气隙对电感磁芯内部磁场分布及电感的影响

开关电源的输出滤波电感中流过的电流比较大,磁芯容易出现饱和现象。为了解决这一问题,常用的方法是在电感磁芯中加开气隙,但加开气隙会对整个器件的性能产生影响。采用三维有限元方法对不同添加气隙方法对感性器件电感量的影响进行分析,得到了对应不同气隙量和匝数电感和磁芯内部磁感应强度分布,样品电感实测值与计算值对比,验证了仿真结果的正确性,为感性元件的工程设计和试验前预校正提供了一种新方法。     

高磁通密度铁粉芯的研发进展

综合评述了国外高磁通密度铁粉芯的性能,介绍了几种材料的制备技术,包括MgO绝缘膜及其铁粉芯的制备,耐高温树脂绝缘膜包覆铁粉芯的制备、Sr-B-P-O磷酸盐绝缘膜及其铁粉芯的制备,以及高密度成型的加热模腔润滑技术等.     

Leakage magnetic flux density in the vicinity of induction motor during operation

In this work, the low frequency electromagnetic flux density around induction motors is studied; the main objective is to provide safety regions for humans in the vicinity of these motors, especially in electrical vehicles, where high currents and hence high flux density emissions are expected. A new equivalent magnetic circuit which accounts for stray magnetic fields is developed. The analysis shows that the emission of the stray field in the radial directions depends on the permeability of the stator body as well as the ampere turn of the stator winding. Small values of stator body permeability may result in very high stray flux emissions at levels that may require shielding to protect passengers just above the motor. Relatively far away from the stator (e.g., 50 cm for the tested motors), the flux is normally of low level and may not represent an exposure threat.     

居民用电量的远程自动抄表

南昌市居民生活用电实行“一户一表”,是我局城网改造的一个重要组成部分。实行“一户一表”后 ,直供居民户数成倍增加 ,居民用电量抄收工作量明显加大。不规范抄表和抄表不到位等现象时有发生 ,管理难度加大。利用现代科技手段实现居民用电量远程抄表 ,不仅能够提高工作效率 ,减轻抄表劳动强度 ;对强化企业管理 ,适应电力市场新形势的需要也是一个有益的尝试。国内不少城市正试行远程自动抄表。目前 ,相似的远程数据通信手段主要有无线和有线两种 ,我们对这两种通信技术进行了比较 :( 1 )无线。　无线数据通信受气候、环境的影响很大。如果…     

基于智能电能表的居民需求响应协同策略

随着新能源大量接入,传统由发电跟踪负荷变化的运行模式面临挑战。需求响应是重要的调度资源,信息技术的发展提高了居民负荷的响应能力。在此背景下,负荷服务实体（LSE）通过电价机制协调用户的响应实现供需互动。首先,对家用电器设备的分类和建模得到响应电价的优化模型,建立了基于智能电表的家庭能源管理系统（HEMS）。其次,根据负荷服务实体的供电成本函数得到电价制定模型。以电价和响应功率作为互动信息协调不同用户的响应,进行迭代计算直到收敛,实现整体优化。考虑到用户优化会导致总成本振荡无法收敛,在优化目标函数中添加连续两次迭代间负荷变化的惩罚项。最后,通过算例仿真,分析了上述协同优化策略对LSE和用户的影响,验证了所提策略在平滑功率曲线和降低用户成本的效果。     

居民电能表集中抄表系统存在问题分析

居民电能表集中抄表系统是集计算机、数字通信等多项技术于一体的高新技术产品。它不是简单的单一产品,而是一项技术复杂的系统工程。全国试点很多,失败也很多,有些省投资几亿却没有发挥作     

RZG智能化抄表系统在居民住宅小区的应用

以RS485总线与ZigBee无线信道及GPRS通用分组无线网络的方式进行混合组网,构建成RZG智能化抄表系统,通过该系统实现了对电能表实时数据的采集、传输、预付费及在线监测电能表运行状况等功能。     

高饱和磁通密度低损耗MnZn铁氧体材料ZY90的开发

采用传统的氧化物陶瓷工艺制备高饱和磁通密度、低损耗锰锌软磁铁氧体材料ZY90,研究了主配方和CaCO3、Co2O3等掺杂对材料饱和磁通密度和功率损耗的影响。结果表明,主配方氧化铁含量在55.2mol%时,可以获得较高饱和磁通密度;适量的CaCO3掺入可使铁氧体晶粒均匀,晶粒边界变厚,形成一定厚度的高阻层,降低比损耗因子;添加适量的Co2O3可以使K1值有多个补偿点,提高电阻率,降低损耗;当CaCO3掺杂量为1000×10-6,Co2O3掺杂量为1500×10-6,饱和磁通密度与功率损耗表现最好。     

基于红外探测的新型热流密度传感器设计

目前爆炸场热毁伤效应越来越受到人们的重视,针对爆炸场恶劣的测试环境要求,设计了一种基于红外探测的新型热流密度传感器。该传感器利用其热敏元件与爆炸产物直接接触使热敏元件温度升高进而产生红外辐射,基于红外测温的原理得出热敏元件的温升情况,通过热传导数学模型理论间接得出环境中的入射热流密度。相比于传统的热流密度传感器而言,这种新型热流密度传感器响应时间快、测试范围广、测量精度高、能够较好地用于爆炸场热毁伤测试评定。     

