饱和铁心型限流器限流阻抗试验和计算

计算大电流下的阻抗值必须考虑铁心的非线性磁化特性。而实际铁心的磁化特性与铁心材料本身的磁化特性可能有一定偏差,这会导致计算的误差。本文根据系列限流铁心电抗器的实验结果,分析了电流大小、铁心绕组参数与限流器阻抗值的关系,并且给出了一种从小型试验样机实验结果中提取出铁心等效磁导率,进一步利用经验公式和拟合外延法来计算饱和铁心型限流器在大电流下阻抗值的方法。该方法简单易行,方法的准确性得到了不同尺寸限流器的实验验证。     

基于爱泼斯坦方圈测试的硅钢片磁化曲线特性分析

带铁心的线圈类产品要实现准确的仿真设计最核心的内容是铁心的磁化曲线分析。本文通过爱泼斯坦方圈测试方法,测试了取向硅钢片B30P105的磁化曲线特性,分析了取向硅钢片轧制方向和垂直于轧制方向的磁化曲线、不同频率下的磁化曲线和铁心损耗。本文还制作了三种不同叠置方式下的铁心线圈,测试了它们的磁化曲线和铁心损耗曲线,并进行对比分析。通过本文硅钢片磁化曲线测试分析,对带铁心的线圈类产品仿真设计具有重要的工程意义。     

电力变压器全斜接缝叠片铁心工作条件下的磁性能模拟

在标准条件下,通过测量得到的电力变压器叠片铁心材料的磁性能数据,不能完全反应实际工作状态下材料的真实电磁性能。本文建立了两个产品级的叠片铁心模型模拟电力变压器铁心的实际工作状态,两铁心采用相同的材料和接缝型式,具有相同的截面面积,但柱轭的长度不同,采用双铁心方法获取电力变压器叠片铁心工作条件下的综合磁性能。得到了包括有效磁路长度,磁化曲线,损耗曲线以及铁心接缝区和柱轭区的励磁伏安等磁性能数据,有助于提高电力变压器产品的电磁分析和优化设计。     

直流偏磁下不同磁化曲线对变压器铁心损耗仿真的影响

直流偏磁下变压器铁心材料磁化特性采用不同的表述方式,将会产生不同的损耗仿真结果。本文基于爱泼斯坦方圈试验测量了30ZH120取向硅钢片的交流磁滞回环和交流偏磁磁滞回环,详细阐述并解释了交流磁化曲线、直流磁化曲线、平均磁化曲线、交流偏磁磁化曲线和交直流共同作用下磁化曲线的提取方法。从实验数据和理论分析的角度指出了交直流共同作用下磁化曲线与直流磁化曲线是同一条曲线。以两台干式变压器产品模型为例,设计并搭建了使变压器工作在直流偏磁条件的实验电路,测试并仿真计算了直流偏磁下电力变压器铁心的空载损耗。研究表明,计算分析直流偏磁电工设备时,可以用直流磁化曲线描述硅钢片材料的磁性能,为提高直流偏磁下变压器损耗仿真准确性提供了参考依据。     

电力电流互感器铁心磁滞回环的拟合

借助于人工神经网络（ＡＮＮ）的方法,建立了电力电流互感器（ＣＴ）铁心磁化特性仿真数学模型。与其它模型相比,该模型不仅解决了以往铁心磁化曲线拟合中的光滑性与精确性相互矛盾的问题,而且满足铁心磁化曲线拟合的稠密性要求。曲线拟合结果与样本数据的对比表明了该模型的正确性和有效性。     

交直流共同励磁时铁心磁场及损耗的数值计算研究

依据交直流共同励磁时铁磁材料磁化特性和损耗特性的描述方法 ,提出了利用交直流叠加磁化曲线和比总损耗曲线 ,计算交直流共同励磁时铁心磁场及损耗的数值计算方法。设计了测量铁磁材料交直流叠加磁化曲线和比总损耗曲线的双爱波斯坦方圈装置 ,并用它验证了上述算法的正确性。     

基于J-A模型的电工钢片磁致伸缩特性模拟与实验

电工钢片的磁致伸缩现象是引起电机、变压器铁心振动的一个重要原因。磁致伸缩特性与铁心的磁化方式密切相关。电机定子铁心存在大量旋转磁场,相比于交变磁化,旋转磁化会引起更大的磁致伸缩应变,准确模拟旋转磁化下电工钢片的磁致伸缩特性是实现电工产品性能优化的前提和基础。该文借鉴Jiles-Atherton(J-A)磁滞模型对磁化过程中磁畴畴壁移动和磁矩转动而产生滞后行为的表征方法,提出一种能够描述旋转磁化下磁致伸缩正应变和剪切应变矢量、滞后特性的磁致伸缩模型。基于电工钢片旋转磁特性测量系统提供的特性数据,采用粒子群优化算法实现了模型参数辨识,并验证了模型的准确性。制作并搭建硅钢叠片铁心局部磁致伸缩特性测量系统,给出了所提磁致伸缩模型计算铁心磁致伸缩形变的具体过程,通过与测量结果的比较,进一步分析了所提理论模型的有效性。研究表明,旋转磁化下电工钢片磁致伸缩具有滞后行为,该文从磁化机理角度提出的磁致伸缩模型可以有效地表征这种特性。     

