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在脉冲功率领域,许多器件都需要使用磁芯,如脉冲变压器、磁开关、脉冲叠加器、感应加速腔等,磁芯的主要作用之一是增加回路的电感量,因此含磁芯回路电感量的计算是判断该磁芯是否适用于该环境的决定性依据,也是对线路进行准确模拟的前提。磁性材料在不同波形的励磁场下对应着不同的磁导率变化,而线圈的电感量与线圈中磁芯的磁导率成正比,因此,含磁芯线圈的电感在实际使用中必然是一个与励磁过程相关的动态值。 相似文献
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感应脉冲加速器的磁芯通常为铁氧体或非晶材料,而感应腔磁芯在工作脉冲下的磁性能是决定感应加速脉冲波形好坏的重要因素。搭建了低压多脉冲实验平台对铁氧体和非晶小磁环分别进行MHz重复频率的多脉冲励磁,对励磁线圈上的电压电流波形进行监测,绘制了多脉冲励磁下磁环的磁化曲线,并结合含磁芯线圈动态电感量的递推公式计算出磁环在多脉冲励磁过程中磁导率的变化曲线;在高压三脉冲实验平台上对铁氧体磁芯和非晶磁芯实验感应腔进行了高压三脉冲实验,得到的磁芯多脉冲磁化规律与低压实验的结果一致。最后对两种磁环在多脉冲励磁下的磁性能差异进行了对比分析。 相似文献
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Mini-LIA为MHz重复频率双脉冲电子直线感应加速器,由双脉冲功率系统、热阴极电子枪注入器及金属玻璃磁芯感应加速腔等组成。在此平台的实验获得了数百ns间隔(即MHz重复频率)的双脉冲高压,每个脉冲幅值达到80 kV,脉冲半高全宽为80 ns;在感应腔加速间隙处测得双脉冲加速电场;在加速器出口处测量得到流强约1.1 A的双脉冲电子束流。实验结果表明:利用硅堆隔离汇流装置可实现MHz重复频率的双脉冲高压,金属玻璃磁芯感应加速腔和六硼化镧热阴极电子枪均适合MHz重复频率双脉冲工作方式。 相似文献
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磁芯是直线变压器驱动源(LTD)的关键部件之一,起着初、次级能量传递和次级电压感应叠加的作用,磁芯的能量传递效率对LTD系统的效率、体积和重量影响显著。对LTD系统中影响磁芯能量传递效率的原因进行了初步的分析,并利用Pspice软件的非线性磁芯模型对磁芯的工作过程和损耗进行了模拟计算,最后对LTD磁芯的能量传递效率进行了初步的实验研究,在工作电压为20 kV时、脉宽约220 ns时,在2.8 Ω负载上获得了大于60%的能量传递效率。 相似文献
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P. J. Gaede 《Zeitschrift für Physik A Hadrons and Nuclei》1972,255(1):40-58
A hydrogen arc with a fixed lower and a movable upper end abruptly changes from its straight static form into a rotating conical helix when a critical current is exceeded. The chances of its winding becoming left or right-hand are equal if the earth magnetic field is compensated. A helix with a left winding, however, is always turning clockwise, a helix with a right winding counter-clockwise if looking axially in the direction of the expanding helical arc. The frequency of the rotation depends only on the current strength and is explained by the balance of the driving Lorentz forces due to the intrinsic magnetic field of the entire electrical circuit on one hand and the friction of the moving arc with its environment on the other. A corresponding model theory applied to measurements on a wall-stabilized H2-Arc with 10–15 A in a quartz tube of 10 mm radius yields a reasonable arc diameter of 2.23 mm. The observed independence of the rotation frequency on the length of the arc can be derived from the balance equations as well. By superimposing an external axial magnetic field to the rotating arc its rotation frequency and simultaneously its expansion increase if the external field is parallel to the intrinsic one and viceversa. The experimental results are in full agreement with calculations based upon the model including the effect of the external field as an additional independent variable. 相似文献
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Cosmic vortons are closed loops of superconducting cosmic strings carrying current and charge. Despite a large number of studies the existence and stability of cosmic vorton solutions is still an open problem. Numerical simulations of the non-linear field theory are difficult to perform in (3+1)-dimensions, due to the existence of multiple length and time scales. In this paper we study a (2+1)-dimensional analogue of cosmic vortons, which we refer to as kinky vortons, where the cosmic string is replaced by a kink string. Many of the expected qualitative aspects of cosmic vortons transfer to kinky vortons, with the advantage that several approximations used in the study of cosmic vortons can be replaced by exact results. Furthermore, the numerical study of kinky vortons requires less computational resources than cosmic vortons, so a number of issues can be addressed in some depth. The radius of the kinky vorton is determined as a function of the charge and winding number, and it is shown that the chiral limit is a repulsive fixed point. Stability to both axial and non-axial perturbations is demonstrated in the electric and chiral regimes, though surpringly long lived ringing modes are observed. Kinky vortons which are too magnetic are shown to suffer from a pinching instability, which results in a reduction in the winding number and can convert magnetic into electric solutions. 相似文献
