电动汽车EMI根源定位方法及优化策略

介绍了电动汽车电磁兼容干扰源常用定位方法及优化策略。为快速定位干扰源,在整车EMC测试中采用系统间与系统内排除法,同时借助近场探头扫描、零部件测试不断缩小排查范围。最终确认,导致发射超标的器件为电池管理系统主板的隔离电源芯片ADUM5401。     

多探头球面近场天线测试效率提升方法

为最大化提升球面近场测试效率,针对多探头球面近场测试系统的不同采样方案进行了研究,并通过仿真和测试对比了不同采样方案对测试效率的影响.首先利用电磁仿真软件计算出所设计喇叭天线的近场和远场方向图数据;然后利用基于球模式展开法的近场到远场变换算法,从理论上验证了在满足采样规则的前提下,通过适当增加方位上的采样间隔可实现测试...     

某工业产品电磁辐射测试解析及整改验证

在工科医类产品中,控制驱动电机类产品非常常见,该类电路中存在频繁的信号跳变,是电磁兼容测试中辐射发射超标的主要原因之一.文章针对某型工业产品辐射发射超标问题,借助近场探头和频谱仪等工具,对干扰源进行了定位和超标原因分析,重点对控制电路部分进行了理论分析,并采用增加元器件滤波、屏蔽等方式进行电磁兼容优化设计.测试结果表明,超标部分得到了有效抑制,电磁兼容整改措施有效.     

国内外电磁兼容技术新进展

随着电磁环境的日益复杂,电磁兼容技术也随之不断发展。本文首先以电磁兼容技术的内涵延展为基础,重点对电磁兼容技术的预测、仿真、测试、标准及材料的新进展进行了论述。     

高性能近场测试电场探头和磁场探头研究进展

回顾了近场电场探头和磁场探头的发展脉络,介绍了国内外研究团队在近场探头研究方面的进展,并重点介绍了本团队在超宽带电场探头、磁场探头,高灵敏度谐振探头,有源电场探头、磁场探头等方面的研究成果。提出了电磁场探头的组合式一体化设计思想,并通过案例验证了其有效性,供从事近场测试的科研人员参考。     

多探头球面近场的校准

在多探头球面近场测试系统中,每个探头形成的测试通道间幅度和相位特性是存在差异的,各个通道不一致,如不进行修正,将会影响近场测试精度.介绍一种多探头天线测量系统的探头校准方法,属于无线通信技术领域,利用校准工具按照正确的步骤校准,可以实现多探头相位和幅度的自动化校准.本校准方法有效校准探头极化间相互影响造成的误差,提高校准的精度和可靠性,并且可以满足高性能天线的测量要求.     

基于有限元法的高频开关电源PCB电磁兼容设计与仿真

在高频开关电源的设计中,功率开关器件在高频下的通断会产生强大的EMI,所以不可避免的会出现电磁兼容问题。这篇文章应用有限元法分别对自动布线后的高频开关电源PCB与按照电磁兼容设计规则布线后的PCB进行仿真,得到其在200 MHz、600 MHz、1 GHz频率处的近场辐射参数。仿真结果表明:自动布线生成的高频开关电源PCB近场辐射的范围和数值均较大,电磁干扰较强。根据电磁兼容的相关规则对PCB进行优化后,近场辐射的范围和数值均有所减小,提高了PCB板的电磁兼容性。     

基于现场测试数据的电磁兼容模型综合方法*

经常性的现场测试是掌握电子系统实时指标和电磁兼容状况的基本手段。针对电磁兼容测试数据较多但应用 不充足的现状,提出了电磁兼容模型综合的概念,结合电磁兼容原理,实现了运用数理统计方法和人工神经网络技术对电磁测 量结果进行数据挖掘,对统计分析方法进行了实用性设计,研究了神经网络训练方法的实用性及学习率确定方法。电磁兼容 模型综合可建立或修正模型,归纳综合设备电磁参数及系统和平台电磁兼容性能变化规律,实现电磁兼容信息综合与状态预 测,为增强系统电磁兼容针对性测试、主动管理和预知性维护与保障提供技术手段。     

电气电子产品电磁兼容性测试技术及对策技术研讨会闭幕

电气和电子产品的电磁兼容性问题日益受到国内外各厂商和各国政府的重视,尤其是欧共体根据89/336/EEC指令从96年1月开始强制执行电磁兼容性标准以后,在世界范围内产生了对电气和电子产品进行电磁兼容性测试和研究的热潮.我国技术监督局和各部委也相继颁布了一系列新的国家标准和部级行业标准,都把电磁兼容性测试列为这些标准的重要条款.为了迅速提高我国电气和电子产品的电磁兼容水平,推动国内电磁兼容领域的技术进步,中国电工技术学会电磁兼容专业委员会与国内专业生产电     

家用电器的电磁兼容性测试技术

本论文首先对电磁兼容的发展现状及研究意义进行阐述,然后从两方面详细论述了电磁兼容的概念,并对家用电器的电磁兼容性进行介绍。在此基础上,对家用电器的电磁骚扰起源简单分析,其次对家用电器的干扰原因进行着重介绍。接着对家用电器电磁兼容性测试技术进行研究,深入分析了我国目前电磁兼容技术的状况。最后,对论文进行了总结,同时也为后期的电器电磁兼容技术的进行提供了参考,并对未来相关研究工作做了展望。     

Applications of the Near-Field Techniques in EMC Investigations

A completely automatic near-field mapping system has been developed within the Research Institute for Electronic Embedded Systems (IRSEEM) in order to determine the electromagnetic field created by electronic systems and components. This test bench uses a 3-D positioning system of the probe to make accurate measurements. This paper presents some applications of the near-field techniques in EMC investigations. In the first part, near-field measurements are used to locate precisely the electromagnetic sources of a limiter device. In the second part, we present an equivalent model of the radiated emission of an integrated circuit. In the last part, the near-field test bench is used to characterize faults in a cable.     

