三相异步电机建模与动态协同仿真技术实现

Matlab在复杂参数元件的仿真模型方面存在不足,不能直观、准确地给出电机在复杂电磁环境下的实际工况。针对这一问题,对ANSYS的三相异步电机建模与协同仿真技术进行研究。为了实现三相异步电机的动态协同仿真,对整个机电系统的性能进行分析,采用Ansys/Maxwell仿真软件建立三相异步电机本体模型、Ansys/Simplorer软件建立控制系统主电路、Matlab/Simulink建立电机控制策略的仿真模型。将电机本体有限元模型和控制系统模型相结合。重点对电机控制系统的匹配性能、电磁性能、机械特性以及稳定性进行精确分析,进而给出电机建模与仿真建模方法、步骤以及分析结果。通过仿真研究发现,动态联合仿真不仅能够真实地反映变频调速系统的实际运行情况,而且能够直观地展示电机在调速过程的电磁分布以及磁场变化。这对于变频调速控制系统的理论研究具有重要的现实意义。     

改电磁调速为变频调速的方法

1.方法 将电磁调速改为变频调速有两种方法。 （1）拆除原电磁调速电机和调速控制器,重新选择、购置异步电机和变频调速器。这样投资成本大,改造工作量大。     

基于BP神经网络的电机转矩软测量研究

本文将在化工领域广泛使用的软测量技术应用来进行异步电机转矩测量。根据感应电动机的数学模型，提出了仅用葶于神经网络的电机定子电流的电磁转矩辨识方法，实现异步电机转矩的软测量。用改进的BP算法对神经网络进行学习和训练，构建了适合电机转矩观测的多层前馈神经网络，仿真研究表明：基于神经网络的电机转矩辨识模型具有良好的性能。     

基于无源控制的无速度传感器异步电机调速控制

建立其交流异步电机的欧拉—拉格朗日数学模型,再以无源控制理论实现电机调速控制。为了转速反馈的准确性,加入了转速估算环节。充分利用被控系统已有的结构,直接比较给定的电磁转矩和估算的电磁转矩,运用PI闭环控制构造出转速信号。在Simulink中搭建仿真模型进行实验,仿真结果表明：此控制方法对交流异步电机速度控制具有较好的静/动态性能和抗干扰性。     

励磁电流对TMPS-HESM振动噪声影响的仿真分析

为了研究励磁电流对切向聚磁型并联结构混合励磁电机(TMPS-HESM)振动噪声的影响,根据TMPS-HESM切向聚磁特点,建立电机等效磁路模型和Maxwell有限元仿真模型,在不同励磁电流条件下仿真分析了与电机振动噪声有关的转矩脉动、气隙磁密和电磁力等电磁性能。利用ANSYS Workbench仿真平台搭建了电磁振动噪声耦合仿真模型,计算了不同励磁电流条件下电机的振动响应与噪声变化。结果表明：励磁电流对混合励磁电机转矩脉动影响较小,对电机径向电磁力谐波(8,2f₁)、(16,4f₁)、(0,12f₁)分量影响较大,是造成电机振动噪声的主要原因,其中(0,12f₁)分量虽然与其它分量不是一个数量级,但仍会恶化电机振动噪声。     

基于遗传粒子群的永磁低速直线电机优化研究

本文以改善电机效率和降低永磁低速直线电机制造成本为优化设计目标,把单台电机造价和电机电磁推力的比值作为目标函数,由于目标函数的优化变量多,参数间相互约束,目标函数复杂等特点,因此本文采用遗传粒子群算法对永磁低速直线电机进行优化设计,通过对两种设计仿真结果对比证明了该算法在提高电机电磁性能,降低制造成本方面有明显的优越性。     

空调用永磁无刷直流电机磁场分析与损耗计算

传统空调电机一般采用单相异步电动机,这种单相异步电动机存在效率低、噪音大、功率密度小等缺点,因此,空调电机中性能优越的永磁无刷直流电机将逐渐取代异步电机。利用Ansoft软件建立了空调用永磁无刷直流电机二维瞬态场有限元模型,对铁芯磁场进行分析,并对负载损耗进行计算。软件计算值和实验值的比对误差较小,为空调用永磁无刷直流电机实际产品设计提供了理论依据。     

基于TMS320F2812的异步电机变频调速系统设计与应用

针对空压机中大功率异步电机费电问题,为实现节能需对电机变频凋速。文中介绍了用于电机控制的芯片的最新发展状况,讨论了基于TMS320F2812的异步电机变频调速系统在空压机控制中的硬件设计,介绍了各部分硬件电路的实现。通过电压空间矢量方法实现了对异步电机的变频控制。实践表明,该系统有较高的灵活性和稳定性,适合于复杂的无传感器矢量控制和直接转矩控制算法的实现。     

考虑铁损时异步电机的仿真

推导出在转子磁场定向控制中两相同步旋转坐标系下不考虑铁损和考虑铁损的三相异步电机动态数学模型,进而建立基于Simulink的不考虑铁损和考虑铁损的三相异步电机仿真模型.用仿真实例比对两个模型,验证了考虑铁损的异步电机模型在磁场定向时能更真实地反映电机实际物理过程,为异步电机的控制问题提供了一个更加接近电机行为特性的高效仿真模型.     