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电子真空回旋器件是一种对磁场精度要求较高的微波源装置, 一般采用超导磁体提供磁场环境. 超导磁体的应用中, 磁场分布的实现是超导磁体设计的核心问题. 提供回旋器件磁场的高温超导磁体包含较复杂的磁体绕组, 为了解决此类设计计算问题, 本文提出了一种包含设计区域约束的线性优化方法进行回旋器件高温超导绕组的设计优化, 通过分步的约束和线性优化计算, 可得到同时满足设计要求和绕组可实现的设计磁场电流分布设计. 计算实例的结果给出了一个提供磁场强度1 .3 Tesla, 长度285 mm 的均匀磁场区域, 同时满足多位置的磁场要求, 设计结果与要求一致度较好, 精度满足应用需求. 该计算方法是一种可适用于较复杂磁场要求和超导绕组结构的设计优化方法. 相似文献
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Calculation and analysis of unbalanced magnetic pulls of different stator winding setups in static eccentric induction motor 下载免费PDF全文
In large-scale electric machines, unbalanced magnetic pull(UMP) caused by eccentricity usually results in stator-rotor rub, so it is necessary to investigate the amplitude and the influencing factors. This paper takes the squirrel-cage induction motor as an example. A magnetic loop model of an induction motor is established by an analytical method. The impact of stator winding setup(parallel branch and pole pairs) on each magnetomotive force(MMF) and unbalanced magnetic pull is analyzed. Using the finite element simulation method, the spatial and time distribution of flux density of the rotor outer circle under static eccentricity is obtained, and the unbalanced magnetic pull calculation caused by static eccentricity is completed. The conclusion of the influence of stator winding on the size of unbalanced magnetic pull provides reliable gist for motor noise and vibration analysis, and especially provides an important reference for large induction motor design. 相似文献
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分析了线圈杂散参数对高频下复磁导率测量的影响,指出绕组电阻、寄生电容及漏感会导致传统复磁导率测量方法在高频下误差增大。在此基础上提出了使用单匝全包结构进行复磁导率宽带测量的方法,该方法适用于400 MHz以下频率的复磁导率测量。介绍了复磁导率的常见模型,并分别使用Levy法及有理函数迭代逼近法(IRFA)进行模型参数提取,分析了两种算法的优缺点及应用范围。应用推荐复磁导率测量方法对三种磁性材料进行了复磁导率的测量和建模,结果表明,使用推荐的复磁导率测量方法及数据提取算法,可以较好地实现对磁性材料的小信号建模。 相似文献
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Adoum Kriga Désiré Allassem Malloum Soultan Jean-Pierre Chatelon Ali Siblini Bruno Allard Jean Jacques Rousseau 《Journal of magnetism and magnetic materials》2012
The paper details the characterization of thin magnetic materials layers, particularly soft materials, with respect to their behaviour in frequency (from 10 MHz to 1 GHz). The proposed method is suitable for any soft but insulating magnetic material; Yttrium Iron Garnet (YIG) is used as an example. The principle is based on a comparison between simulations for different values of the permeability and measurement values versus frequency of planar inductor structures; an experimental validation is proposed as well. Thin magnetic material is first deposited on an alumina substrate using RF sputtering technique; a planar spiral winding of copper is then deposited on the magnetic material by the same technique. The effective permeability versus frequency is obtained by comparing two samples of spiral windings with and without magnetic material. Network analyser measurements on samples of various geometrical dimensions and of different thicknesses are necessary to determine the effective magnetic permeability; we have obtained a relative effective permeability of about 30 for seven turns spiral inductor of a 17 μm YIG film. 相似文献
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Transient vibration phenomena in deep mine hoisting cables. Part 1: Mathematical model 总被引:1,自引:0,他引:1