电磁兼容自适应扫描系统的研制

针对近场测试系统的市场需求及该系统在国内相关领域的研究空白,设计并实现了一款新型电磁兼容扫描系统。该系统可对PCB板、线缆、机箱等被测设备进行全局扫描、局部扫描或自适应扫描,并以三维彩色图形的形式显示被测设备的电磁辐射状态,实现电磁场＂可视化＂。提出了＂自适应扫描＂原理,设计并实现了步进长度可调整的自适应式扫描的技术方案,从而达到节省扫描时间、提高效率并降低成本的效果。     

Complex-Point Dipole Formulation of Probe-Corrected Cylindrical and Spherical Near-Field Scanning of Electromagnetic Fields

A probe-corrected electromagnetic theory based on complex-point dipoles is presented for computing the field of an arbitrary source of finite extent (for example a test antenna) from measurements of its near field on a cylindrical or spherical scanning surface. By representing the probe with complex-point dipoles, probe correction is achieved by simple factors that involve Hankel functions evaluated at complex points. Only four complex-point dipoles are needed to represent a typical precision probe used in near-field measurements. The theory uses neither translation and rotation theorems nor differential operators. One disadvantage of the theory is that it employs nonlinear optimization to determine the parameters of the probe model. The complex-point dipole representation of the probe makes realistic simulations of near-field scanning systems straightforward. The cylindrical theory is validated through a numerical example. The spherical theory is validated by experimental data.     

Spherical near-field facility for microwave coupling assessments inthe 100 MHz-6 GHz frequency range

This paper describes a spherical near-field facility set up at the Centre d'Etudes de Gramat (CEG) to perform low-power microwave coupling assessments. Specifically, this facility has been designed to determine the coupling cross section of a complex object. However, it can also be used for the characterization of any radiating system in electromagnetic compatibility (EMC) or high-power microwave (HPM) environments. The near-field approach is shown to be complementary and to offer increased flexibility when compared to other more conventional measurement techniques. More particularly, the use of a probe array in the upper part of the frequency band significantly speeds up the near-field measurement process. Consequently, broadband and multiparameter acquisitions can be performed within acceptable duration. The examples given in this paper provide a broad illustration of the capabilities of near-field techniques for EMC and HPM applications     

Reverberating chambers as sources of stochastic electromagneticfields

Reverberating chambers are of recognized relevance in many EMC applications since they allow us to generate a reference electromagnetic statistical field. This paper investigates the electromagnetic field in reverberating chambers. Reverberating chambers are large overmoded cavities wherein a nonstationary electromagnetic field is present. This electromagnetic field is stochastic in nature; therefore, proper analytical tools need to be considered in order to characterize it. We deal with the theoretical aspects related to the characterization of the electromagnetic field inside the chamber and with the application to the case of the reverberating chamber of the Istituto Universitario Navale     

用准静态电磁场方法研究扫描近场光学显微镜的耦合特性

为了研究扫描近场光学显微镜(SNOM)中探针和粗糙样品表面的耦合相互作用,采用准静态电磁场理论的方法,提出了一种模拟SNOM的理论模型。在该模型中,探针和样品突起由极化偶极子表示,样品平面的诱导极化效应由影像偶极子表示,应用偶极子辐射理论可以得到系统的场方程,通过自洽的方法可以求出任意偶极子位置处的严格解析解。该方法与通过并矢传播子方法得出的结果完全相同,其优点在于实用性和计算的简便性。     

Reverberating chamber electromagnetic field in presence of anunstirred component

A theoretical model for the electromagnetic field within a reverberating chamber in presence of an unstirred component is presented. Due to the stochastic nature of the electromagnetic field within the chamber, a statistical electromagnetic approach is developed and tested versus measurements. On the theoretical side, such a physical model is representative of many complex electromagnetic environmental situations, e.g., urban environments, and, therefore, it is of great relevance in the EMC field. On the applicative side, the model can be furthered in order to characterize a reverberating chamber whether it is well operated or not and to set up an environment with a specific amount of direct coupling in conjunction with a stochastic field     

Near-field diagnostics of small printed antennas using theequivalent magnetic current approach

A near-field to far-field transformation based on the antenna representation by equivalent magnetic current (EMC) sources has been proposed and validated experimentally on large high-directivity antenna arrays. In this paper, the use of EMC is extended to the diagnostics of low-directivity printed antennas. The limitation of the near-field to far-field transformation applied to EMC models of low-directivity antennas, caused by the finite dimensions of the antenna ground plane, is demonstrated. A method to partially overcome this limitation by including the contribution of diffracted rays is implemented, and its effectiveness is demonstrated with antenna prototypes. It is shown that the agreement between the far-field patterns measured in an anechoic chamber and the patterns computed from the EMC model obtained from the near-field measurements is significantly improved upon, within a sector of ±90° with respect to the antenna boresight in the E plane. The influence of the near-field sampling density and topology of the EMC model on the accuracy of the predicted far-field pattern is examined     

EMC混响室电磁场模态研究

混响室谐振腔激励的三维电磁场的推导一般采用并矢格林函数的方法,物理意义不太明显。用本征函数迭加的方法推导混响室有源激励的电磁场分布公式,有利于正确建立混响室电磁结构模型,树立正确的物理概念。并根据公式及其推导过程,分析了混响室EMC电磁工作机理,以此将EMC混响室电磁工作状态按模式状况进行了系统地分类,为混响享研究设计提供理论指导。