MW级交流传动方案的可靠性和可利用率

在工业生产领域，生产设备的可靠性对工厂赢利能力具有很大的影响，这类生产设备如轧钢机、压力机、压缩机、泵、鼓风机等。同时，这些机械越来越多的采用了兆瓦级调速传动系统（VSDS）。因此，在上述应用领域，对调速传动系统的可靠性要求也变得格外高。本文对几种不同的大功率中压传动方案的可靠性进行了比较，如负载换相型逆变器、电压型逆变器和功率单元级联型变频器。作为一种提高可靠性的手段，对冗余的概念进行了介绍，同时也讨论了实现调速传动系统冗余的方法。除了器件可靠性和采取冗余措施外，不同的维护保养方法对于调速传动系统的可靠性也有一定的影响。最后，要本文给出了传动方案的选择和保养维护方法的建议。     

云计算关键技术之弹性伸缩控制技术认知研究

云计算的弹性伸缩控制技术因其以弹性可伸缩方式提供资源,提高了资源利用率和用户满意度,较好地解决了资源利用率和应用系统之间的矛盾,而成为云计算的关键技术.弹性伸缩控制技术,是指对一个系统适应负载变化进行调控的能力.弹性伸缩有纵横之分,弹性伸缩的需求是刚性、动态的.虚拟化技术的应用,使得弹性伸缩控制技术的优势发挥得更加充分.在弹性伸缩控制技术支持下,整合了动态负载均衡及资源配置机制的云计算中心,可以很好地解决大规模系统的有效管理问题,具有良好的应用前景.     

Smith预估补偿在随动系统教学中的探讨

针对位置传动系统的高速响应性和机械负载的低频强扰动,本文设计了Smith预估补偿调节器,分析了预估补偿对输入信号的跟随性和对扰动信号的抑制能力。     

变频调速在熟料窑传动系统中的应用

本文详细阐述了熟料窑负载特性，指出分析了直流传动系统存在的弊端，提出了熟料窑交流变频调速系统解决方案，该方案在熟料窑电气传动系统中得到了成功应用。     

一个基于弹性云的负载均衡方法

提出了一种基于弹性云的负载均衡方法.这一方法构造了负载均衡模型框架,建立了模型对于虚拟机负载状况和虚拟机集群资源利用率进行量化评估,为实现任务的分发和虚拟机集群的弹性伸缩,设计了任务调度算法和弹性伸缩算法.实验结果表明基于弹性云的负载均衡方法在实现负载均衡的同时,有效提高了资源利用率.     

森兰变频器在水泥回转窑主传动上的应用

本文介绍了森兰变频器在水泥回转窑主传动上的应用。水泥回转窑主传动采用变频调速,要考虑回转窑的负载特点和运行特点。并以实例说明水泥回转窑主传动系统变频改造后,系统运行性能得到改善,节能效果显著。     

变频器在金属轧制传动中的应用

轧制传动是变频器高端应用领域,本文希望通过介绍轧制传动对变频器的要求及现状,帮助我国变频器制造企业改进自己的产品,逐步打入该领域。文中分别介绍了轧制传动用大功率、大中功率和中小功率变频器的特点、现状及要求。介绍了主传动及6种付传动和加工线传动对工艺控制的要求。介绍了多质量传动和有弹性机械联系的多电机传动两类弹性系统的轴扭振产生机理和抑制方法。     

基于遗传优化RBF神经网络的电动负载模拟器控制

针对炮控系统电动负载模拟器存在的摩擦、间隙、弹性形变、对象参数时变和位置扰动等复杂非线性,传统的控制方法难以得到良好的动静态性能指标。结合电动负载模拟器系统组成和工作原理,建立了加载数学模型,利用炮控系统位置控制信号进行前馈补偿,设计了RBF神经网络控制器,并采用改进遗传算法对控制器的权值、节点和中心矢量等参数进行优化。实验结果表明:该控制策略能够有效抑制多余力矩,保证了系统静、动态加载时的控制精度和稳定性。     

