汇川技术HD92高压变频器在皮带机多电机功率平衡上的应用

本文介绍了汇川HD92皮带机专用高压变频器在宁夏某煤矿主井(斜井)皮带机上的应用并从电气原理、性能、节能分析等各方面对高压变频器在皮带机上的应用做总结     

基于CPLD电压空间矢量调制的逆变电源

介绍了利用EDA软件及美国ALTERA公司的ACEKlK芯片，基于磁链轨迹跟踪法，来实现变频逆变系统。试验证明，用现场可编程门阵列(FPGA)来实现这种调制是非常简单和有效的。     

基于MATLAB的四杆变幅机构结构参数分析

本文介绍利用MATLAB[1]数值计算和数据可视化功能对门座式起重机四杆变幅机构结构参数进行分析,各参数变化时对运动规律的影响。     

机器人机构的精度优化设计

本文应用最优化技术,确定能满足机器人绝对精度要求的,并使制造成本最低的连杆参数的最优公差值.建立了机器人机构精度优化设计的数模,并针对一个带闭链的五自由度机器人,在不同精度指标,不同概率水平以及不同原始误差分布下,进行了连杆参数公差的优化计算。     

平面连杆机构极位夹角定义的探讨

急回平面连杆机构实现了机构工作行程的慢速进给和空间行程的快速退回，从而提高了生产率，而平面连杆机构的急回特性与其极位夹角θ密切相关，现行的众多教科书中对极位夹角的定义和锐角的取值范围，限制了书中所确定的行程速比系数k与极位夹角θ的关系式的通用性，本文对极位夹角θ的新定义解决了这个问题，并通过实例说明了其正确性和可行性。     

Mining Web Log Sequential Patterns with Position Coded Pre-Order Linked WAP-Tree

Sequential mining is the process of applying data mining techniques to a sequential database for the purposes of discovering the correlation relationships that exist among an ordered list of events. An important application of sequential mining techniques is web usage mining, for mining web log accesses, where the sequences of web page accesses made by different web users over a period of time, through a server, are recorded. Web access pattern tree (WAP-tree) mining is a sequential pattern mining technique for web log access sequences, which first stores the original web access sequence database on a prefix tree, similar to the frequent pattern tree (FP-tree) for storing non-sequential data. WAP-tree algorithm then, mines the frequent sequences from the WAP-tree by recursively re-constructing intermediate trees, starting with suffix sequences and ending with prefix sequences.This paper proposes a more efficient approach for using the WAP-tree to mine frequent sequences, which totally eliminates the need to engage in numerous re-construction of intermediate WAP-trees during mining. The proposed algorithm builds the frequent header node links of the original WAP-tree in a pre-order fashion and uses the position code of each node to identify the ancestor/descendant relationships between nodes of the tree. It then, finds each frequent sequential pattern, through progressive prefix sequence search, starting with its first prefix subsequence event. Experiments show huge performance gain over the WAP-tree technique.     

永磁同步电机的无速度传感器直接转矩控制

在高性能的永磁同步电机控制系统中,机械传感器的存在会使系统的成本增加,可靠性降低,容易受到外部环境的影响.在叙述永磁同步电机直接转矩控制原理的基础上,采用了一种基于转子磁链的转速估计方法,该方法根据定子磁链角和负载角确定出转子磁链角,进而估计出电机的转速.仿真和实验结果验证了该方法能够在电机全速范围内准确地估计出转速,具有优良的动静态性能,适合于永磁同步电机的直接转矩控制.     

电机空间电压矢量控制的研究

介绍空间电压矢量控制同步电机的概念及其发展情况,对其原理作了详细的阐述,针对SVPWM控制指出了需要改进的地方并对其应用作了展望。     

减少弃水窝电现象的分时电价联动模型

基于四川雅安径流式小水电的电源特点和发售电两侧均已长时期实行丰枯—峰谷分时电价的市场特点,结合发售电两侧电价联动的理论基础,提出了一种新的分时电价联动模型。在不损害发电公司、电网公司、用户三方利益的前提下通过价格联动减少弃水电量,增加社会效益。