Diffusion Equations of the Electric Charges and Magnetic Flux

Innovative definitions of the electric and magnetic diffusivities through conducting mediums and innovative diffusion equations of the electric charges and magnetic flux are verified in this article. Such innovations depend on the analogy of the governing laws of diffusion of the thermal, electrical, and magnetic energies and newly defined natures of the electric charges and magnetic flux as energy, or as electromagnetic waves, that have electric and magnetic potentials. The introduced diffusion equations of the electric charges and magnetic flux involve Laplacian operator and the introduced diffusivities. Both equations are applied to determine the electric and magnetic fields in conductors as the heat diffusion equation which is applied to determine the thermal field in steady and unsteady heat diffusion conditions. The use of electric networks for experimental modeling of thermal networks represents sufficient proof of similarity of the diffusion equations of both fields. By analysis of the diffusion phenomena of the three considered modes of energy transfer;the rates of flow of these energies are found to be directly proportional to the gradient of their volumetric concentration, or density, and the proportionality constants in such relations are the diffusivity of each energy. Such analysis leads also to find proportionality relations between the potentials of such energies and their volumetric concentrations. Validity of the introduced diffusion equations is verified by correspondence their solutions to the measurement results of the electric and magnetic fields in microwave ovens.

Electromagnetic Performance Analysis of Variable Flux Memory Machines with Series-magnetic-circuit and Different Rotor Topologies

In this paper,the electromagnetic performance of variable flux memory(VFM)machines with series-magnetic-circuit is investigated and compared for different rotor topologies.Based on a V-type VFM machine,five topologies with different interior permanent magnet(IPM)arrangements are evolved and optimized under same constrains.Based on two-dimensional(2-D)finite element(FE)method,their electromagnetic performance at magnetization and demagnetization states is evaluated.It reveals that the iron bridge and rotor lamination region between constant PM(CPM)and variable PM(VPM)play an important role in torque density and flux regulation(FR)capabilities.Besides,the global efficiency can be improved in VFM machines by adjusting magnetization state(MS)under different operating conditions.

An Entropy Approach to the Natures of the Electric Charge and Magnetic Flux

As a result of investigating analytically and experimentally the interchangeability between thermal, electrical and magnetic energies, it is proved in the presented study that the electric and magnetic energies have an equivalent grade and nature as the thermal energy. So, the natural flow of electric charges and magnetic flux is associated also by increase of entropy of universe, similar to the heat, and has the same nature of waves as the electromagnetic heat radiation. Casting the Maxwell’s wave equation into an energy frame of reference that replaces the time in wave equations by entropy, it is possible to represent the electric charges and magnetic flux as electromagnetic waves of electric and magnetic potentials. Such results lead to modify exclusively the definition of the physical nature of the electric charge and magnetic flux which is unavailable in literature.

Energy states of the Hulthen plus Coulomb-like potential with position-dependent mass function in external magnetic fields

We need to solve a suitable exponential form of the position-dependent mass （PDM） Schr6dinger equation with a charged particle placed in the Hulthen plus Coulomb-like potential field and under the actions of the external magnetic and Aharonov-Bohm （AB） flux fields. The bound state energies and their corresponding wave functions are calculated for the spatially-dependent mass distribution function of interest in physics. A few plots of some numerical results with respect to the energy are shown.

Approximate energies and thermal properties of a position-dependent mass charged particle under external magnetic fields

We solve the Schrodinger equation with a position-dependent mass（PDM） charged particle interacted via the superposition of the Morse-plus-Coulomb potentials and is under the influence of external magnetic and Aharonov–Bohm（AB） flux fields. The nonrelativistic bound state energies together with their wave functions are calculated for two spatially-dependent mass distribution functions. We also study the thermal quantities of such a system. Further, the canonical formalism is used to compute various thermodynamic variables for second choosing mass by using the Gibbs formalism. We give plots for energy states as a function of various physical parameters. The behavior of the internal energy, specific heat, and entropy as functions of temperature and mass density parameter in the inverse-square mass case for different values of magnetic field are shown.

Numerical Analysis of Magnetic Force of Dry-Type Air-Core Reactor

This paper presents a coupled magnetic-circuit method for computing the magnetic force of air-core reactor under short-time current. The current and the magnetic flux density are computed first and then the magnetic force is obtained. Thus, the dynamic stability performance of air-core reactor can be analyzed at the design stage to reduce experimental cost and shorten the lead-time of product development.