光学相干弹性成像研究现状与展望

弹性成像技术是以软组织的杨氏模量、剪切模量、应力与应变等弹性参量为成像对象的技术。伴随着光学相干层析成像(OCT)的发展,光学相干弹性成像(OCE)由于其微米级别的分辨率,实时的图像处理以及非侵入式成像得到人们的青睐。综述了OCE的分类以及当今主流的几种OCE技术及其弹性图像重构的问题。探讨了OCE中施加机械负载方法和位移估算、应变估计的方法。OCE对检测组织临床上和病理上的机械特性拥有强大的潜力,特别是在诊断癌症,心血管疾病和眼科疾病上。总结了OCE研究和发展状况,并对其发展前景进行了展望。     

基于残差观测器的电机迭代学习控制系统

文中设计一种残差观测器下电机迭代学习的控制方法,建立传动系统的机电耦合模型,在基于观测器的残差生成器控制框架下进行转速补偿的迭代学习控制,提高了电机调速系统在负载扰动影响下的鲁棒性能和抗干扰性能。仿真结果表明,该控制系统能够有效减小负载扰动下的电机转速变化幅度,提高了闭环控制系统的稳定性。     

Dynamic and Vibration Analysis of a Multimotor DC Drive System With Elastic Shafts Driving a Tissue Paper Machine

In this paper, the influence of the stiffness and damping of real elastic shafts on the behavior of a multidrive system driving a tissue paper machine is investigated. The drive system consists of four DC motors, where two of them drive the Yankee drying cylinder and the other two drive the presses section. Six-pulse thyristor bridge power converters that are connected to the same power transformer supply the motors. The inertias of the motors and the driven machines, in conjunction with the shaft stiffness, form mechanical resonators. Thus, resonance phenomena may occur, which may lead to undesirable results. This particular case results to two three-mass and one five-mass systems. This paper presents an analysis of the resonance frequencies of two sections of the machine during startup and machine production, considering the shaft stiffness (shaft diameter, length, and thickness). The elastic shafts eliminate the ripple of the motor electromagnetic torque, which is transferred to the driven machine. The behavior of elastic shafts with different stiffness in the transmission system is studied. Moreover, the steady state and dynamic behavior of the system considering the influence of the elastic shafts and vibration analysis were investigated using simulation. A model algorithm for system simulation was developed using the MATLAB/SIMULINK software. Characteristic simulation results are presented and are expressed in terms of speed and torque response. Considering the resonance frequency analysis and simulation results, mechanical design guidelines can be given for the most significant drive components in order to avoid torsional oscillation resonance phenomena and minimize torsional oscillations of the drive system.     

Performance Improvement of Industrial Drives With Mechanical Elasticity Using Nonlinear Adaptive Kalman Filter

This paper deals with the application of the adaptive control structure for torsional vibration suppression in the drive system with an elastic coupling. The proportional-integral speed controller and gain factors of two additional feedback loops, from the shaft torque and load side speed, are tuned on-line according to the changeable load side inertia. This parameter, as well as other mechanical variables of the drive system (load side speed, torsional and load torques), are estimated with the use of the developed nonlinear extended Kalman filter (NEKF). The initial values of the Kalman filter covariance matrices are set using the genetic algorithm. Then, to ensure the smallest state and parameter estimation errors, the on-line adaptation law for the chosen element of the state covariance matrix of the NEKF is proposed. The described control strategy is tested in an open and a closed-loop control structure. The simulation results are confirmed by laboratory experiments.     

时变质量梁系统的振动主动控制研究

为了保证机械臂运动的高精度、准定位,采用主动控制技术降低结构的干扰振动是一项迫切而紧急的任务。该文以含变质量构件的弹性梁系统为对象,开展变质量弹性结构的振动特性研究和振动主动控制研究。使用模态叠加法推导了粘贴有压电片的变质量-柔性梁组合结构的控制方程,通过仿真获得变质量弹性梁系统的振动特性和运动规律。然后设计反馈控制器对质量增大系统和质量减小系统进行了振动主动控制,并采用时频分析技术分析了控制效果。仿真结果表明,变化的质量在引起系统振动频率改变的同时,还引起了一个附加的阻尼。在变质量时变系统的共振频率区间,通过反馈控制可有效抑制结构的振动。     

基于声波驱动的高速变焦液体透镜振动特性分析

高速变焦液体透镜在快速移动物体的目标捕捉方面具有重要的应用.高频声波激励方法在理论上能够实现毛细腔边沿(靠表面张力)约束液滴的高速往复运动,但是相关工艺试验研究是目前该技术成熟应用的关键.文章在对毛细腔贯通液滴共振理论分析的基础上,基于3D打印技术开发了一种采用双源声波激励毛细腔贯通液滴进行振动的实验装置.在分析能量损失的基础上,采用激光多普勒测振仪分析了相关工艺参数对毛细腔贯通液滴振动频率和振幅的影响,总结了相关规律,为实现高速变焦液体透镜技术的应用奠定了基础.     

