速辨识理论的无速度传感器异步电机的风力机模拟控制方法,并且考虑到转子时间常数对矢量控制系统的影响,采用同时辨识电机转速和转子时间常数,使系统辨识转速同时,对电机参数变化具有较强的鲁棒性。利用MATLAB/SIMULINK搭建了基于无速度传感器异步电机的风力机模拟系统,通过对风力机特性,最大风能捕获和电机参数对矢量控制系统影响的仿真,证明了系统的可行性。     

基于模型参考分数阶自适应转速估计的永磁同步电机控制研究

针对模型参考整数阶自适应转速估计存在稳态误差较大、转速估计精度低的问题,结合无传感器技术和分数阶理论的优点,在空间矢量脉宽调制技术的基础上,对永磁同步电机提出了一种模型参考分数阶自适应转速估计方案。仿真实验表明所提速度调节策略和辨识方案可使矢量控制系统具有良好的动、静态性能,对比整数阶控制,分数阶控制下电机转速跟踪精度提高、范围扩大,电机在转速、转矩和电流等方面的控制性能得到提高,改善了永磁同步电机伺服系统的快速性、鲁棒性、稳定性及抗负载突变能力。     

基于MRAS的无速度传感器的异步电机矢量控制

研究基于模型参考自适应系统(MRAS)的无速度传感器的异步电机矢量控制系统。首先介绍了矢量控制技术,接着介绍了基于MRAS的转速自适应估计理论,运用该理论构成了无速度传感器异步电机矢量控制系统;又利用Matlab对无速度传感器的异步电机矢量控制系统系统进行了建模仿真;仿真结果表明采用的控制策略控制效果良好,能在较大负载扰动下实现无传感器方式的异步电机的稳定运行。     

矿井提升机的无速度传感器矢量控制

针对矿井提升机对高性能调速的需要,对矢量控制技术进行了详细地研究,建立了基于模型参考自适应系统(MRAS)的无速度传感器异步电机矢量控制系统,实现了转速的在线辨识;又利用Matlab/Simulink对控制系统进行了建模仿真;仿真结果表明采用的控制策略控制效果良好,能在较大负载扰动下实现无传感器方式的异步电机的稳定运行.     

基于MRAS的永磁同步电机无速度传感器控制研究

研究了一种模型参考自适应系统(model reference adaptive system,MRAS)方案,用于永磁同步电机(permanent magnet synchronous motor,PMSM)无速度传感器矢量控制系统的转速辨识。以PMSM为参考模型,电机的电流模型为可调模型。设计了自适应律PI调节器参数,达到了可调模型能稳定跟踪参考模型的目的,实现了PMSM无速度传感器矢量控制系统的转速和位置估算。仿真结果表明,所提出的转速辨识方法在高低速均能准确检测到转子的速度和位置,系统具有较好的鲁棒性和良好的动静态运行性能。     

基于EKF的无轴承异步电机无速度传感器控制

为解决无接触、无摩擦无轴承异步电机低成本运行中转速辨识问题,提出了一种基于扩展卡尔曼滤波器的无速度传感器控制方法。该方法分别将电机的端电压和定子电流作为无轴承异步电机状态方程的控制变量和可测变量,并将系统状态方程降阶后,经扩展卡尔曼滤波器估计的递推公式得出含有电机转子转速的状态变量,实现转速参量的在线辨识并减少计算量。仿真结果表明:利用该检测方法构造的控制系统不仅能在宽速范围内有效观测转子转速,且具有优良的转速和转矩特性。进一步实验也表明,该控制方法能准确辨识出转速,并将转子径向位移峰-峰值控制在100μm以内稳定悬浮运行,实现了无轴承异步电机无速度传感器方式下的稳定悬浮运行,验证了所提检测方法的正确性与有效性。     

基于简化MRAS的永磁同步电机无传感器矢量控制

推导了采用id=0的矢量控制策略下,永磁同步电机采用简化的模型参考自适应系统(MRAS)对转子速度估计的算法,并对该算法进行了仿真,仿真结果表明此方法可以精确地估计转速和转子位置。     

基于简化MRAS的永磁同步电机无传感器矢量控制

推导了采用id=0的矢量控制策略下,永磁同步电机采用简化的模型参考自适应系统（MRAS）对转子速度估计的算法,并对该算法进行了仿真,仿真结果表明此方法可以精确地估计转速和转子位置。     

基于模型参考神经网络自适应异步电机无速度传感器矢量控制系统的研究

针对在传统的异步电机矢量控制系统中采用编码器、光电码盘等速度传感器来对转速进行检测给系统带来的一些缺陷,该文将模型参考方法和神经网络相结合,提出了一种模型参考BP神经网络的无速度传感器异步电机矢量控制方案,并设计了速度辨识环节.同时对系统进行了仿真和实验,结果表明:该方法具有较强的抗干扰能力,受电机参数影响小,能较好地估计电机转子的转速.     

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...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

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.     

Fifth International Summer School on Screw-Theory Based Methods in Robotics

正3-11 September,2014University of Bologna,Bologna,Italy www.summerscrews.org summerscrews2014.ing.unibo.it SUMMER 20SCREWS 14In 2014,our screw-theory school comes to the world's oldest university.In early September,Summer Screws'14 will gather six experts in the application of screw theory in robotics and up to 40 participants at the University of Bologna,Bologna,Italy.The school will teach attendees how to apply existing methods and empower them to develop new ones in their own research.The basic theoretical notions will be introduced in a rigorous manner,emphasizing examples,applications,and exercises.Scholarships are available.     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

INDUSTRIAL ENGINEERING AND VISUALISATION-A PRODUCT DEVELOPMENT PERSPECTIVE

Taking the actual project of teaching and researching process for example, the relationship between the industrial engineering and product development is discussed. And use the novel visualization technology to support the industrial engineering and product development. How to use the new computer modeling and simulating technologies to support the product development and industrial engineering, is introduced especially. The support includes both domestic products and industrial systems. The visualization and computer technologies take a very important role in some system or multi-direction modeling, those technologies mentioned above can help the industrial engineers study the effect of design on the whole life circle, including the producing steps. So the engineers can avoid making the wrong decision which may cause bad effects on the whole industrial engineering.     

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.