基于滑模和扩张状态观测器的双绕组无轴承磁通 切换电机转子悬浮控制策略研究

双绕组无轴承磁通切换电机是非线性多变量的复杂对象,传统的转速PI与径向位移PI控制存在超调大,系统易受外界扰动影响等缺点。基于滑模变结构控制思想,提出一种转子径向位移滑模控制策略。针对滑模控制中存在建模不准确,以及转子动力学模型中存在陀螺效应等问题,通过建立一种扩张状态观测器对系统扰动进行观测,并在滑模控制基础上加入扰动前馈补偿,设计出一种径向位移滑模控制与扩张状态观测器的复合控制策略。实验结果表明,所提径向位移滑模控制相比传统PI控制具有响应速度快、径向位移脉动小、抗负载扰动性强等优点。所提径向位移滑模与扩张状态观测器的复合控制策略,相比于径向位移滑模控制可有效减小转子径向位移脉动约30%,进一步增强了系统的鲁棒性。     

双馈异步风力发电机匝间短路故障研究分析

双馈异步风力发电机是我国目前应用最为广泛的发电机,其结构主要由转子、定子、轴承三部分组成。转子的组成部分在运转的过程中,主要通过电流之间产生的磁势,而进行正常运行的。在风力发电机中转子在工作中出现匝间短路的现象,就说明了定子中的分支电流的电压是不相同的,从而会引起双馈式风力发电机的电流出现不平衡的现象,通过对双馈异步风力发电机建立多回路模型,这就可以根据时间的变化计算出双馈异步风力发电机所需要的电气量。     

变速恒频风力发电机组控制策略研究

分析了双馈风力发电机组(DFIG)的数学模型及系统的控制策略.转子侧变换器采用定子磁链定向控制策略,以实现定子绕组有功功率和无功功率的解耦控制;网侧变换器采用电压定向直接功率控制,可稳定直流母线电压并实现网侧功率因数可调的目的.     

永磁型电主轴多频率振动的主动控制

为了有效抑制由砂轮质量不平衡及外部干扰引起的永磁型电主轴转子系统砂轮端的多频率成分振动,在无轴承永磁电机径向磁悬浮力产生原理的基础上,提出了一种基于最小方差快捷分块(FBLMS)的自适应滤波的永磁型双绕组电主轴柔性转子系统砂轮端多频率成分振动的主动控制方案。首先研究了双绕组永磁型电主轴结构及工作原理和径向控制力的模型,借助有限元法建立了永磁型电主轴柔性转子系统的动力学模型,分析了控制电流的不同成分对永磁体涡流损耗及电机定子铁损的影响,设计了永磁型电主轴柔性转子系统砂轮端多频率成分振动的主动控制系统,结果表明,提出的永磁型电主轴柔性转子系统砂轮端多频率成分振动控制方案具有明显的控制效果。     

基于扩张状态观测器的海工栈桥液压系统模型预测控制

海工栈桥是一种在海上作业期间运输维护人员和设备转移的大型海洋工程装备。针对海工栈桥液压系统外部扰动大、模型参数不确定等问题,提出了一种基于扩张状态观测器的模型预测控制方法。以海工栈桥液压系统为研究对象,对其进行运动学分析和动力学建模,推导出系统的状态空间方程;在传统模型预测控制的基础上,采用扩张状态观测器对液压系统的外部负载扰动以及机械系统未建模部分进行估计,以提高模型预测控制的跟踪效果。仿真结果表明,扩张状态观测器对海工栈桥液压系统的状态和扰动具有很好的观测能力,有效提高了模型预测控制的稳定性和鲁棒性。     

基于线性自抗扰控制器和磁通观测器的异步电机调速系统

针对异步电机难以建立精确的数学模型和采用PI调节器的矢量控制系统参数鲁棒性差的问题,将线性自抗扰控制器引入异步电机调速系统中.线性自抗扰控制器不需要电机的精确数学模型,通过线性扩张状态观测器估计出电机模型中的耦合项及参数摄动等引起的总扰动并加以补偿,实现了磁链和转矩的完全解耦.针对磁通观测器对转子电阻的鲁棒性差的问题,文中引入一个建立在旋转坐标系中的磁通观测器,结构简单,对转子电阻具有固有的鲁棒性.在观测磁通的基础上,根据矢量控制理论,采用a轴磁通收敛于零估计转速,从而建立了无速度传感器矢量控制异步电机调速系统.仿真结果表明此控制方案具有很好的动、静态性能,且对负载扰动、电机参数变化等具有很强的鲁棒性.     

基于滑模观测器的磁轴承转子不平衡扰动控制

针对风力发电机磁轴承转子不平衡扰动的问题,建立了系统动力学模型。基于滑模变结构理论,设计了滑模扰动观测器,对磁轴承转子系统扰动量进行观测,将观测器的输出作为补偿信号引入磁轴承转子系统,对系统的不平衡扰动力和力矩进行补偿。仿真结果表明,设计的滑模变结构扰动观测器能够准确快速地观测不平衡扰动,通过补偿减少了转子不平衡扰动。     

不平衡及谐波电网条件下双馈风电变流器的改进控制研究

针对双馈风电机组在电网电压不平衡及谐波畸变条件下的故障穿越问题,分析了此类电网故障对机组运行性能的影响,提出了一种双馈机组转子侧、网侧变流器的协同控制方案。通过改进转子侧、网侧变流器的矢量控制算法,抑制了双馈感应电机的电磁转矩波动,降低了机组输出总有功功率的波动,获得了对称、正弦的机组输出电流。仿真结果表明,所述控制方案能够显著改善双馈风电机组在此类电网故障条件下的运行性能,从而提高机组的故障穿越运行能力。     

基于双ESO无电流传感器的永磁同步电机 驱动系统磁场定向控制

针对无任何相电流传感器的三相永磁同步电机(PMSM)驱动系统,提出了一种新颖的基于双扩张状态观测器(ESO)无电流传感器的磁场定向控制(FOC)策略。一般需要两个相电流传感器以进行电流反馈实现高精度控制,为此创建了两个ESO来替代实际电流传感器。第一个ESO用于提供q轴定子电流基准值;考虑到定子电阻和电感变化,第二个ESO用于估计实时d轴和q轴定子电流。所创建的双ESO能够快速和精确地估计实际定子三相电流,所设计的基于双ESO无电流传感器的FOC策略能够使PMSM驱动系统具有良好的控制性能和较强的鲁棒性。仿真实验验证了所提方法的可行性和有效性。     

基于滑模扰动观测器的磁轴承主动振动控制

由于磁悬浮控制力矩陀螺转子的不平衡振动会造成控制力矩陀螺系统的同频扰动,影响卫星姿态控制精度与卫星载荷精度,本文提出了基于滑模变结构扰动观测器的磁轴承主动振动控制方法.首先,对不平衡扰动力和力矩作用下的磁轴承-转子系统进行建模;接着,设计了滑模变结构扰动观测器观测不平衡扰动力和力矩;然后,利用跟踪微分器估计位移传感器输出信号的微分获取速度信号,降低观测器的阶数;最后,将滑模扰动观测器的输出引入磁轴承控制器,对观测得到的同频不平衡扰动力和力矩进行补偿.仿真和试验结果均表明,设计的滑模变结构观测器实现了对不平衡扰动的观测,通过控制器有效地实现了对不平衡扰动的补偿,减少了72％的同频振动.     

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。     

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.     

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.