考虑附加涡流损失的超磁致伸缩执行器动态模型

超磁致伸缩执行器在高频下工作时,能量损失不仅包括磁滞损失、Terfenol-D棒涡流损失,还包括Terfenol-D棒附加涡流损失。该文考虑到执行器的惯性、阻尼、Terfenol-D棒涡流损失及附加涡流损失,建立了超磁致伸缩执行器的动态模型。其磁滞特性由Berqvist和Engdahl磁滞模型来描述,材料非线性由输入到模型静态实验数据体现。模型求解使用有限差分方法,在Matlab/Simulink中建立相应模型仿真结构框图。对执行器不同工作频率情况进行模型的仿真计算,并与实验结果对比,发现模型与实验吻合较好。表明所建立动态模型能较好地描述执行器输出位移与驱动电流之间的关系。该模型对优化设计超磁致伸缩执行器有指导意义。     

Magnetic Material Test by Waveform Sampling

The evaluation of magnetic steel for electric motor applications has been most effectively done with ring samples rather than Epstein samples. However, the tests required skilled technicians and considerable time to wind magnetizing and excitation coils and to compute required magnetic variables. A test system is presented that is fast and requires no special skills. Yet the controls and calculations required by standard magnetic testing are performed. A simple three-turn fixture replaces toroidal windings, and the necessary flux waveform control is achieved by a power amplifier and feedback control. Calculations and the test report are supplied by a microcomputer that also replaces meters by data sampling. The tester can also be used to evaluate the yokes of stator cores, and losses can be separated into hysteresis and eddy current by the two-frequency method.     

Modeling of hysteresis and power losses in transformer laminations

In this paper, a method for the representation of hysteresis and power losses in the laminations of power transformers is proposed. The developed model is based on data supplied from steel manufacturer and able to predict hysteresis and eddy current losses.     

高压自耦变压器的涡流损耗计算与屏蔽措施

为应对大型电力变压器漏磁场及杂散损耗问题,采用三维非线性涡流场有限元分析方法,以1台高压自耦变压器为研究对象,引入B-H曲线来描述非线性材料的磁特性,对变压器结构件进行了漏磁场及涡流损耗计算。采用屏蔽措施之前,油箱及夹件等结构件涡流损耗及涡流损耗密度较大,容易引起局部过热问题并且影响变压器正常运行。通过进一步分析,给出了油箱磁屏蔽、夹件L型磁屏蔽和肺叶式磁屏蔽等降低杂散损耗的措施,以及多种屏蔽形式对漏磁场及结构件涡流损耗的影响。结果表明对电力变压器油箱、夹件等结构件采取合理的磁屏蔽措施能够有效地降低杂散损耗并消除热点,不同屏蔽形式对其周围结构件涡流损耗及漏磁场具有不同影响。     

Current Transformer Model

This paper presents a current-transformer (CT) model that is useful for low-frequency applications. To describe the iron-core magnetic behavior, a hysteresis model is proposed, which is able to generate minor asymmetric loops and remanent flux. The effects of classic eddy current losses and anomalous losses are represented by linear and nonlinear resistors, respectively. The obtained results are compared with those calculated by the Preisach's model and measured in the laboratory. This model may be applied in power system protection studies, as it is the case of numeric correction of distorted secondary currents in current transformers (CTs)     

Magnetic Circuit Model Considering Magnetic Hysteresis

Quantitative estimation of core loss considering magnetic hysteresis property is strongly required to develop high‐efficient electrical machines. This paper presents a novel magnetic circuit model considering magnetic hysteresis. In the proposed model, dc hysteresis loss is calculated by the Landau–Lifshitz–Gilbert (LLG) equation, while classical and anomalous eddy current losses are calculated in the magnetic circuit. It is demonstrated that the hysteresis loop under PWM wave excitation can be expressed by the proposed model. The validity and effectiveness of the method are proved by comparing with measured values.     

