电机定子结构及其绝缘介电常数的频率特性对定子绕组电容值的影响

确定电机定子线棒的高频参数对于研究局部放电信号在电机绕组中的传播特性及研究PWM逆变器驱动的交流电机的定子绕组电压分布有重要意义。文中对大型汽轮发电机定子线棒的电容做了比较详细的研究,内容包括:对电机定子线棒复合绝缘等值介电常数的频率特性的测试研究、采用数值计算方法计算出用铝箔纸裹住的电机定子线棒的多导体传输线模型的单位长度电容、线棒股线间薄绝缘对电容的影响、对铁心硅钢片叠片间隙对电容的影响等。其数值计算结果与之前测量得到的电容值比较吻合,这也证明了通过测量开路阻抗、短路阻抗来得到电机定子 线棒分布参数的试验方法是有效的。

基于有限元方法的相对介电常数和电阻率对套管状态参数的仿真计算研究

深入开展绝缘材料的电阻率和介电常数对变压器套管的状态参数(如电容、介质损耗和绝缘电阻)的影响研究,对提高套管的故障诊断和变电站主变压器的安全可靠性运行具有重要的意义。为此,基于有限元方法开展了相对介电常数和电阻率对套管电容、介质损耗和绝缘电阻的仿真计算研究,通过研究发现:套管中油的介电常数和电阻率对套管电容、介质损耗和绝缘电阻影响较小,而两个电容屏之间油纸绝缘的相对介电常数和电阻率对套管电容、介质损耗和绝缘电阻影响较大。

低k介质对CMOS芯片动态功耗的影响

利用CMOS电路动态功耗模型,对采用不同介电常数绝缘介质的CMOS集成电路进行模拟,研究了不同特征尺寸集成电路中低介电常数绝缘介质薄膜对电路动态功耗的影响。发现集成电路特征尺寸越小,电路功耗-延迟积与金属互连长度的线性关系越好。并且随绝缘介质介电常数降低,电路动态功耗的两个部分:状态翻转功耗与直通短路功耗,都有明显的降低。因此在ULSI中采用低介电常数绝缘介质是降低电路功耗的一种十分有效的途径。

风力发电低频输电用变压器的关键技术

根据频率对变压器的影响,提出了频率50/3Hz下变压器的特点和其性能参数的计算方法。通过测试频率50/3Hz下硅钢材料的特征曲线,提出了铁心设计的思路。根据测试频率50/3Hz下绝缘材料的介电常数,提出了50/3Hz下的绝缘结构。

Modeling porous structure of oil-pressboard interface and its effect on electric field distribution

The oil-pressboard insulation is a typical composite insulation system widely used in the design and manufactory of large power apparatus. The implement of oil-pressboard insulation may lead to surface electrification and discharge at the interface under certain condition. It is of significant importance to take an insight into the phenomenon occurring at the interface. Through experiment, the pressboard is found as a porous material. The interface changes abruptly from bulk pressboard to the bulk oil as a result of the porous structure. A new model is proposed which divides the interface into bulk oil region, transition region, and bulk pressboard region. The width of the transition region is decided according to the microtome figure. The effective permittivity of the transition region is calculated using a new model based on fractal theory. The model is validated and compared with previous calculation model. The effect of the existence of transition region on the electric field distribution is discussed.