考虑不同磁特性模型的感应电机铁心损耗分析

电机铁心损耗与铁心磁化方式及不同磁化条件下电工钢片的磁特性密切相关。该文研究了3种描述电工钢片交变磁化、交变旋转混合磁化的磁特性模型,即改进型 E&S模型、复数E&S模型和传统B-H曲线,给出了相应的损耗计算公式,并以一台三相感应电机为算例,从有限元数值计算和样机实验测试两方面对比分析了上述3种磁特性模型及其损耗计算的有效性。研究结果表明,只有在有限元分析过程中耦合同时能够描述电工钢片交变磁化和旋转磁化的矢量磁特性模型,才能较为准确地计算三相感应电机铁心损耗。     

基于PREISACH理论的电流互感器建模研究

提出了一种新型电流互感器（CT）数字化模型。该模型由CT电磁感应方程和基于Preisach理论的新型铁心磁化模型组成：基于Priesach理论的WIPING—OUT特性，提出了确定铁心运行所在磁化曲线的方法，并在新坐标系下分离Preisach函数的变量，得到了不同情况下铁心磁通密度的计算方法，由此建立了铁心磁化模型；提出了一种新的寻解算法，通过该算法将铁心磁化模型同CT电磁感应方程相耦合，建立了CT数字化模型。该模型只需极限磁滞回环下降支、一次电流和二次负荷等少量易被直接测得的参数，即可较准确地仿真铁心内部磁化过程，具有实现简便，仿真精度高等特点。采用文中CT模型对保护CT的饱和特性进行了仿真研究，仿真结果和实测数据的比较验证了模型的有效性。     

谐波激励下铁心等效磁路长度及接缝区损耗特性

为了研究谐波对变压器铁心等效磁路长度与接缝区域损耗的影响,文中基于完全按照电力变压器的标准设计和制作的叠片铁心模型,在不同谐波激励条件下,对铁心模型的等效磁路长度与接缝区域的损耗特性进行试验研究。研究表明:谐波阶次与谐波相位对铁心的磁路长度影响不是很大,在谐波条件下分析计算铁心的磁滞回环或磁化曲线时,可近似选择铁心的几何平均长度作为有效的磁路长度;不同谐波阶次与不同谐波相位激励下,铁心接缝区域比总损耗特性的变化规律大致相同:当磁通密度小于0.5 T时,接缝区的损耗近似为零;当磁通密度高于1 T时,接缝区的损耗出现明显的上升趋势。文中所用方法和所得结论对变压器产品的电磁分析和优化设计具有一定的指导意义。     

Development and practical application of fully split core for power transformers

In a three-phase, three-leg core of a core-type power transformer, the yokes are magnetically connected to all three phases so as to ease the flow of the magnetic flux (generally by means of lap joints of yokes and legs), and at the same time to smooth the magnetic flux between phase legs through yokes. It has generally been assumed that a split core with full separation at the center of the leg including yokes is unsuitable for use in power transformers owing to core losses, local heating, and noise resulting from the imbalance and distortion of magnetic flux, even though it can be used in distribution transformers with wound cores. But since the split core has many advantages from the manufacturing viewpoint, the magnetic characteristics of small core models were studied in detail. Studies with a full-scale 1500/3 MVA model transformer core indicate that the degradation of magnetic characteristics compares favorably with conventional cores.     

Effect of dimension ratio on the magnetic properties of tape-wound toroidal core with ac excitation

Tape-wound toroidal cores are used widely as magnetic devices of electronic equipment and instruments. In the design of equipment employing magnetic cores, it is necessary to know the relation between the magnetic properties of the core and the magnetic properties of the material. This paper describes the effect of the dimension ratio of the core on the magnetic properties for the sinusoidal flux waveform drive condition. In carrying out the analysis, a mode analysis in which the magnetization characteristics are approximated by a piecewise-linear curve is adopted. From the results obtained by the numerical analysis, local flux waveforms and exciting current waveforms of the core are shown. As a result, the relation between iron loss and magnetizing apparent power of the core and the dimension ratio is derived. These results were confirmed by experiments.     