Theoretical Maxwell's Equations, Gauge Field and Their Universality Based on One Conservation Law

The notion of the inner product of vectors is extended to tensors of different orders, which may replace the vector product usually. The essences of the differential and the codiffcrential forms are pointed out： they represent the tangent surface and the normal surface fluxes of a tensor, reslpetivcly. The definitions of the divergence and the curl of a 2D surface flux of a tensor arc obtained. Maxwell＇s equations, namely, the constraction law of field, which were usually established based on two conservation laws of electric charge and imaginary magnetic charge, are derived by the author only by using one conservation law （ mass or fluid flux quantity and so on） and the feature of central field （or its composition）. By the feature of central field （or its composition）, the curl of 2D flux is zero. Both universality of gauge field and the difficulty of magnetic monopole theory （ a magnetic monopole has no effect on electric current just like a couple hasing no effect on the sum of forces） axe presented： magnetic monopole has no the feature of magnet. Finally it is pointed out that the base of relation of mass and energy is already involved in Maxwell＇s equations.

Number-Phase Quantization Scheme for L-C Circuit

For a mesoscopic L-C circuit,besides the Louisell's quantization scheme in which electric charge q andelectric current I are respectively quantized as the coordinate operator Q and momentum operator P,in this paperwe propose a new quantization scheme in the context of number-phase quantization through the standard Lagrangianformalism.The comparison between this number-phase quantization with the Josephson junction's Cooper pair number-phase-difference quantization scheme is made.

Effects of external fields on a two-dimensional Klein-Gordon particle under pseudo-harmonic oscillator interaction

We study the effects of the perpendicular magnetic and Aharonov-Bohm （AB） flux fields on the energy levels of a two-dimensional （2D） Klein Gordon （KG） particle subjected to an equal scalar and vector pseudo-harmonic oscillator （PHO）. We calculate the exact energy eigenvalues and normalized wave functions in terms of chemical potential param- eter, magnetic field strength, AB flux field, and magnetic quantum number by means of the Nikiforov Uvarov （NU） method. The non-relativistic limit, PHO, and harmonic oscillator solutions in the existence and absence of external fields are also obtained.

基于径向气隙磁密和定子电流的永磁同步电机均匀退磁故障诊断研究

该文提出一种基于径向气隙磁密和定子电流的永磁同步电机均匀退磁故障诊断方法。首先,建立电机的d轴等效磁路模型,分析均匀退磁故障后径向气隙磁密的变化规律;然后,获取电机的径向气隙磁密和定子电流信号,对各极下径向气隙磁密幅值进行归一化处理,并绘制雷达图,根据雷达图和比较相同定子电流幅值下健康电机和故障电机的各极下径向气隙磁密幅值的平均值,来诊断均匀退磁故障;利用空载各极下径向气隙磁密幅值的平均值计算故障程度。最后,仿真和实验结果均验证所提均匀退磁故障诊断方法的有效性。

基于气隙磁密差信号峭度因子的永磁同步电机局部退磁故障诊断

该文提出一种新型基于气隙磁密信号差峭度因子的永磁同步电机局部退磁故障诊断方法。首先,建立永磁同步电机等效磁路模型,根据简化模型分析局部退磁故障后各极主磁路下径向气隙磁密的变化规律。然后,将预存健康电机空载状态下气隙磁密信号与测量的在线状态下气隙磁密信号作差并计算其峭度值,作为故障特征值。取健康电机空载状态下气隙磁密信号与不同工况下气隙磁密信号差峭度值的最大值作为参考值,根据故障特征值与参考值的大小诊断出局部退磁。最后,仿真和实验结果均验证提出的局部退磁故障诊断方法的有效性。

浅谈安培环路定理的使用

通过应用安培环路定理求解了有限长载流直导线的磁感应强度,说明了“有限长度”的数学条件和物理背景.从麦克斯韦方程的积分形式和微分形式,讨论了安培环路定理的使用场景,阐明了非对称电流密度分布情况下求解稳恒磁场的基本思想——边界条件确定磁场,并拓展至应用高斯定理求解非对称电荷密度分布静电场问题.

基于虚拟方波注入的五相永磁同步电机开路故障下直接转矩控制

在传统直接转矩控制(DTC)中,参考磁链往往是一个固定值,这将导致五相永磁同步电机(PMSM)在正常及容错情况下运行时效率不高。为解决该问题,该文提出一种基于虚拟方波注入的DTC(VSWI-DTC)策略。首先,建立五相PMSM在正常和开路故障情况下的数学模型,在同步旋转坐标系中推导出恒定转矩下电流幅值与定子磁链幅值的关系。其次,设计最优定子磁链探测器。通过向定子磁链幅值中注入虚拟方波信号,根据电流幅值的变化情况补偿定子磁链幅值,在线探寻最优定子磁链幅值。最后,与无差拍DTC相结合,实现电机高效率DTC运行。实验结果表明,所提策略不但能保持DTC良好的动态性能,抑制开路故障引起的转矩脉动,而且提高了电机在正常和开路故障情况下的效率。

