采用双自由度PI速度控制器的PMSM矢量控制仿真研究

分析了永磁同步电机的数学模型.采用励磁电流id=0的转子磁场定向矢量控制方法,在Matlab/Simykuink环境下构建了永磁同步电机(PMSM)矢量控制仿真模型.针对常规PI控制无法满足当电机转速和负载转矩发生阶跃变化时,电机动态响应曲线中转速超调量小和转速恢复施加短的要求,提出了一种双自由度PI速度控制方法.仿真...     

基于重复控制的位置伺服系统

提出了一种控制交流伺服系统的新方法。在永磁同步电机矢量控制的基础上,利用重复控制策略对位置伺服系统进行了控制。根据重复控制理论设计重复控制器,使系统响应输出跟踪周期性输入的参考信号,从而达到跟踪控制的目的。介绍了重复控制的原理、算法以及永磁同步电机数学模型的建立,并给出了重复控制器设计的思路。最后,在输入为周期性位置给定的前提下,进行了仿真实验。仿真结果表明,整个控制系统设计简单、可行、有效。     

基于LPV观测器的永磁同步电机反推控制

针对永磁同步电机(Permanent Magnet Synchronous Motor,PMSM)无速度传感器转速跟踪控制精度问题,提出了一种基于线性变参数(Lineeo Parameteo Varying,LPV)转速观测器的永磁同步电机反推控制方法。该方法首先根据PMSM的LPV模型,推导出电机的凸胞形顶点方程;然后利用Lyapunov稳定性理论,获得了基于线性矩阵不等式(Lineeo Matrix Inequality,LMI)的观测器设计方法,构造了PMSM的LPV观测器,实现对电机转速及定子交轴电流的重构;最后运用反推控制策略,设计电机闭环系统控制器,实现对电机转速的高精度跟踪控制。仿真结果表明,该方法相较与传统PI矢量控制,跟踪精度高、响应快、抗负载扰动强,对实现PMSM的无速度传感器高精度转速跟踪控制具有重要意义。     

异步电机矢量控制系统的设计及仿真研究

研究异步电机控制系统优化问题,系统要求稳定性和抗干扰性能。传统的矢量控制中速度调节器和电流调节器采用PI调节器,依据PI调节器特性,在控制过程中速度响应会出现超调。为了解决上述问题,提出了一种异步电机矢量控制中速度调节器的设计方法,以抑止异步电机矢量控制中速度响应的超调和增强抗扰性为目的。异步电机矢量控制采用转子磁场定向实现解耦,并采用速度环、电流环双环控制方法,根据内模控制原理,设计用一种速度调节器,取代常规的PI调节,成功解决了转速的超调和负载扰动对电机转速的影响。仿真结果表明,提高了响应特性,为优化设计提供了参考。     

异步电机模糊调速矢量控制系统仿真研究

依据异步电机矢量控制原理,空间电压矢量脉宽调制理论（SVPWM）以及模糊控制原理,在Matlab/Simulink下建立了异步电机矢量控制的仿真模型。仿真结果表明,采用该系统对三相异步电机进行控制,具有转矩波动小,转速响应快,超调量小等特点,运行性能良好。     

基于EKF和SMC的永磁同步电机无传感器矢量控制

采用扩展卡尔曼滤波(EKF)算法估计永磁同步电机(PMSM)转速和转子位置,构成转速、电流双闭环的无传感器矢量控制系统.针对扩展卡尔曼滤波为有偏估计、对模型误差鲁棒性差等问题,提出了基于指数趋近律的滑模转速控制器.为提高转速环抗负载转矩扰动能力,设计负载转矩观测器并将观测结果引入到电流控制器的输入端,作为速度控制器前馈补偿的控制输入.仿真实验结果表明,与传统采用PI(proportional-integral)转速控制器的系统相比,文中所提控制策略具有转速跟踪误差小、响应快、无超调、抗负载扰动能力强等优点.     

基于模糊控制的直流无刷伺服控制系统

主要研究采用模糊算法设计全数字化微机控制直流无刷伺服系统. 分析了模糊控制器在伺服系统中稳态误差、调节时间和响应时间方面的性能. 用Matlab语言仿真了模糊控制的响应, 并且提出了PI控制加模糊控制的算法, 采用DSP数字信号处理器实现伺服控制.     

智能观测器在伺服系统控制中的应用

研究优化伺服控制系统策略,永磁同步电动机( PMSM)的伺服系统优化,可改善电动机系统的稳定性和响应特性.通过提高伺服系统定位精度和抗干扰能力,有效保证机器运行效率.针对传统有速度传感器矢量控制增加了系统复杂度和成本的问题,为优化伺服系统控制结构,提出了一种采用神经网络观测器的伺服系统无速度传感器矢量控制策略.系统中不需要安装传感器来检测PMSM转子位置/速度信号,而是利用神经网络观测器从电机反电动势信号中估算转子位置/速度,从而优化了系统整体结构,减小了系统复杂度.通过对PMSM的伺服系统无速度传感器矢量控制系统的建模与仿真测试,结果表明,所设计的神经网络观测器能够准确估算转子位置/速度,控制系统能够精确跟踪给定转速指令,改进了伺服系统优化控制问题,为实际应用提供了参考.     

SiC器件在高速永磁电机转速跟踪控制中的应用研究北大核心CSCD

针对高速永磁同步电机(HSPMSM)的电感值小、基波频率高等特点,以及Si基IGBT开关速度和电压等级限制而引起的电机运行过程中定子电流谐波含量高、发热严重和响应延迟大的问题,研究SiC金属氧化物半导体场效应晶体管(MOSFET)在HSPMSM转速跟踪控制中的应用。通过双脉冲测试电路分析了SiC和Si器件的开关特性,结果表明SiC MOSFET具有更快的开关速度和更低的开关损耗。基于Simulink/PSpice联合仿真,搭建了HSPMSM矢量控制仿真模型。仿真结果表明,采用SiC器件的逆变器能加快电机转速响应速度,减少电流高次谐波,提高输出稳定性,从而提高转速跟踪性能。     

永磁同步电机的高阶终端滑模控制方法

提出一种基于高阶终端滑模的永磁同步电机转速控制方法, 提高了系统的鲁棒性和响应速度. 根据矢量控制原理, 设计了非奇异终端滑模面, 使得电机转速、直轴电流、交轴电流在有限时间内达到给定值. 同时, 采用高阶滑模消除抖振, 保证系统的稳定性. 仿真结果表明, 和PI控制方法相比, 电机转速能够更快地跟踪给定值, 并且, 系统对于负载扰动具有较强的鲁棒性.     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.