基于辅助磁芯阻抗自适应调整的输电线路在线稳定取能方法

针对输电线路电流大范围波动导致在线取能装置能量溢出的问题,为保障取能需求提出了一种基于辅助磁芯阻抗自适应调整的输电线路在线稳定取能方法。通过增添辅助磁芯,构建取能支路和信号支路的多磁路模型来达到稳定取能的目的。基于母线电流、取能支路线圈电流和信号支路线圈电流之间的联系,在Matlab/Simulink仿真和试验平台上搭建了相应的取能模型。分别在不同电流、有无辅助磁芯两种工况下探究取能支路的运行效果,同时对成本、控制复杂度及可靠性进行分析。最后的仿真和试验结果表明,输电线路电流由30 A上升至100 A,取能负载输出电压仍能维持在稳定范围内,在无须额外供电模块的条件下也能保障取能负载输出电压,满足在线监测装置的供电需求。     

类比有限元法求解铁氧体电感器磁场特征参数

密绕线匝的铁氧体电感器磁场强度H可认为仅有环向分量,若选择H为自由度,则成轴对称场分布;加载环向电流的电感器选择矢量磁位A为自由度时也呈轴对称分布,该文推导了这两类磁场在各自自由度下满足的微分方程。当两种场具有相同的材料特性、形状及相似的边界条件时,即可通过后者类比求解前者的场分布,由此可以选择矢量磁位A为自由度条件下以轴对称的方式求解铁氧体密绕电感器的磁场分布及对应的磁场参数。以两种结构的铁氧体电感器为例,在计及寄生电容的条件下,建立电感器的R-L-C集中参数模型,由此得到仅含有电阻和电感可测量的串联模型。在10 MHz范围内,等效电阻、等效电感、等效相位角计算与实验取得了一致结果,验证了计算方法的正确性和结果的准确性,为该类电感器在电力电子及其相关领域的设计提供了一条理论分析的途径。     

基于三维磁网络法E型铁心横向磁场电机的设计与研究

该文首先在分析了横向磁场电机(TFM)其他几种结构的基础上，提出一种新型的TFM，其特点在于结构相对简单，从而可降低成本。然后，提出了TFM主要尺寸确定方法，并对三维等效磁网络法的基本原理做了简单阐述，运用该方法对一台TFM样机的电磁场进行了分析，对影响电机电磁转矩的几个主要参数进行了初步研究，提出了2相TFM减少自定位转矩影响的方法。     

树脂固化制度对非晶浸漆铁芯软磁性能的影响

将非晶Fe80Si9B11合金带材卷绕铁芯于663K保护气氛下保温90min,然后依照正交实验法进行浸漆固化处理,研究了浸漆铁芯的固化制度对其软磁性能的影响。试验结果表明,铁芯浸漆之后其软磁性能恶化,其中以固化温度影响最大,升温速率次之,固化时间影响最小。当以3K/min升温到393K并保温360min时,浸漆铁芯具有最优异的软磁性能,这主要与胶液固化收缩内应力有关。此时,1kHz/1T下损耗增高20.7%,10kHz/1V的单匝电感减小2.6%,磁感应强度B800(800A/m)下降7.1%。该研究优化了非晶铁芯的浸漆固化制度,对其工业批量生产具有指导作用。     

Stator‐core structure and winding technology for EPS motors

Electric power steering (EPS) motors must have the performance characteristics of precision machines. They should be compact and produce high power. Moreover, the loss torque and the change of loss torque should be as low as possible. In this study, dividing the stator core into small blocks and winding the coils densely on the blocks are shown to be effective techniques for achieving compact high‐power motors. We examined whether I‐shaped divided cores or T‐shaped divided cores were more suitable for EPS motors in terms of motor performance and production cost. We built two experimental motors, one with I‐shaped divided cores and the other with T‐shaped divided cores, and measured three important characteristics of EPS motors: output torque, loss torque, and loss torque change. The T‐type motor proved to have better performance for all three characteristics. Moreover, the productivity of the T‐type motor was shown to be higher than that of the I‐type motor, indicating that overall, T‐shaped divided cores are advantageous for the stators of EPS motors. Next, we considered a new winding method for the continuous winding of two T‐shaped cores in order to achieve a compact terminal connection board. The extending lines made by the new winding method do not extend beyond the coil end. Therefore, this method will contribute to reduction of the axial dimension of EPS motors. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 175(1): 35–42, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21085     

Demonstration of loss reduction effect of 66 kV‐classed 30 MVA three phase hybrid‐core transformer by trial manufacture

To realize larger‐capacity “Hybrid‐core transformer: HBT”, this research has assembled a 30‐MVA three‐phase trial HBT and evaluated the loss performances. The hybrid‐core consisting of the wound amorphous‐ and the stacked silicon steel‐cores, is expected having advantages of lower iron loss of the iron‐based amorphous material and the higher mechanical strength and saturation magnetic flux density of the silicon steels simultaneously. Three‐dimensional finite‐element method analysis revealed that the silicon steel core prevented over‐saturation of the amorphous core. The hybrid configuration enabled the design to have an approximately 10% higher magnetic flux density than configurations with only an amorphous core. We then assembled a prototype 30‐MVA three‐phase HBT designed on the basis of our investigation results. Operation tests demonstrated that the HBT has 62%‐reduced iron loss and 0.10%‐higher 50%‐loaded power efficiency from the conventional silicon steel core transformer.