三相变压器两侧绕组匝间短路电磁特性研究

为了研究变压器匝间短路时电流随匝数的变化规律,首先对变压器匝间短路时的电流进行了解析推导。然后,建立变压器匝间短路故障前后的等效电路,推导两侧电流随短路匝数变化的公式,并通过自检电阻的不同状态进行自我验证和推广应用。最后,采用商业软件Ansys对实际变压器进行正常运行及匝间短路时电流与磁场的仿真计算,与解析法电流公式对比,验证了解析公式及数值计算的准确性。研究结果可为变压器匝间短路的检测与分析提供参考。

多通道钢丝绳的漏磁检测信号融合方法

分析了现有钢丝绳漏磁检测系统中存在的损伤信号幅值较小、前端多个磁敏元件处理方式较为简单等问题,提出了一种钢丝绳漏磁检测系统中的多通道信号融合方法。首先从磁敏元件阵列的角度出发,提出了多种磁敏元件阵列方式;其次从信号处理模拟电路的角度出发,设计了多通道信号融合硬件电路;最后,针对钢丝绳进行了实际测试,验证了此方法的可行性。

NiMnGa磁控形状记忆合金纵振式换能器

为实现低频、小尺寸水下声源,利用具有大应变、快速响应和高能量密度等优势的NiMnGa合金为驱动元件设计了水声换能器。基于NiMnGa合金变形原理,建立了NiMnGa纵振式换能器物理模型,推导了等效电路。通过有限元法,实现了NiMnGa纵振式换能器电磁-机械-声的多物理场耦合仿真,用于预测换能器的水下声学性能。制作了小型NiMnGa纵振式换能器样机,并在水中测试了500~800 Hz频带内的声源级。实验结果表明,换能器样机辐射面直径为8 mm,水中谐振频率为700 Hz,最大声源级为115.5 dB。

基于磁场分割法的EE型电感器磁路参数计算

开关电源电感器设计中,磁路参数的计算具有重要意义。首先,针对EE型磁芯中柱开气隙的电感器,结合有限元仿真,通过理论分析,利用磁场分割的方法将总磁通量分为7个等效磁通,提出无效匝数的概念,在充分考虑扩散磁通、旁路磁通及磁芯磁通分布不均匀影响的基础上,求得主气隙磁导等效面积的解析表达式,根据等效磁路模型,从而求得电感系数AL的解析表达式。提出磁密分布不均匀系数的概念,根据单位电流最大磁通密度,求得饱和电流IA的解析表达式。然后,采用编制Excel表的方式对磁路参数进行精确计算。最后,通过实验测量,验证了所建公式的准确性,可为设计人员提供有益参考。

新型Halbach阵列盘式永磁电机的磁场解析

基于印制电路板(PCB)技术的盘式永磁电机(AFPMM)提出一种新型Halbach阵列的转子结构,该阵列结构简单、易于优化。运用矢量磁位法对新型转子产生的空载气隙磁密进行解析推导,获得关于气隙磁场的数学模型。基于该模型,保持永磁体总用量不变,以永磁体极弧系数比和径向长度比作为优化变量,气隙磁密基波幅值和谐波畸变率作为优化目标,确立最优转子结构参数。三维有限元仿真结果表明,解析法所得的气隙磁密波形与有限元法基本一致,验证了所提出解析模型的合理性。与传统Halbach阵列相比,新型Halbach阵列气隙磁密基波幅值提升了10.3%,同时谐波畸变率由19.8%降至4.8%,优化效果明显,可以有效降低高频工况下电机的涡流损耗、提升电机效率。最后制造一台样机进行相关实验测试,验证了解析和仿真分析的正确性,对PCB定子AFPMM的设计具有一定参考价值。

直线型磁通切换电机特性分析的时步有限元模型

针对直线型双边磁通切换永磁电机(DLFSPM)结构相对复杂,现阶段运行特性研究不充分的问题,以时步有限元为工具,建立了一种研究DLFSPM运行特性的场路耦合分析模型。阐述了DLFSPM电动运行原理,并推导出ABC坐标系下的运行特性方程。为解决直线电机仿真环境下的开域处理问题,建立圆弧形电机仿真拓扑,以一台额定输出电磁推力为400 N的DLFSPM样机为例,得到可以同时考虑DLFSPM内部磁场和外电路特性的场路耦合时步有限元模型。最后,利用该时步有限元分析模型研究了其空载特性和力角特性,仿真与实测的相关对比曲线结果表明二者吻合较好,说明该模型具有良好的计算精度,进一步验证了其正确性和有效性。