基于多阶滑模的永磁无刷直流电动机干扰抑制研究

本文使用MATLAB/Simulink软件仿真无转轴传感器无刷直流电机驱动系统,以线对线反电动势得到换相点信号,经过滑模控制器控制转速与电流,三相变频器输出电压到无刷直流电机,最后得到无刷直流电机转速、电压、电流、角位置等信息。实验结果验证了本文提出的控制方案能有效抑制瞬间负载干扰,使转速能在短时间恢复稳态值。     

无刷直流电机自适应模糊控制系统建模与仿真

建立无刷直流电机（BLDCM）数学模型,并利用Matlab／Simulink中的无刷直流电机模块搭建了仿真模型,实现了电流环、转速环和位置模糊自适应控制环的三闭环位置伺服系统的仿真。分析了无刷直流电机系统的动、静态性能,得到了电机运行时的位置和转速响应、相电流和相电动势的仿真波形曲线。仿真结果表明位置控制器采用模糊白适应控制算法,响应快,位置、转速响应无超调,具有较强的自适应和鲁棒性。该模型准确易实现,便于修改和替换,仿真结果为BLDCM控制系统的实现提供参考。     

无刷直流电机模糊自适应PID的研究及仿真

为了实现负载变化情况下转速的快速跟踪控制,采用模糊 PI控制器,改变传统 PI控制器的固定参数的控制策略,采用根据跟踪误差信号来实时控制参数的方法。无刷直流电机建模过程中,给出了较理想的反电动势波形是一直难解决的问题,采用分段线性法编写S-函数,通过MATLAB建立无刷直流电机速度环和电流环的双环控制系统仿真模型,其中速度环采用模糊 PI控制,分析了无刷直流电机的动、静态性能,得到了理想的相电流、反电动势以及扭矩的波形图。仿真结果表明相对于常规 PI控制,采用模糊自适应PI控制器实现负载变化情况下转速的快速跟踪控制,提高了系统的抗干扰能力,提高了系统的响应速度。     

节能空调用无刷直流电机的无位置传感器控制方法

介绍了节能空调用无刷直流电机的原理及数学模型,提出了基于符号检测的反电动势过零点检测方法,设计了基于dsPIC的无位置传感器控制系统,并给出了节能空调用无刷直流电机控制系统软、硬件结构及实现方法。     

基于电流匹配反电势的无刷直流电机节能策略

无刷直流电机具有传统直流电机所不具备的诸多优点,比如说取消电刷,大大增加了工作寿命与可靠性,功率密度大等,同时直流无刷电机也具备传统直流电机所具备的大部分优点,调速性能好、效率高、控制简单等,这些原因使得直流无刷电机广泛应用在工业控制和日常生活中。电机作为能源消耗主力,在倡导节能减排、绿色环保的今天,对其进行节能研究成为热点。现通过对无刷直流电机工作原理及数学模型进行分析,设计了一种基于电流匹配反电势的无刷直流电机节能策略,根据不包含零序谐波的反电动势得到最优电流波形,以提高电机输出功率,从而达到节能的目的。同时,通过Matlab/Simulink平台对提出的控制策略进行了仿真验证。     

基于LS052A-Cb的无刷直流电机的控制系统设计

基于设计一款高效节能的无刷直流电机的控制系统方案的目的,LS052A-Cb是一款国产通用型单片机,能够实现多核多任务并行处理。在研究了SVPWM基本原理的基础上,采用空间矢量脉宽调制技术的方法,通过运用反电动势检测实现无位置传感器方式的位置检测,并检测速度和电流采集运用双闭环PID的控制策略实现了对无刷直流电机的速度控制的试验,得出一种新型无刷直流电机控制系统的方案可行,具有应用价值。     

无刷直流电机模糊PID控制及建模仿真

基于对无刷直流电机(BLDCM)工作原理及数学模型进行的简要分析,在MATLAB软件的Simulink模块中,通过S-Function函数和Simulink独立集成模块,搭建出无刷直流电机控制系统仿真模型,对无刷直流电机控制系统进行速度环、电流环双闭环控制,使电机在仿真环境中能够正常运行.仿真控制系统采用模糊控制算法优化PID控制参数,仿真结果与理论分析基本吻合,验证了无刷直流电机模糊PID控制算法具有响应快、超调小等良好的控制性能.     

无位置传感器无刷直流电机控制器的设计

无刷直流电机具有结构简单、重量轻、体积小、安全可靠性和运行效率高等特点,被广泛应用于各种工业设备中。针对航空用无刷直流电机起动困难的问题,以LPC2148控制器为核心,设计了一种无位置传感器无刷直流电机控制器。采用反电动势过零检测法、三段式起动、双闭环控制、软件补偿相位延迟等控制策略,设计了控制器的硬件电路和软件程序,很好解决了无位置传感器无刷直流电机的起动问题。最后搭建仿真模型和实验平台,验证了所设计控制器的实用性和可靠性。     

基于SVPWM控制的无刷直流电机的建模与仿真

针对传统无刷直流电机（BLDCM）控制系统方波驱动转矩脉冲大等缺点,采用了基于电压空间矢量脉宽调制（SVPWM）控制方法的正弦波驱动永磁无刷直流电机控制系统,建立了两级三相无刷直流电机的数学模型,利用Matlab／Simulink中的电力系统仿真T具箱SimPow—erSystems建立了SVPWM控制下的无刷直流电机转速、电流双闭环控制系统的仿真模型。仿真结果表明,电压空间矢量控制下的无刷直流电机控制系统具有较好的静、动态特l生,同时该仿真结果也验证了SVPWM控制无届Ⅱ直流电机的有效性和仿真模型的正确性。     

无位置传感器直流无刷电动机自整定模糊控制系统研究

本文在分析无位置传感器直流无刷电动机的反电动势换相原理的基础上,建立了利用反电动势换相的数学模型.针对反电动势换相起动困难的问题,采用"三段式"起动技术,即转子预定位、外同步加速和外同步到自同步的切换,达到与有位置传感器相同的起动效果;控制方法采用自整定模糊-PID控制.系统采用双闭环调速,其中电流环采用滞环控制,转速环采用自整定模糊-PID控制器.研究结果表明:基于自整定模糊-PID控制器的无位置传感器直流无刷电动机控制系统具有同有位置传感器直流无刷电动机控制系统同样好的控制效果,且超调小,较传统PID控制具有更好的静、动态特性.     

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...     

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.     

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.     

Fractional order nonsingular terminal sliding mode control for flexible spacecraft attitude tracking

This paper investigates a fractional terminal sliding mode control for flexible spacecraft attitude tracking in the presence of inertia uncertainties and extern...     

奥氏体不锈钢表面双辉等离子渗锆的动力学

利用双辉等离子渗金属技术在0Cr18Ni9Ti奥氏体不锈钢表面制备了一层均匀、致密、呈良好冶金结合的渗锆合金层,并对1 060℃下的渗锆动力学进行了研究。结果表明:随着距锆合金层表面距离的增加,锆元素的含量呈梯度递减,扩散系数逐渐减小,而扩散激活能逐步增大;在1 060℃采用双辉等离子技术渗锆时,渗锆合金层表层的空位密度为2.945×(1012~1013)cm-2,与相同温度下采用常规渗金属工艺相比,提高了1~2个数量级。     

气化炉三维扫描测量与数据处理

以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可.