基于直接转矩控制的风轮模拟仿真研究

基于直接转矩控制理论分析和永磁同步电机直接转矩控制结构原理,借助MatLab/SimuLink工具,对永磁同步电机直接转矩控制系统各环节进行了仿真建模;基于直接转矩控制快速动态响应的特点,成功应用该控制系统进行风轮模拟仿真实验,获得了理想的风力特性输出曲线,验证了理论的正确性。     

采用神经网络控制的永磁同步电机调速系统

为改进传统PID控制的永磁同步电动机(PMSM)调速系统性能,设计了神经网络速度控制器并对其构成的矢量控制系统进行了仿真分析.结果表明,当电机参数改变或受到外部扰动时,该系统具有更好的动态性能.     

风力发电技术研究及发展

介绍了当前风力发电机的主要驱动方式和风力机的功率调节方式,阐述了恒速恒频、变速恒频发电技术的特点,论述了具有鲁棒性的非线性智能控制技术在风力发电中的应用。通过对比各种风力发电技术和各种控制方法的优缺点,对未来风力发电技术的发展趋势作了展望。     

ASON体系结构及存在的问题研究

介绍了自动交换光网络(ASON)--一种具有灵活性、高可扩展性的能直接在光层上按需提供服务的光网络的发展情况和技术特点,分析了ASON的体系结构,包括3个平面,3个接口、3种连接.最后指出了ASON在规范和应用中存在的问题.     

盘式永磁同步电机永磁体内涡流的有限元分析

钕铁硼是采用最多的永磁体材料,虽然性能令人满意,但电导率高,耐热性差;并且由于转子散热能力差,涡流会使永磁体发热升温,从而导致部分不可逆的退磁,因此很有必要对永磁体内的涡流进行分析。针对盘式永磁同步电机自身的特点,通过二维电磁场有限元法分别求解了空载和负载时电机内的磁场和永磁体内的涡流,其中包括有铁心电机由于齿槽的存在而引起的涡流和不同电机运行速度下的涡流。为了考虑电机的运动效应和使计算结果更加精确,采用了瞬态分析,同时在划分单元时考虑了磁场的透入深度。最后根据瞬态计算出的数据绘出了磁矢位和涡流波形。波形分析得出了影响永磁体内涡流的因素以及应采取的措施。     

外转子双凸极永磁电机电枢磁场对绕组电感特性的影响

根据电动汽车对驱动电机性能要求,结合双凸极电机的特点,提出一种外转子结构的双凸极永磁电动机。分别对电机空载、负载以及电枢磁场单独作用3种情况下进行了有限元分析,得出在1个永磁磁链周期内不同转子位置角和不同电枢电流作用下的磁场分布图以及静态参数特性曲线。从场的角度分析和说明了电枢磁场对绕组电感特性的影响,电机的静态参数也为该电机进一步的仿真分析提供了依据。     

Influence of oxygen content on grain growth in Pr–Fe–B/Nd–Fe–B sintered magnets

An investigation into the effects of intermediate/variable final oxygen contents, in relation to the resultant microstructures and final magnetic properties of Pr–Fe–B- and Nd–Fe–B-type magnets in the as-sintered state has been undertaken. For low oxygen contents the Pr–Fe–B and Nd–Fe–B sintered magnets exhibited excessive grain growth on sintering. A high oxygen content resulted in the elimination of abnormal grain growth for both materials, on sintering, where the level of oxygen contamination appeared to affect the grain growth process, although not the grain growth mechanism. Differences, however, in grain growth behaviour for the Pr–Fe–B and Nd–Fe–B sintered magnets have been observed. A changing oxygen content resulted in a variable grain size and grain size distribution for both the Pr–Fe–B and Nd–Fe–B sintered magnets, resulting in a progressive change in intrinsic coercivity, with oxygen content.     

Comparison of the univariate and multivariate methods in the optimization of experimental conditions for determining Cu, Pb, Ni and Cd in biodiesel by GFAAS

Experimental design was used as a tool to define the optimum pyrolysis and atomization temperatures for four analytes (Cu, Pb, Ni and Cd) in biodiesel samples. Two chemical modifiers (Pd + Mg and W) and two distinct sample preparation procedures (microemulsion and wet digestion in a focused microwave system) were also investigated. The pyrolysis and atomization temperatures were optimized using 2⁴ factorial design for Cu, Pb, Ni and Cd, with 16 assays carried out for each analyte. The results for Cu and Pb indicated that variables of sample preparation for digestion by focused microwave was the most important one for both analytes. The pyrolysis and atomization temperatures applied were 1000 °C and 2200 °C for Cu and 500 °C and 2000 °C for Pb. None of the variables analyzed here were important for Ni, and the pyrolysis and atomization temperatures chosen for this element were 800 °C and 2300 °C. A different factorial design was used for Cd. The variables of medium and modifier were not important for this element, and the lowest temperatures, Tp-500 °C and Ta-1400 °C, were chosen based on this second design. The importance of factorial design in the simultaneous optimization of several variables studied by GFAAS was confirmed, for it involves fewer experiments and hence, lower costs, greater speed and higher efficiency.     

带式永磁磁选机选别攀枝花钛铁矿的试验研究

新型带式中强磁场永磁磁选机选别攀枝花钛铁矿的小型试验研究表明：磁尾分级后，经一次选别作业可得TiO2品位15％左右，回收率80％以上，丢弃尾矿产率40％左右的较好指标。该设备具有处理能力大、生产费用低、占地面积小、操作管理方便等优点，是该矿石粗粒级的理想粗选设备。