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.

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.

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.

Direct Torque Control System and Sensorless Technique of Permanent Magnet Synchronous Motor

The direct torque control theory has achieved great success in the control ofinduction motors. However, in the DTC drive system of Permanent Magnet Synchronous Machine (PMSM)proposed a few years ago, there are many basic theoretical problems that must be clarified. Thispaper describes an investigation about the effect of the zero voltage space vectors in the DTCsystem of PMSM and points out that if using the zero voltage space vectors rationally, not only canthe DTC system be driven successfully but also the torque ripple is reduced and the performance ofthe system is improved. This paper also studies the sensorless technique in the DTC system of PMSMand configures the DTC system of PMSM with sensorless technique including zero voltage spacevectors. Numerical simulations and experimental tests have proved the theory correct. In thecondition of sensor-less, the DTC system of PMSM is wide-rangely speed adjusting, and the ratio ofspeed adjustment is 1: 100.

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.

新型混合励磁爪极电机Ansoft 3D仿真分析

针对现阶段爪极电机的效率低、电机空间利用率低和易磁饱和等问题,根据爪极电机的相关结构,提出一种利用电机端部空间实现混合励磁的新型电机,使用Ansoft软件构建电机的三维仿真模型,并对电机的磁场性能进行仿真分析.对比了新型爪极电机与传统爪极电机空载状态下的磁密和磁链特性,同时分析了新型爪极电机的齿槽转矩特性.结果表明,新型爪极电机具有更高的磁密与磁链特性,同时还具有更不易磁饱和特性.此外新型爪极电机具有较小的齿槽转矩,可以应用到驱动电机领域.

考虑磁链变化率的永磁同步电机失磁故障复合容错控制

针对永磁同步电机(PMSM)失磁故障中磁链变化较快,近似认为磁链变化率为0会导致传统PMSM失磁容错控制方法性能受限的问题,本文提出一种基于智能比例积分微分的无模型超螺旋滑模复合容错控制(iPID-MFSTSMC)方法。首先,构建考虑永磁体磁链变化量的PMSM失磁故障数学模型,根据这一模型设计了磁链滑模观测器,实现了对于磁链及其变化率的观测。此外,针对快速变化的负载转矩设计了负载转矩导数滑模观测器。然后,基于磁链及其变化率、负载转矩导数的观测,设计了iPID无模型容错控制方法,该方法采用超螺旋滑模算法对观测误差及其他扰动进行抑制,改善了动态性能且降低了控制器参数的设计难度。利用Lyapunov稳定性定理证明了所设计容错控制方法的稳定性,并给出了参数的设计条件。最后,在磁链以及负载转矩快速变化工况下,通过仿真和实验分析表明,该方法可以有效减少系统抖振并降低超调量。

基于磁链相移原理的不对称交替极永磁辅助同步磁阻电机设计与分析

传统永磁辅助同步磁阻电机(PMaSynRM)无法充分利用永磁转矩和磁阻转矩,该文提出一种新型不对称交替极永磁辅助同步磁阻电机(ACP-PMaSynRM)。基于永磁磁链相移原理,将交替极永磁阵列、不对称磁极和磁障相结合,实现永磁转矩和磁阻转矩的最大值在相同电流相位下叠加,不但提高了永磁转矩和磁阻转矩的利用率,增强了电机输出转矩能力,而且减少了永磁体用量。采用有限元法对比分析了传统和新型ACP-PMaSynRM的电磁性能,验证了所提电机拓扑的可行性。最后,制造了一台48槽14极样机并对其进行了实验验证。

船舶永磁同步推进电机的优化I/f起动控制方法

为解决高转矩与高转动惯量的船舶推进电机在开环I/f控制中转速和转矩波动大、电机易失步、效率低的问题,提出一种I/f控制改进方法。通过建立转矩角观测器,调节给定电流矢量的幅值,使其跟随负载转矩变化,提高系统鲁棒性。同时,将电机运行状态推进至接近最大转矩电流比状态,提高电机的运行效率;通过瞬时有功功率调节电流矢量的角速度,降低电磁转矩波动,加快电机的转速收敛过程。最后,在Matlab/Simulink中进行仿真实验,实验结果表明该方法可以显著提高推进电机运行效率和稳定性。

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。

计及磁链和电流的PMSM DTC系统中功率器件键合线老化监测方法

在闭环控制系统中,基于电参数的功率器件老化监测方法是电力电子可靠性领域的难点之一。以永磁同步电机直接转矩控制系统为例,研究基于磁链相图和电流的功率逆变器中功率器件老化状态的在线监测方法。首先,分析功率器件老化的特征,得到键合线老化引起通态电阻增加的结论;其次,研究得到功率器件键合线老化与磁链相图、直轴电流和三相电流峰值变化的关系,进而提出功率器件键合线老化的监测方法;最后,通过多组仿真实验验证了基于磁链相图和电流的在线监测方法均可实现功率逆变器中功率器件键合线老化状态的在线监测。其中,基于磁链相图的在线监测方法需要系统磁链出现一些波动时才易观测,此时功率器件处于失效状态,该方法并不可取;而基于三相电流的监测方法能够更为精确地监测功率器件老化状况,效果更为优越。

