交流电机调速系统中矢量控制技术的FPGA实现

在常见的电机控制系统中,空间矢量脉宽调制SVPWM是一种驱动电机旋转的高效脉冲调制方法。现介绍了矢量控制原理及其坐标变换,在此基础上构建了双闭环调速系统;同时介绍了SVPWM模块的FPGA生成方法,并对SVPWM模块在QuartusⅡ中进行了验证。该方案结合了SVPWM与FPGA的优点,在高性能运动控制系统中有重要的应用价值。     

基于FPGA的异步电动机变频调速系统

针对传统的单片机(MCU)或数字信号处理器(DSP)以软件方式实现的控制系统普遍存在速度慢、稳定性差等问题,以实现全数字电机控制器的集成化为背景,提出了一种基于现场可编程门阵列(FPGA)的空间电压矢量脉宽调制(SVPWM)硬件设计方案,并结合EDA模块化的设计方法和Verilog HDL硬件描述语言,在一片FPGA芯片中得到了验证和实现;采用"top-down"设计思想,对系统按功能划分模块进行了设计;首先对各功能模块进行了设计、仿真、验证,然后将整个系统组合起来进行了仿真、验证,最后利用FPGA进行了硬件验证;在此基础上,完成了异步电机SVPWM调制方式的V/F开环变频调速系统的实验。研究结果表明,该系统稳定性高、占用资源少、复用性高,在实时性、灵活性等方面有着MCU、DSP无法比拟的优越性,为设计高性能的电机控制专用芯片奠定了基础。     

基于DSP和FPGA的三电平逆变器快速控制方法

在传统的三电平电压型逆变器空间矢量脉宽调制(SVPWM)控制算法基础上.结合"DSP FPGA",实现了一种快速的空间矢量调制算法,详细阐述了基于FPGA和DSP的硬件平台实现方法,实现了资源的最大化利用,提高了逆变器控制的快速性,为并网实验控制提供了更多资源.最后,通过仿真和实验结果对比验证了这一调制算法的可行性.     

基于FPGA的永磁同步电机伺服控制系统设计

为了研究与实现高性能的永磁同步电机(PMSM)伺服控制系统,设计了基于FPGA的伺服控制方案.在PMSM的数学模型基础上,根据矢量控制理论,采用现代EDA设计方法和模块化设计思想,在单片FPGA上实现了电机矢量控制系统的坐标变换、空间矢量脉宽调制(SVPWM)、三闭环控制调节器、电机反馈接口以及上位机通信模块.系统同时兼容增量式编码器和多摩川绝对式编码器,电流环频率达25 kHz,位置环和速度环频率达12.5 kHz,具有高可靠性、可拓展、响应快的优点.实验验证了系统的可行性,并且具有较好的位置精度和动态性能.     

基于FPGA的两相步进电机细分驱动器设计

采用步进电机驱动的机构中,为了提高定位精度,文章提出了一种高性能的步进电机细分控制系统设计,该系统由FPGA和专用集成电路IXMS150 PSI构成,在FPGA中嵌入Cos/Sin表,通过查表控制步进电机两项绕组电流,实现了高精度的步进电机细分控制系统,提高了步进电机的运行精度,消除了低速震荡现象,该系统可用于机器人,打印机和光学平台等精密位置控制系统。     

基于DSP与人工神经网络技术的交流电机控制器的设计

介绍了一种基于DSP与人工神经网络技术的交流电机控制器.根据SVPWM的基本原理,利用人工神经网络技术,提出了一种新型的SVPWM计算方法.通过MATLAB的离线建模与学习、DSP的实时控制,设计了一款高性能的交流电机矢量调速控制器,实现了对交流电机运行的有效控制.     

基于FPGA的光栅位移检测系统设计

本文介绍了用可编程器件FPGA对光栅传感器采集来的数字信号进行处理和控制的方法.利用光栅传感器把位移转换成电压脉冲的特点,同时利用在线可编程阵列FPGA高集成度、高性能、高效率和低成本的优点设计了一种用于机床位移测量与控制的数字系统,并阐述了该系统位移检测原理、总体方案实现和通信接口设计.可应用于光栅位移的数据采集、处理、控制及与上位机的通信系统中.     

基于DSP与FPGA的便携式超声探伤仪

提出了一种基于DSP与FPGA方案的高性能超声探伤仪，FPGA可以在DSP的控制下进行在系统编程，因此，仪器可以根据不同需要采用不同信号处理算法，使得仪器非常灵活。DSP通过USB通信接口方便、高速地与计算机通信。介绍了系统组成原理和利用DSP的GPIO接口配置FPGA的方法与接口电路实现。实验表明，该系统可以实现复杂算法，并实现实时处理。     

基于FPGA的高速数据采集存储系统的设计与实现

为提高存储测试过程中的数据采集速率,增大存储容量,设计了一种基于FPGA的高速数据采集存储系统。该系统选用高性能FPGA作为控制核心,结合高速AD转换芯片和大容量FLASH存储器完成数据的采集与存储;时AD逻辑控制、缓存模块等关键技术进行了详细介绍。试验结果表明,该系统最高采样率可达1．7MS／s,能够很好地实现数据采集与数据存储功能,运行效果良好。     

多通道采集器的设计

为了满足声呐与语音信号处理中对多通道信号同步采集和采样率可变的应用需求,提出了一种基于高性能现场可编程逻辑门阵列(FPGA)的多通道采集器。该采集器使用FPGA作为控制器件进行模块化设计,采用24颗高精度模数转换器(ADC)AD7768,并结合上位机控制数据采集和数据处理,实现采样率可变的192通道并行数据采集功能。实验测试表明,该采集器同步性能优于25 ns,采样率可通过上位机配置切换,数据记录速率高达196 MB/s。     

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.