管道漏磁内检测的管壁缺陷漏磁场解析模型

漏磁内检测技术是长输油气管道缺陷检测的主要手段,缺陷几何特征识别对管道安全运行评价具有重要意义。基于二维磁偶极子模型,建立管道内壁缺陷漏磁场空间分布的三维解析模型,对磁化方向垂直缺陷时磁荷产生漏磁场的变化规律进行研究;基于内壁解析模型,引入管壁退磁影响因子,对模型进行补偿,建立管道外壁缺陷漏磁场三维解析模型,得到了管道外壁不同缺陷漏磁场的分布特征。搭建漏磁检测实验平台,对所建模型有效性进行实验验证。结果表明,管壁对外壁缺陷漏磁场具有一定屏蔽作用,实验结果和理论分析具有很好的一致性,所建模型可有效描述管道内外壁缺陷漏磁场空间分布特性,对缺陷识别和定量评估具有一定工程指导意义。     

结构和材料参数对电磁炉锅具底部磁通密度的影响

电磁炉作为一种新型炊具,具有能效高、加热快、环境友好的优点。利用ANSYS有限元分析软件,通过研究电磁炉中软磁铁氧体磁条数量、相对磁导率、厚度以及磁条与锅具间距等因素对锅具中磁通密度分布的影响,提出高能效电磁炉在磁路设计方面应具备的条件。模拟计算结果表明,增加磁条数目、提高磁条材料磁导率时以及增加磁条厚度均可使锅具中磁通密度增加。此外,锅具与磁条间距离增大会导致锅具中磁通密度降低。     

Scattering of Dirac electrons by a random array of magnetic flux tubes

The scattering of two-dimensional (2D) massless electrons as presented in graphene in the presence of a random array of circular magnetic flux tubes is investigated. The momentum relaxation time and the Hall factor are obtained using optical theorem techniques for scattering. Electrons with energy close to those of the Landau levels of the flux tubes exhibit resonant scattering and have a long life-time to reside inside the magnetic flux tube. These resonances appear as sharp structures in the Hall factor and the magneto-resistance.     

基于模组电能表的居民侧智慧能源网关设计

居民侧用电量在社会总用电量中占有较大比重,但用电效率低。针对该问题,提出多用户智能电能表改进法和三相电能表改进法两种分路计量方法,并建立基于分时电价和分路计量的家庭负荷调控模型,以实现平衡电网负荷、减少电网容量投资的目的。设计了基于智慧能源网关的多表合采技术方案,并提出家庭用能情况展示与用能建议推送方法,研究了各类用能方式、用能场景下用能成本计算方法,实现以家庭用能成本最小为目标的家庭用能建议智能推送方式。     

核电站反应堆中子通量密度的一种预测控制方法

利用核电站反应堆中子动力学系统的单位阶跃响应数据，得到了该系统的非参数模型。提出了一种中子通量密度恒值问题的预测控制方法。与其于精确模型的控制方法相比，该方法不必苛求模型的具体形式，实时控制的计算量小、跟踪调节性能好、鲁棒性强、能消除不可测干扰。通过与状态反馈控制方法的仿真比较，验证了这种控制律的有效性和优越性。     

Electrical characteristics of a fully superconducting brushless generator equipped with a magnetic flux pump

The study of efficient excitation systems is important in order to enhance the potential of superconducting ac generators. We have fabricated a model machine for generating electricity with a brushless exciter system, which consists of a superconducting dynamo or “magnetic flux pump.” A fully superconducting generator in which both armature and field windings are made of superconductors has also been studied. The paper presents power output tests and calculated results on transients as well as the static electrical characteristics of a model machine equipped with a magnetic flux pump when operated as a fully superconducting brushless generator in persistent current mode. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 120 (3): 64–72, 1997     

An experimental study of the flux control characteristics of a magnetic fluid controlled by a parallel or orthogonal magnetic field

This paper presents experimental results of the flux control characteristic and the inductance control characteristic of magnetic fluid which is controlled by the permanent magnets. Two kinds of magnetic field, parallel and orthogonal, are discussed comparatively. The position between the magnetic fluid and the permanent magnet determines the magnetic field. The results are useful when employing magnetic fluid as a sensor or a control element.     

A brushless electric motor with a transverse magnetic flux and disk rotor

Brushless permanent magnet machines (BPMMs) have a greater efficiency and smaller overall dimensions than do other types of machines and are widely used in electric drives for various purposes. Two types of BPMMs are used in practice: BPMMs with a classical double-layer-distributed stator winding and BPMMs with a toothed-step stator winding. There exists another type of BPMM with a transverse magnetic flux (transverse flux motors, TFMs) which is being actively studied. In TFM electric motors, the magnetic lines of fluxes of the poles of rotor end perpendicular to the direction of rotor rotation. Stator windings in these machines are fabricated as rings coaxial with rotor, and the magnetic circuit of stator consists of separate fragments. Specialists assert electric TFMs have a higher specific power—the ratio between the output power and the mass of the machine—than the electric motors of other type. They are of interest, first and foremost, for electric drives without reducing gears. In most TFM, only a half of the poles of rotor are magnetically connected with circular phases of stator. In this work, the TFM design with disk rotor is described, in which the magnetic flux of all poles of rotor is coupled to the circular phases of stator. The stator magnetic circuit in this machine consists of P-like elements, and alternation of polarity of these elements is provided due to the change of their position. As a result, the magnetic flux coupled to the circular phase increases doubles, as do the machine torque and power. Some results of modeling of a three-phase electric motor are presented. The results were obtained using the Ansys Maxwell computer code, including a graph of the change of torque on the shaft of a machine under rotation of the rotor under conditions of sinusoidal currents in phases.