The classical moving co-ordinate frame approach and Hamilton's principle are employed to derive a distributed-parameter mathematical model to investigate the dynamic behaviour of deep mine hoisting cables. This model describes the coupled lateral-longitudinal dynamic response of the cables in terms of non-linear partial differential equations that accommodate the non-stationary nature of the system. Subsequently, the Rayleigh-Ritz procedure is applied to formulate a discrete mathematical model. Consequently, a system of non-linear non-stationary coupled second order ordinary differential equations arises to govern the temporal behaviour of the cable system. This discrete model with quadratic and cubic non-linear terms describes the modal interactions between lateral oscillations of the catenary cable and longitudinal oscillations of the vertical rope. It is shown that the response of the catenary-vertical rope system may feature a number of resonance phenomena, including external, parametric and autoparametric resonances. The parameters of a typical deep mine winder are used to identify the depth locations of the resonance regions during the ascending cycles with various winding velocities. 相似文献
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The non-linear relaxational properties of a water-based magnetic fluid are investigated by means of measuring the frequency dependent complex susceptibility, χ(ω) in the presence of an external potential. The results obtained are discussed in terms of the magnetic analogue of the Coffey and Paranjape model as modified by Déjardin. The loss processes in the magnetic fluid in the non-linear region are investigated in the context of the loss tangent, tan(δ), and the power dissipation per unit volume. These measurements are of importance because of the continuing interest in the clinical applications of magnetic fluids, where large alternating magnetic fields can be applied to magnetic fluids to induce loss processes and heating effects, often driving the magnetic fluid into the non-linear region of magnetisation. We evaluate the increment of the susceptibility, Δχ, due to the non-linear response, through measurement of χ(ω), and extend this formulism to the non-linear increment of the loss tangent, Δ tan(δ) and the increment of the heating rate, ΔUheat. 相似文献
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现有的“E”型平衡电枢等效磁路模型仿真研究通常不考虑金属外壳磁阻带来的影响。为了解决平衡电枢换能器中因金属外壳和平衡电枢紧密接触带来的非线性磁阻问题,在现有的平衡电枢换能器等效磁路模型上加入了外壳磁阻影响。分析等效磁路模型磁通部分和力学部分的状态空间方程在不同参数条件下的仿真结果,总结不同参数对该模型阻抗和振膜位移的影响情况。通过仿真对比,外壳磁阻对平衡电枢换能器位移频率响应曲线的影响为1~3 dB。对于组装后包含金属外壳的平衡电枢耳机、助听器产品降低频率响应曲线偏差具有一定的指导意义。 相似文献
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Wentao Liu Federico Casanova Bernhard Blümich Donglin Zu 《Applied magnetic resonance》2012,42(1):101-112
The main magnetic fields of mobile nuclear magnetic resonance (NMR) magnets differ from those of conventional NMR and magnetic
resonance imaging (MRI) magnets. In the Halbach magnet, the main field B
0 is perpendicular to the longitudinal axis, the symmetry of the current distribution with respect to the symmetry of the magnetic
field differs from that in conventional target-field applications, and the current distribution on the coil surface cannot
be expressed in terms of periodic basis functions. To obtain the winding pattern of the coil, an efficacious target-field
approach. The surface of a coil is divided into small discrete elements, where each element is represented by a magnetic dipole.
From the stream function of the elements, the resultant magnetic field is calculated. The optimization strategy follows an
objective function defined by the power dissipation or efficiency of the coil. This leads to the optimum stream function on
the coil surface, whose contour lines define the winding patterns of the coil. This paper shows winding patterns designed
of shim coils for Halbach magnet and illustrates the craft of a shim coil using flexible printed circuit board. The performance
of the coils is verified by simulating the fields they produce over the sensitive volume. 相似文献