基于对偶性原理的三相多芯柱变压器暂态模型

提出了一种基于对偶性原理的三相多芯柱变压器暂态模型；通过分析三相多芯柱变压器磁路模型并应用对偶性原理，建立了考虑电路与磁路耦合的变压器暂态计算模型，采用Jiles-Atherton铁磁磁滞模型来描述铁心模块的饱和以及磁滞效应，而涡流和杂散损耗用一个等值电阻替代，零序磁通用一个线性电感以及反映其涡流损耗的电阻代替；该模型可以计算分析直流偏磁和空载合闸等情况下变压器励磁电流以及铁心磁通等电气参数；算例分析结果与实验结果的对比证明了该模型的准确性。     

大截面电力电缆固定金具三维涡流场有限元分析

文中建立了大截面电缆固定金具的三维涡流场数学模型,考虑初始条件和边界条件,利用有限元法分别研究了缆芯电流、金具材料电导率以及金具厚度对金具涡流损耗的影响。计算结果表明,金具涡流损耗均随电流、电导率以及厚度的增加而增大。当电流较大时,金具涡流损耗变化较快;当电导率较大时,反而金具涡流损耗变化趋于平缓;金具涡流损耗随厚度的变化呈线性关系。文中提出选用不锈钢作为金具材料可以有效地降低金具中所产生的涡流损耗。     

Method for calculating iron loss for inductor motors

A method for calculating iron loss in switched-reluctance motors is given. It is necessary to separate the elements of the magnetic system of an electric motor in order to calculate the magnetic flux density according to the turning angle of the rotor. Then, calculations of losses due to hysteresis and eddy current are conducted. The described method can be applied for the verification and design of inductor motors.     

基于涡流损耗分析的金属顶管电缆沟优化仿真设计

高压电力电缆设计一直是电力设计的重要内容。随着电网建设水平的提升,电缆沟涡流损耗导致电能浪费并影响电缆寿命的问题越来越突出,因此文中以降低金属顶管电缆沟涡流损耗为优化设计目标,提出了一种新型的电缆沟设计。针对三相多回路的金属顶管电缆沟,分析研究发现:影响其涡流损耗的主要因素包括电缆相位的排列方式、顶管厚度和电缆距离。通过用Ansoft Maxwell进行仿真试验,在不同的电缆相位排列、顶管厚度及电缆距离条件下,模拟顶管涡流损耗的情况,再利用有限元法对电缆沟结构进行优化计算,获得新型电缆沟设计。试验结果证明了该设计能够有效降低涡流损耗。     

特高压特大容量变压器三维涡流场计算和防止局部过热技术的研究

对特高压变压器四种电屏蔽和磁屏蔽的组合方案进行了三维漏磁场有限元分析,研究了涡流损耗和磁滞损耗的计算方法,并列举了计算实例.     

Relation Between Firing Conditions Grain Boundary Structure and Magnetic Properties in Polycrystalline MnZn-Ferrites

The influence of the firing conditions on the nanoscale structure of the grain boundaries and on the magnetic properties of polycrystalline MnZn-ferrites is investigated, on specimens of nearly identical microstructures. High oxygen partial pressures favor accumulation of impurity ions at the triple points. Under appropriate oxygen pressures homogeneous accumulation of impurities along the grain boundaries may occur, revealing therefore chemically pure grains and low hysteresis losses; simultaneously an increase of the grain boundary resistivity occurs that results to low eddy current losses. Managing the raw material impurity cations towards controlled grain boundary structures leads to the synthesis of MnZn-ferrites with power losses similar to those achieved when high purity raw materials are used together with externally introduced additives.     

MoO3添加对高频MnZn功率铁氧体性能的影响

采用陶瓷工艺制备高频MnZn功率铁氧体材料,研究了MoO3添加对材料微结构和磁性能的影响。用X射线衍射仪(XRD)、扫描电子显微镜(SEM)表征材料结构,用B-H分析仪测试材料磁性能,并对材料功率损耗进行分离。结果表明,适量添加MoO3可以有效改善材料的微观结构,提高致密度,提高材料饱和磁通密度和起始磁导率,降低功率损耗。功耗分离后发现,随着MoO3添加量的增加,磁滞损耗比例下降,涡流损耗所占比例上升。最佳MoO3添加量为0.01 wt%,获得低功耗的MnZn功率铁氧体,100℃、500kHz、50mT条件下功耗为86 kW/m3,起始磁导率约为1928,25℃下的饱和磁通密度为513 mT。     

直线Halbach磁体用于磁浮列车涡流制动的研究

磁浮列车采用涡流制动摆脱了机械制动中粘着系数对制动性能的制约.电磁涡流制动需要电能供应,存在电能损耗.永磁涡流制动由于不需供电故效率高.永磁Halbach磁体磁感应强度大于普通永磁磁体,且Halbach磁体具有自屏蔽性能,一侧拥有强磁场,另一侧磁场几乎为零.直线Halbach磁体用于磁浮列车涡流制动的研究,采用解析的方法分析其制动过程中的电磁机理,推导出涡流制动力方程.设计了一套实验系统,对制动力方程进行了验证,并对实验结果进行了分析.     

