Equivalent circuits of electromagnetic systems

Features of drawing equivalent circuits of electromagnetic systems of drives are considered. It is shown that the equivalent circuits with a transformer have the advantages in comparison with T-figurative circuit diagrams, that is, they do not require reduction of the parameters of the secondary circuit to the primary one and do not form shunting branches.     

Evaluating the spectrum of periodic pulling in subharmonic resonant LC circuits

We analyze the features of the oscillations arising in forced inductor–capacitor (LC) oscillators when they operate in the periodic pulling mode, under the action of a weak injection signal. In radio frequency integrated circuits, both voltage‐controlled oscillators subject to undesired couplings and injection‐locked frequency dividers behave like forced LC oscillators. These are modeled as second‐order driven oscillators working in the subharmonic (secondary) resonance regime. The analysis is based on the generalized Adler's equation, which we introduce to describe the phase dynamics of dividers of any division ratio and to derive closed‐form expressions for the spectrum components of the system's oscillatory response. We show that the spectrum is double‐sided and asymmetric, unlike the single‐sided spectrum of systems with primary resonance. Numerical and experimental results are given to validate the presented results, which significantly generalize those available in the literature. Copyright © 2014 John Wiley & Sons, Ltd.     

Electrical circuits RC,LC, and RL described by Atangana–Baleanu fractional derivatives

In this paper, the analytical solutions for the electrical series circuits RC, LC, and RL using novel fractional derivatives of type Atangana–Baleanu with non‐singular and nonlocal kernel in Liouville–Caputo and Riemann–Liouville sense were obtained. The fractional equations in the time domain are considered derivatives in the range α ∈(0;1]; analytical solutions are presented considering different source terms introduced in the fractional equation. We solved analytically the fractional equation using the properties of Laplace transform operator together with the convolution theorem. On the basis of the Mittag–Leffler function, new behaviors for the voltage and current were obtained; the classical cases are recovered when α =1. Copyright © 2017 John Wiley & Sons, Ltd.     

Reduction of electromagnetic field coupling to microwave microstrip circuits

The signals induced by an external electromagnetic field along a microstrip line on a multilayered dielectric substrate were studied. The main target of the work is not to introduce a new technique of study but to search for suitable combinations of the structural and geometrical characteristics of the printed geometry whereby the electromagnetic interference of the external field to the circuit would be reduced. This reduction is desirable in all modern applications. The results derived prove that this object can be achieved at high frequencies and when the substrate is multilayered.     

LC串联谐振和LCC串并联谐振在高压脉冲电容充电电源中的应用比较

为得到更适合高压脉冲电容充电电源的电路拓扑,对LC串联谐振和LCC串并联谐振充电电源的应用电路特性进行了比较。利用Matlab分别对LC串联谐振和LCC串并联谐振脉冲电容充电电路进行了仿真分析,通过3kW电源样机对600μF/15kV负载电容进行了充电实验,给出了LCC串并联谐振实验波形,与仿真结果一致。实验结果说明实际LC串联谐振电路由于分布电容的影响变为LCC串并联谐振,并根据附加并联电容对电路分布电容的大小进行了间接测量,LCC串并联谐振所需供电电源功率较小、电流峰值较低、充电精度较高,因而更具优越性。     

非线性电路暂态仿真中消除数值振荡的改进方法

在电力系统的电磁暂态数字仿真中,非线性元件的非线性特性将导致数值计算中产生数值振荡.引入一种新的离散方法一改进的节点分析法,对非线性元件进行处理,离散化得到等效伴随电路,然后求解.通过Matlab软件仿真得到等效后的电压波形,与ATP和PSCAD模型比较,所提算法可以有效消除数值振荡,并不会出现"毛刺"现象,适合非线性元件的仿真.     

高频电子电路用圆形截面环形磁心中电磁场的分布

为了研究当线圈缠绕于高频电子电路用圆形截面环形磁心某一段,考虑漏磁时磁心内部电磁场的分布,根据磁通连续性原理及镜像法,将绕有一个线圈的环形磁心内电磁场的分布问题,转化为绕有无穷多个线圈的无限长直磁心在其中一段磁心内的电磁场分布问题。基于麦克斯韦方程组和叠加原理,推导了环形磁心内电场强度和磁场强度的单重级数式解析计算公式。基于电场强度的计算公式,得到了涡流损耗的计算公式,与基于线圈自阻抗得到的涡流损耗计算公式进行对比,二者的计算结果吻合良好,证明了本文分析方法及所得公式的正确性。电场强度和磁场强度的计算结果分析表明,本文结论也同样适用于磁心磁导率很高或线圈均匀密绕于磁心表面,即漏磁通很小可以忽略的情况。     

SPWM波在高频逆变电源变压器中的电磁特性

为了提高高频环逆变电源的效率,有必要对变压器建立仿真模型,对传递SPWM波的高频环逆变电源变压器运行情况、铁心磁饱和现象及铁心损耗进行研究。基于Ansoft/Maxwell有限元仿真分析软件设计了一个变压器模型,对不同调制比和载波比下的SPWM波对变压器的影响,不同一次电压下的励磁电流特性和变压器铁心损耗进行了分析,为高频环逆变电源变压器的设计提供了依据。     

