基于单神经元自适应的 PWM 整流器控制方法研究

针对 PWM 整流器在传统双 PI 控制中存在非线性、高次谐波和抗扰性差等缺点,以三相电压型 PWM 整流器为研究对象,提出了一种单神经元自适应 PID 与传统 PI 复合的新型控制策略。以电压外环误差限作为调节器切换依据,在误差限值以上利用神经元自学习、自整定算法输出动态可变的 PID 参数调节电压,在误差限值以下采用 PI 调节器快速减小静差,同时在电流内环引入前馈解耦策略实现电压、电流双闭环控制。对系统进行了仿真实验,结果表明这种控制方法能有效改善电压的抗扰性和电流的跟随性,提升电能质量并减小谐波污染,系统动静态性能良好。     

基于线性自抗扰的永磁同步电机速度控制研究

针对传统永磁同步电机速度控制采用双闭环比例积分控制算法,存在参数适应性差、抗干扰能力不足等问题,设计了一种基于线性自抗扰的永磁同步电机速度控制策略.采用这一控制策略,内环控制器和外环控制器均采用一阶线性自抗扰控制.仿真结果表明,基于线性自抗扰的永磁同步电机速度控制只需要整定带宽参数,与传统比例积分控制相比,具有转速抗干扰能力强、控制鲁棒性强的优点.     

三相PWM整流器PI调节器设计分析

建立了三相PWM整流器在两相同步旋转坐标系（d—q坐标系）中的数学模型,采用前馈解耦控制双闭环控制策略,实现了输入电流跟踪指令电流,输出稳定直流电压,给出了电流内环和电压外环的PI调节器的设计。最后在MATLAB／SIMULINK中进行了三相PWM整流器系统的仿真实验,结果验证了PI调节器设计的正确性。     

一种MFAC补偿的无串联型DVR复合控制策略研究

对无串联型DVR的逆变器控制策略进行研究,针对滤波电容电流内环、电压瞬时值外环的双闭环PI控制在快速性和精确电压补偿方面的不足,提出在双闭环PI控制的外环增加无模型自适应控制,形成复合控制算法,以提高控制器对信号的跟踪能力。通过Matlab/Simulink的建模仿真,表明该复合控制算法具有动态响应速度快、输出电压稳态精度高等特点。     

三相PWM整流技术在电动汽车中的应用

建立了三相PWM整流器的数学模型,通过Park变换将abc三相静止坐标系转换到dq两相旋转坐标系,设计了三相PWM整流器的双闭环控制系统,同时给出了电压外环和电流内环的PI调节器的设计方法。采用前馈解耦控制方法,实现了输出稳定的直流电压,提高了系统的鲁棒性。最后通过MATLAB/Simulink对三相PWM整流器模型进行了仿真,证明了所建立模型的正确性。     

基于电流解耦控制的光伏并网系统仿真分析

光伏并网发电是太阳能利用的重要途径,而并网逆变器结构的选择和控制策略的改进是其研究的重点。在PSCAD/EMTDC平台上搭建了单级三相光伏并网系统的仿真模型,仿真模型中的并网逆变器采用双闭环的控制策略,其中电流内环根据非线性控制理论中反馈线性化的思想,实现电流的解耦控制,电压功率外环采用PI控制。仿真结果表明:该控制策略不仅控制精度高,稳定工作域大,并且必要时能在一定范围内对配网的无功进行调节,提高配网稳定性。     

基于滑模自抗扰控制的开关磁阻电机调速系统

开关磁阻电机的双凸极结构和开关电源供电方式使其电磁场存在非线性饱和特性，致使其运行时转矩脉动大，传统控制方法很难完成平稳调速。针对该问题，提出开关磁阻电机调速系统的滑模自抗扰控制策略。首先，内环根据开关磁阻电机数学模型设计自抗扰电流控制器，提高电流的响应速度和鲁棒性；其次，外环设计滑模速度控制器取代传统的PI控制器，并证明了系统的稳定性，增强了速度的鲁棒性；最后利用仿真与实验验证该控制策略的有效性。与传统的开关磁阻电机调速系统控制策略对比，能有效改善启动电流过大、转速超调和转矩脉动问题，提高了系统的响应速度和鲁棒性。     

地基大口径望远镜伺服系统的抗扰动设计

针对地基大口径望远镜伺服系统的抗扰动问题,提出了一种抗扰动控制算法。该算法采用双闭环控制结构:内环为高带宽的电流环,采用PI控制器;外环为速度环;采用线性自抗扰控制器,通过线性扩张状态观测器辨识出系统扰动,然后将该扰动前馈到系统控制量中去,构成复合校正系统。为解决大动态输入引起的控制器饱和问题,状态观测器的输入控制量加入了抗饱和控制算法,保证了系统的稳定性和良好的动态特性。仿真和实验结果表明:与传统的PI控制器相比,引入抗饱和功能的自抗扰控制器在高低速均可以获得良好的动态性能;在低速平稳跟踪实验中,速度波动误差(RMS)由0.000 68(°)/s降低到0.000 32(°)/s。实验结果证明提出的方法能够有效提高伺服系统抗扰动能力和速度跟踪的平稳性。     

基于变论域模糊PI的三相PWM整流器控制策略设计

针对三相PWM整流器在启动时直流侧电压超调量较大,并且其动态性能容易受到自身参数变化和负载扰动的影响,提出一种基于变论域模糊PI的自适应控制策略。在模糊PI控制基础上,通过引入变论域伸缩因子来提高模糊规则的利用率,并将其应用到三相PWM整流器的电压外环当中,提高三相PWM整流器的自适应能力。仿真实验表明,与传统PI控制和常规模糊PI控制相比,所提控制策略具有动态响应快、无超调和抗干扰能力强等优点,验证了该控制策略的正确性和有效性。     

基于鲸鱼优化算法的双向LLC谐振变换器控制参数优化

LLC谐振变换器因其具有高频化、高效率和高功率密度等优点,近年来被广泛使用。但因其电路特点,LLC谐振变换器存在输出电流纹波大、动态响应性能不佳以及抗干扰能力差等问题。针对上述问题,提出一种基于鲸鱼优化算法的双闭环控制方法。双向LLC谐振变换器电压外环采用PI控制,电流内环采用自抗扰控制器,通过鲸鱼优化算法对PI控制器和ADRC(Active Disturbance Rejection Control)控制参数进行在线整定。最后通过MATLAB\Simulink进行仿真,验证所提控制算法的准确性和有效性。     

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...     

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.     

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。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

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.