基于空间极对数宽频带耦合的双转子同步风力发电机电磁特性分析

【目的】针对传统大型永磁同步风力发电机无法实现励磁磁场的调节、传统双馈发电机无法实现直驱且存在后期维护等问题,设计了一种模块化双转子同步风力发电机。【方法】该发电机定子绕组为分数槽集中绕组(FSCW);双转子绕组均为集中绕组且采用直流激励;定子激励产生的两个主导极分别与两个转子的主导极进行磁通匝链。首先,介绍了所设计发电机的基本结构与工作原理;其次,建立了该类发电机的数学模型,并依托于FSCW理论分析其磁链、感应电动势等电磁特性;最后,建立有限元仿真模型,将仿真与理论结果进行对比分析。【结果】结果表明:定、转子齿部导磁面正对位置处磁链计算较为准确,而定、转子齿部偏移处由于含有气隙漏感存在一定的计算偏差。【结论】仿真与理论结果基本吻合,验证了所设计的模块化双转子同步风力发电机的正确性。

一种基于折息最小二乘法的PMSM磁链辨识方法

永磁同步电机(permanent magnet synchronous motor,PMSM)的磁链准确辨识是实现高性能电机控制的基础。针对传统递推最小二乘(recursive least squares,RLS)法受噪声影响小但存在数据饱和,影响辨识精度和动态性问题,以及遗忘最小二乘(recursive least squares with forgetting factor,FRLS)法避免数据饱和但存在参数估计误差与动态跟踪性能矛盾的问题,文章提出一种基于折息最小二乘(recursive least squares with discount factor,DRLS)法的磁链辨识方法。该算法在FRLS法中引入加权因子构成折息因子,采用递推方法进行磁链辨识,减小参数估计误差,提高磁链辨识精度及动态跟踪能力。通过MATLAB仿真及半实物仿真试验,验证所提磁链识别方法的有效性。

永磁同步电机永磁体状况在线监测

提出一种基于卡尔曼滤波器的永磁同步电机永磁体磁场状况在线监测方法。通过选择磁场同步旋转坐标系下定子电流和永磁体磁链为状态变量,构建估算转子永磁体磁链幅值和方向的卡尔曼滤波器。该方法能准确跟踪永磁体真实状况,对电机参数不敏感,鲁棒性强。基于动态估算的电机永磁体磁链,可为永磁同步电机控制系统实时提供准确的转子磁链信息,提高系统控制性能和效率。同时,基于永磁体磁场状况的动态监测,可防止永磁电机失磁状况的恶化,降低不可逆失磁程度,提高系统可靠性。实验结果验证了方法的正确性和有效性。

永磁同步电动机无传感器控制技术现状与发展

对近年提出的多种估算永磁同步电动机转子位置、速度的方法进行了综述,比较了各种方法的优缺点;并对中高速适用的扩展卡尔曼滤波(EKF)进行了实验研究:零速及低速时,现有的永磁同步电动机无传感器技术多是指无位置传感器,少数几种无速度估计算法都有很大的局限性。本文针对这一现状,选取基于高频信号注入+磁链观测的永磁同步电动机全速范围无传感器控制方法进行了仿真验证;最后指出复合控制方法是实现全速范围无传感器控制技术的发展趋势。

旋转电机绕组磁链的三维有限元分析

针对非正弦电压供电的旋转电机稳态或动态性能仿真,提出了一种基于三维有限元分析和网格重构的绕组磁链和端部漏电感的计算方法,根据所提出的方法,计算了一种三相12/8极开关磁阻电机的绕组端部磁链,并给出了端部漏电感随转子位置和邻近绕组电流变化的曲线族。该计算方法也可用于旋转电机或其它电磁装置的三维磁链计算。具体算例说明了考虑端部漏磁场效应的条件和必要性。

混合铁心横向磁通永磁电机的设计与分析

阐述了横向磁通永磁电机(transverse flux permanent magnet motor,TFPM)的结构特点与软磁复合(soft magnetic composite,SMC)材料的优点,提出硅钢、SMC结合的混合铁心TFPM。为了分析电机转矩及其影响因素,推导了转矩解析公式。基于3D有限元模型,通过静态磁场分析求出了式中永磁体磁链幅值及线圈电感2个变量;通过瞬态磁场分析,得到了电机的空载电动势、空载磁链、一相转矩及其平均值,转矩有限元结果与解析结果一致。样机测得的空载电动势验证了分析的正确性。结果表明,混合铁心TFPM不但结构简单、加工方便,而且转矩密度高、易于模块化。

永磁同步电机永磁磁链自适应观测器设计方法

为了实现永磁同步电机永磁体的在线监测,提出了一种永磁磁链自适应观测器的设计方法。首先,利用波波夫超稳定性定理,构建了永磁磁链自适应观测器,保证了观测器的稳定性。然后,在分析各参数误差对观测结果影响的基础上,提出了一种反馈增益的设计方法,该方法可以降低观测器对电机参数精度的依赖。通过分析观测器闭环极点的分布,优化了自适应律PI参数,拓宽了观测器稳定区域,提高了观测器的收敛性能。该方法能够准确的观测出永磁磁链,对电机参数的精度敏感性较低。通过对一台20?k W电机进行试验验证,实验结果证明了该设计方法的有效性。