Transient electromagnetic phenomena in the secondary circuits ofvoltage and current transformers in GIS (measurements and calculations)

The paper presents numerical and experimental evaluation of the transient behavior of gas insulated substations (GIS). The electrical equivalent circuits chosen to represent the main components of GIS are implemented in the Electromagnetic Transients Program (EMTP). The effect of mutual couplings between phases are included in the model, which is of importance for analyzing a modern GIS, containing three-phases in one encapsulation. With the help of this model the generation and propagation of transients inside GIS have been evaluated with regard to transient overvoltages in the secondary circuits of voltage- and current transformers. The established model results have been successfully verified experimentally for a 123 kV GIS     

基于电磁-热耦合场的输电线路高频激励融冰分析与计算

覆冰事故是影响架空输电线路安全运行的重要因素。根据架空输电线路高频激励融冰的原理分析,建立了输电线路电磁-温度场二维有限元分析模型,确定耦合场的边界条件,求解得到输电线路内部磁场分布情况。将得到的焦耳热和介质热作为热源直接转化到热场模型中计算分析,并采用有限元ANSYS软件仿真求解出覆冰输电线路温度随施加激励时间的分布情况。此外,基于此模型通过仿真分析得出不同的外界因素对高频激励融冰时间的影响规律。该研究成果为高频激励融冰技术应用于输电线路融冰提供一定的参考价值。     

初论高压一体化电流、温度传感器

介绍了高压一体化电流、温度传感器的工作原理和结构,以及无线输电的供能方式,并与国内外相关产品进行了技术对比。实验结果表明,一体化电流、温度传感器是一种功能全,体积小、测量精度高的新型传感器,可广泛应用在高低压交直流供电和用电系统中。     

高压大容量隔爆型水冷三相异步电动机

高压隔爆型水冷三相异步电动机具有高效、节能、低振动、低噪声等特点,文章提供了一种水冷隔爆型电动机的设计方案,并给出了试验结果,为用户提供了一种选择。     

高压变频器用的功率器件

大功率高压变频器之所以技术较复杂,其成本价格也相当高昂,是因为高压变频器必须采用数量庞大的功率器件以串并联的方式构成整流电路和逆变电路。由于中国是能源消耗大国,能源利用效率相对较低,而中国的能源储备相对贫乏,因此国家开始大力提倡各种节能措施,并着重推荐了变频器调速技术。变频器产生的最初目的是速度控制,而目前相当多的运用是以节能为主要目的。本文主要介绍了高压变频器所用的功率器件的种类、参数及其应用技术。     

高次谐波产生的原因,危害及其抑制措施

阐述了高次谐波产生的原因、危害 ,介绍了高次谐波的抑制方法并对这些方法进行了比较 ,认为有源电力滤波器是谐波抑制装置的发展方向。     

静止无功发生器在高压电力系统中的应用

静止无功发生器是柔性交流输电系统中重要的电力电子装置 ,它集中了电力电子和微电子技术的优点 ,是高压电力系统稳定电压和提高功率因数的理想装置 ,具有良好的应用前景。介绍了静止无功发生器工作原理和控制方法 ,探讨了它在高压电力系统中应用的相关问题 ,包括消除静止无功发生器自身谐波的多重化技术及曲折变压器联接方式。模拟实验结果验证了所述控制方法的可行性     

一种高压SJ—nLDMOS的准饱和特性研究

研究了高压sj—nLDMOS器件中的一种特殊的电流饱和现象一准饱和效应。利用仿真工具SILVACO,对三维nLDMOS器件进行仿真,并从准漏极电压仉’和漂移区耗尽层入手,研究了准饱和效应的物理机制。与常规双RESURF—nLDMOS器件相比,在不改变器件击穿电压的情况下,降低了器件的导通电阻,大幅度提高器件的开态准饱和电流。     

高压半导体功率器件的寿命控制工程述评

对应用于高压功率器件的寿命控制技术进行了述评。着重分析了高能H^ 辐照、He^2 辐照等局域寿命控制技术，利用这种技术有可能实现高压功率器件突破性的进展。     

The analysis of balanced, linear differential circuits

The salient characteristics of differential electronic systems are overviewed, and a generalized low frequency analysis of these systems is presented. This analysis, which produces accurate Thevenin equivalent circuits for the input and output ports of balanced differential pairs, discloses a shortcoming pervasive of much of the electronic circuits textbook literature. In particular, an account is rarely made of the dependence of the differential input and differential output resistances on respective common mode input and output resistances. It is shown that the functional relationship of differential resistance to corresponding common mode resistance is easily factored into the generalized analysis of balanced differential pairs. The paper goes on to demonstrate that the failure to account for this dependence can lead to significant analytical errors when the common mode resistance at an input or an output port of a balanced pair is not substantially larger than the corresponding differential mode resistance. Such a situation often materializes when circuits are designed to deliver very low equivalent input noise and/or very wide passbands