永磁同步电机无传感器直接转矩控制

传统直接转矩控制转矩、磁链和电流脉动较大,速度传感器的安装容易使系统可靠性降低、成本增加.为解决以上问题,采用扩展卡尔曼滤波器对定子磁链进行观测,并对转速进行估计,实现表面式永磁同步电机无速度传感器直接转矩控制,克服传统直接转矩控制中积分器的缺陷,保持直接转矩控制固有的转矩响应快和系统鲁棒生强的优点,能够对电机参数变化、负载扰动具有较强的鲁棒性,有效地改善了系统的动、静态运行生能,仿真和实验验证了该方法的可行性和有效性.     

Divisional and hierarchical innervations of G. gecko’s toes to motion and reception

As a member of robot families, climbing robots have become one of the research hot-spots in the robotic field recently and Gekko gecko （G. gecko） has been broadly seen as an ideal model for climbing robot development. But for gecko-mimic robots, one of the key problems is how to design the robot＇s foot. In this paper, （1） high-speed camera recording and electrophysiological method are used to observe motion patterns of G. gecko＇s foot when it climbs on different oriented surfaces; （2） nerve innervations of gecko＇s toes to motion and reception are studied. It is found that the five toes of the G. gecko can be divided into two motion and reception divisions, and also its motion and reception are modulated and controlled hierarchically. The results provide important information and exclusive ideas for the foot design and control algorithm of gecko-mimic robots.     

Effect of different atmospheres on dry friction behavior of steel sliding against brass at high speed

The atmosphere components have an influence on tribological behaviors of tribo-pairs. Through changing the atmosphere component, the effect of atmosphere component on the tribological behaviors of CrNiMo steel against brass at high sliding velocity was investigated. The wear test was carried out on a high-speed friction and wear test rig whose test atmosphere could be controlled. The tests were performed at four sliding velocities （30, 40, 50, 60 m/s）, one contact pressure （1.33 MPa） and two atmosphere components （N2 or O2）. The morphologies of the worn surfaces of various pins were observed with a scanning electron microscope. The chemical compositions of the surfaces and subsurfaces for steels were determined with an energy dispersion spectroscopy. The results showed that the wear rate of the steel pins were low all the time with the sliding velocity increasing in oxygen atmosphere, and that the wear rate of the steel pin in nitrogen atmosphere was higher than that of the steel pin in oxygen atmosphere. It was found that the thin and compact oxidation layer formed on the worn surface of the steel in oxygen atmosphere played a key role in wear resistance. However, the wear rate of the steel pin increased rapidly with the sliding velocity increasing in nitrogen atmosphere, which was attributed to the thick and loose surface layer formed on the worn surface of the steel.     

大型舰船上子惯导速度的精确计算方法

针对大型舰船上,子惯导速度精确计算的需求,提出了利用杆臂长度、载体角速率构造主惯导在子惯导安装位置处伪速度观测量的算法.针对杆臂效应力学补偿法中需要已知杆臂长度的要求,并结合大型舰船挠曲变形带来的杆臂长度时变特点,提出将杆臂长度误差增列为系统状态向量,通过在线补偿的方法准确获取杆臂长度.仿真结果表明,杆臂长度在线补偿方法对杆臂长度的估计可以精确至厘米级,从而有效提高了伪速度观测量的精度,使得子惯导3个方向的速度均值可以精确至厘米级,均方差可精确至分米级.     

暂态电压失稳模式主导不稳定平衡点的计算

构建了负荷采用三阶感应电动机并联恒阻抗动态模型时电力系统暂态电压稳定分析的数学模型。针对采用牛顿法求取故障后系统电压失稳模式主导不稳定平衡点（CUEP）存在的初值确定难题,提出了一种实用的解决方案：通过判别给定故障的主导负荷母线,对主导负荷母线以外系统由故障后稳定平衡点处的状态进行戴维南等值,对负荷中感应电动机部分采用其稳态等值电路,再由感应电动机的转矩特性求得CUEP附近的一个点作为迭代初值,以计算CUEP;并且,还给出了如何得到更接近CUEP的迭代初值以更可靠求得CUEP的方法。IEEE 9节点系统和IEEE 39节点系统的计算结果验证了该方法的可靠有效。     

一种直流电机数字控制系统的设计与实验研究

介绍了一种直流电机控制系统,该系统以TMS320F2812 DSP芯片作为核心处理单元,搭建了驱动、采样、保护等硬件电路,利用TMS320F2812的高速运算能力,实现电流、速度双闭环的全数字PI调节、PWM控制等算法.试验结果表明,整个系统稳定、可靠、实时性良好,为数字脉宽调制系统提供了一种可行的方案.     

一种实用超声马达驱动电路的设计和制作

超声波马达是一种借助摩擦传递弹性超声波振动以获得动力的驱动结构。超声波马达需要专用电源供电,在实验室中只要具有信号发生及放大装置即可满足这个要求,而当马达作为某个装置的部件时,就需要配置专用的可移动电源器。针对实验室利用压电材料所研制的新型超声波马达,设计和制作出了一种专用驱动电路。该驱动电路由干电池提供直流电源,产生频率范围为10-100kHz,电压峰峰值为0-180V可调的超声波信号。实验结果表明,研制的电路性能稳定,能方便地驱动超声波马达,并良好运转。     

振动片倾角对超声波电机性能的影响

以振动片式驻波超声波电机为研究对象,设计并制作两台不同结构尺寸的样机,就不同倾角振动片对电机性能的影响进行对比实验.结果发现,振动片的角度值也存在一个最优的匹配范围,预压力有一个最佳的匹配值,以及换能器的预紧力大小对电机输出的影响十分敏感.在一定条件下(如驱动频率、振动片倾角、定转子间的预压力等),振动片式驻波超声波电机能够实现转子的反转效果.说明一般认为该类型电机只能单向驱动的结论并不准确.此外,转子的正反转效果与驱动频率、振动片倾角、定转子间预压力等因素有关.     

基于遗传算法的三环无刷直流电机控制系统研究

针对无刷直流电机的位置跟踪问题,借助于噪声滤波器、电机本体和三环PI控制器,设计电机位置跟踪模型,并借助改进的遗传算法确定PI参数的次优值,提供了一种基于智能优化技术的无刷直流电机位置跟踪控制系统设计方法。数值实验比较显示,该方法较之传统的参数整定方法更可行,能使控制系统的输出响应跟踪更快及无超调量。     

低浓度颗粒流Boltzmann方程的同伦分析方法解

同伦分析方法(homotopy analysis method, HAM)是求解强非线性问题的有力手段. 针对颗粒流的动理学理论中的非线性微分积分方程——?Boltzmann方程, 采用 HAM方法选取局域Maxwell速度分布函数作为初始猜测解, 得到了低浓度颗粒流的Boltzmann方程的一阶近似解, 与传统的Chapman-Enskog方法得到的一阶近似解表达式的结构一致, 初步显示了HAM方法求解Boltzmann方程的有效性, 为一般Boltzmann方程的HAM方法求解奠定了基础.