高炉料车卷扬电力拖动方案原理的分析和比较

本文面向炼铁高炉主卷扬电力拖动方案，通俗简介了各种电机电气传动方式和它们的特点，重点分析了绕线电机串阻调速，直流电机调速和交流电机通用变频调速的适用性和优缺点，特别指出了变频调速的节能优势及应用中存在和应注意的问题。     

Analysis of Performance of Adjustable-Speed Drives during Voltage Sags

The induction motors are the most common electric machines on industrial systems and with extended applications when adjustable speed drives (ASD) are used. The speed drives are based on power electronic devices and therefore they are highly sensitive to electric disturbances such as voltage sags, interruption, etc. Voltage sags has become one of most common power quality problems in the electrical systems, producing negative effects mainly in loads with power electronic technology. In this paper, the analysis of the effects produced by voltage sags in the ASD and the induction motor are presented. The electric system used for the analysis is conformed by an induction motor, an AC drive with V/Hz control scheme and a step down transformer connected in Yd. The voltage sags were produced by faults in the electric system with a time duration of 6 cycles (0.1 s). The whole electric system was modeled and simulated in Matlab/Simulink environment. The operating conditions of the induction motor was 80% of nominal speed and full load. The obtained results show high sensitivity of the drive, mainly to the dc-link voltage drop, resulting in a motor speed drop and overcurrents in the drive feeders at the ending sag. The adopted parameters used as a limit for the speed drive disruption were 5% of variation in the motor speed and 1.5 p.u. for the peak current. The most severe effects occur with sags type A and G due to three-phase and two-phase to ground faults respectively. The effect of these sags produced a dc-link voltage drop higher than 30% and therefore the drive disruption as a result of the operating limits exceeded. With voltage sags type C and D, caused by single-phase to ground and two-phase faults respectively, the effects produced in the drive and the motor are negligible.     

周期性压电分流薄板结构振动控制方法研究

为降低薄板振动产生的辐射噪声,采用将分流压电振子周期性固定于薄板上的方式进行振动控制,因结构符合周期性所以能够衰减压电薄板的振动量从而抑制薄板产生的辐射噪声。分别利用有限元法和传递矩阵法建立分流压电薄板的理论模型和弹性波传播理论模型,分析了压电薄板对振动衰减的原理,研究了3种分流电路调谐频率对压电薄板振动衰减的影响。结果表明,当电路调谐频率为850Hz时,压电薄板的振动衰减量最大。     

回转窑改用变频驱动的几个技术问题

回转窑原使用直流马达驱动。改用变频驱动后,产生了整流变利用,工频下的马达无法与原转速一致,窑体的起动,新老系统之间是否会产生干扰等诸问题,本文力图充分利用变频器的工作特点,优化设计,解决以上几个方面的技术问题。     

大型同步电机交交变频调速系统对电网的谐波影响分析

针对热连轧机组中同步电动机主传动的交-交变频调速系统,定量分析了同步电机负载经由交交变频器对变压器供电网侧产生的谐波影响.分别对不同的负载参数、变压器原副边电感量和变流装置的进线电抗器参数的情况进行了仿真分析.同时,对大型多组交交变频器移相组合式供电进行了数据移位方式仿真.并且对交-交变频器和交-直-交变频器所产生的谐波干扰进行了对比分析.仿真结果表明调节变压器原副边电感量再结合移相组合式供电的方法可以有效地降低大型同步机负载对供电网侧的谐波干扰,并使得总谐波率在各相中分布趋向均衡.     

浅谈西门子6SE70系列变频器结构与故障分析

在现代工业日益发展的今天,变频调速以被公认为最理想、最有前途的调速方式之一,成为改造传统工业、改善工艺流程、提高自动化水平、推动技术进步的重要手段,广泛应用于工业自动化的各个领域。我单位1580热轧生产线辅传动系统采用西门子6SE70系列变频器,对应用过程中出现的各种故障报警维修实践经验,加以总结概括,供有关维修人员借鉴。