基于TMS320F2812的异步电机变频调速系统设计与应用

针对空压机中大功率异步电机费电问题,为实现节能需对电机变频调速.文中介绍了用于电机控制的芯片的最新发展状况,讨论了基于TMS320F2812的异步电机变频调速系统在空压机控制中的硬件设计,介绍了各部分硬件电路的实现.通过电压空间矢量方法实现了对异步电机的变频控制.实践表明,该系统有较高的灵活性和稳定性,适合于复杂的无传感器矢量控制和直接转矩控制算法的实现.     

Effective solution of certain problems of theory of schedulings of nets

Cybernetics and Systems Analysis -     

Complexity of families of learning algorithms and estimation of the nonrandomness of extraction of empirical regularities

The paper presents a general approach to the evaluation of the complexity of classes of algorithms, so-called pVCD-method. To develop this method, all the examined families of models of empiric generalization were restricted to classes implementable on computers and, wider, by examining their partially recursive representations. Within the framework of the algorithmic approach, the concept of Kolmogorov’ complexity of algorithms for the recognition of properties or the extraction of regularities is proposed. The method proposed to evaluate the nonrandomness of the extraction of empirical regularities is based on this concept.     

Analysis of microdensitometric data in terms of probability of cleavage of DNA

Computer-aided analysis of autoradiographic films of DNA fragments is presented. The Powell least-squares procedure is used for optimization of parameters for components of complex densitometric curves. Since each densitometric spectrum may be divided for several non-overlapped blocks of bands, there is no upper limit on the number of parameters which must be optimized. Eight shapes for the component bands are utilized: symmetric and asymmetric Gauss and Cauchy functions, direct, symmetric and asymmetric product of Gauss function and inverse of Cauchy function, and log-normal function. The probability of DNA cleavage is calculated with correction for multiple cuts. The methods presented was applied to detailed analysis of densitometric spectra of a 21-bp DNA restriction fragment and allowed for direct correlation between structural microheterogeneity of DNA and the resulting cutting pattern. This method should facilitate the analysis of densitometric data from antibiotic-induced cleavage of DNA and footprinting experiments.     

联合收割机脱粒滚筒恒速智能控制器设计

研究了轴流式联合收割机的控制问题,给出了联合收割机脱粒滚筒的数学模型,介绍了基于模式识别的智能控制原理,建立了联合收割机脱粒滚筒恒速控制模型,设计了基于模式识别的智能恒速控制器.应用Matlab/Simulink进行了控制器仿真,其结果表明,将基于模式识别的智能控制应用于联合收割机脱粒滚筒的恒速控制,其过渡过程平稳、响应速度快、无超调、无振荡并且无稳态误差.     

An estimate of numbers of terms of semicycles of delay difference equations

In this paper, we study the semicycles of oscillatory solutions of the delay difference equation y_n+1 − y_n + p_ny_n-k = 0, where p_n is a sequence of nonnegative real numbers and k is a positive integer. Upper bound of numbers of terms of semicycles are determined in the case when

Our results improve and complement known results in literature.     

Complexity of approximation of 3-edge-coloring of graphs

The problem to find a 4-edge-coloring of a 3-regular graph is solvable in polynomial time but an analogous problem for 3-edge-coloring is NP-hard. To make the gap more precise, we study complexity of approximation algorithms for invariants measuring how far is a 3-regular graph from having a 3-edge-coloring. We show that it is an NP-hard problem to approximate such invariants with an error O(n1−ε), where n denotes the order of the graph and 0<ε<1 is a constant.     

Modifications of the method of variation of parameters

In spite of being a classical method for solving differential equations, the method of variation of parameters continues having a great interest in theoretical and practical applications, as in astrodynamics. In this paper we analyse this method providing some modifications and generalised theoretical results. Finally, we present an application to the determination of the ephemeris of an artificial satellite, showing the benefits of the method of variation of parameters for this kind of problems.     

计算机辅助课表编排技术的研究

讨论了几种实用的计算机辅助课表编排技术及在实际编排中的应用。应用分析表明，采用分批与或图搜索和分批优化的匈牙利算法相结合的方法，在计算机辅助课表编排中是行之有效的。