Radial flux type hysteresis motor with rotor ring of copper-sprayed surface layer

This paper describes a new form of radial flux type hysteresis motor having large output, high efficiency, and high power factor. The rotor has a copper-sprayed surface layer on the rotor ring, which is made of Fe-Cr-Co magnet steel and has magnetic anisotropy and slits. The new configuration has two features. First, it is designed to give a combined hysteresis and reluctance-motor action effectively, particularly at a synchronous speed. Second, it is designed to give a combined hysteresis torque and large torque due to eddy current in asynchronous conditions, particularly at starting. To analyze motor performance at synchronous and asynchronous operations, the finite-element method is used. In this paper, magnetic hysteresis is considered by using complex permeability. The agreement between predicted and measured values of motor performance characteristics is good.     

轴向磁场电机永磁体空载涡流损耗减小方法对比研究

减少轴向磁场电机永磁体空载涡流损耗的方法主要有：减小定子槽开口宽度、增大气隙长度、永磁体分块、使用屏蔽层和磁性槽楔等。基于轴向磁场电机的简化二维分析模型,分析了减小定子槽开口宽度和增大气隙长度、使用屏蔽层和磁性槽楔降低空载涡流损耗的效果。通过三维电磁场仿真,研究了永磁体不同分块方式对减少空载涡流损耗的效果。研究结果表明,减小定子槽开口宽度的效果最佳;虽然增加气隙长度可以显著减小涡流损耗,但永磁体用量迅速增加;永磁体分块减小涡流效果较好,且周向分块方式最好;屏蔽层起反作用;使用分段磁性槽楔效果比减小定子槽开口宽度稍微差一点,但加工难度要低些。     

变压器箱体涡流损耗的三维有限元分析

建立了电力变压器漏磁场及箱体涡流损耗的计算模型,计算了变压器箱体的涡流损耗分布,提出了减少箱体涡流损耗的电磁屏蔽和磁屏蔽方法.     

用于电机损耗精细化分析的分段变系数铁耗计算模型

提出一种用于电机损耗精细化分析的分段变系数铁耗计算模型,该模型以经典Bertotti三项常系数铁耗模型为基础,引入涡流损耗附加磁通密度高次项及磁滞损耗附加磁通密度低次项,用于考虑磁路饱和导致涡流损耗增加及谐波磁场引起局部磁滞损耗增加的现象,同时,该模型中主要系数均随磁通密度幅值和频率变化,能很好地反映基波及谐波磁场对铁耗的影响,并对磁滞、涡流及异常损耗进行准确分离,实现铁耗精细化分析。为了验证该文所提模型的有效性及准确性,以Y132S-4、5.5k W和YX3-250M-4、55 k W两台感应电机为例,利用文中模型与经典Bertotti三项常系数模型对两台电机在不同电压下的空载铁耗进行实测和计算对比,结果表明该文所提模型在较宽范围内与实测值吻合程度较高。     

MnZn铁氧体功率损耗特性研究

采用固相反应法制备了Zn0.23Mn0.70Fe2.07O4功率铁氧体材料.研究了材料的静态磁参数和功率损耗;并在100kHz、200mT下对MnZn铁氧体材料的损耗进行了分离.结果表明,试样的Ⅱ峰在80℃左右,与磁滞损耗Ph极小值对应温度一致.材料的损耗特性随温度变化很大,在常温下,磁滞损耗Ph占了材料总损耗的大部分...     

双标量磁位的表面阻抗法

提出双标量磁位的表面阻杭法，以计算含有钢板的三维磁场分布和钢板涡流损耗。文中在钢板周围采用全标量磁位处理阻抗边界条件，而在源电流区域采用简化标量磁位，并应用磁余能量方法，引入等效虚拟磁性材料处理钢板的非线性问题。将本方法应用于ＴＥＡＭ问题２１模型，计算结果与实测结果相吻合。