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电路中的电磁兼容性设计电磁兼容性（Electromagnetic Compatibility，缩写为EMC）是指在一定环境中，电子设备能够在互不干扰的条件下协同工作的能力。
在现代社会中，电子设备的普及和使用广泛，因此电磁兼容性设计变得愈发重要。
1. 电磁兼容性的重要性当多个电子设备在相同的频率下共同工作时，电磁相互干扰的问题可能会出现。
例如，在医院的手术室中，存在着大量的医疗设备，如果这些设备之间没有达到良好的电磁兼容性，就可能导致干扰，从而影响医生的工作效率和患者的安全。
因此，电磁兼容性设计对于确保设备的正常运行和人身安全起到至关重要的作用。
2. 电磁兼容性设计的原则为了实现电磁兼容性设计，我们可以遵循以下原则：2.1 分隔与屏蔽为了减少电磁相互干扰，我们可以通过物理分隔和电磁屏蔽来降低信号的传播。
物理分隔可以通过合理布局电路板或设备的方式来实现，以减少同一设备内部的相互干扰。
而电磁屏蔽则使用金属外壳或金属层对电磁场进行阻挡，从而防止电磁泄露和外部干扰。
2.2 压制噪音与干扰源在电路中，存在着各种各样的噪音和干扰源，如电源噪声、开关电流等。
通过采用滤波器、隔离器和衰减器等方法，可以有效地抑制噪音和干扰源的影响，从而降低电磁干扰。
2.3 路径优化与电磁耦合在电路设计中，路径走向和电磁耦合也是需要重点考虑的因素。
通过合理的电路布局和优化路径，可以降低电磁泄露和电磁干扰的风险。
此外，对于有源元件（如晶体管、集成电路等），还可以采取电磁屏蔽和内部接地方式，以减少对周围电路的干扰。
3. 电磁兼容性测试与验证在电磁兼容性设计完成后，还需要进行相应的测试和验证，以确保设计是否符合要求。
这些测试通常包括辐射测试和传导测试。
辐射测试主要是针对设备对周围空间的电磁泄露进行测试，传导测试则是检测设备内部电路对外部电磁干扰的敏感性。
测试结果通常使用规定的电磁兼容性标准进行评估，并根据所在行业或地区的规定，对测试结果进行分析和判定。
电磁兼容性设计报告1. 引言电磁兼容性（Electromagnetic Compatibility，EMC）是指在电子器件、系统或设备之间，以及与环境之间可以相互协调地工作、相互共存的能力。
在现代社会中，电子设备的数量和种类不断增加，电磁干扰问题也越来越突出。
因此，进行电磁兼容性设计是确保电子设备正常运行的重要环节。
本报告基于某公司开发一款新型电子设备的需求，结合相关标准和技术要求，就电磁兼容性设计进行分析和评估，并提出相应的解决方案。
2. 设计要求根据项目需求，该电子设备的主要使用环境为办公室，主要功能涉及通信、数据处理和控制。
设计要求如下：- 抗干扰能力强，能在遭受电磁干扰时维持正常工作；- 对外部环境的辐射和传导干扰具有一定的抵抗能力；- 设备自身不会产生辐射、电磁泄漏等对周围设备和人员构成危害；- 符合相关国家和行业的电磁兼容性标准。
3. 设计分析3.1 环境分析根据使用环境为办公室，通常存在辐射源如电脑、打印机、Wi-Fi路由器等。
环境中可能存在的传导干扰主要来自电源线、网络线、电话线等。
在通信和控制方面，需与其他设备进行数据传输，可能会受到电磁干扰。
3.2 技术要求分析根据相关标准，我们需要考虑以下几个方面的技术要求：- 电磁辐射：在工作频率范围内，辐射功率应适应环境要求，同时符合国家和行业标准，如GB9254对辐射限值的规定；- 电磁泄漏：控制电磁泄漏在国家和行业规定的范围内，如GB17625对电磁泄漏限值的规定；- 抗干扰能力：通过设计合理的电磁屏蔽和滤波器等措施，提高设备的抗干扰能力；- 接地设计：合理规划设备的接地和线缆布线，减小接地回路的电阻，确保设备的接地有效。
4. 设计方案4.1 电磁辐射控制为满足电磁辐射限值要求，采取以下措施：- 选择合适的屏蔽材料和结构，对电磁泄漏进行有效遏制；- 优化电路布局，减小回路面积，降低电磁辐射；- 使用滤波器对电源和信号线进行滤波，减少谐波分量；- 选择精确的元器件参数，减少非线性失真的产生。
电力设备的电磁兼容性与抗干扰设计策略引言：随着现代科技的迅猛发展，电力设备在我们的日常生活中起着至关重要的作用。
然而，随之而来的问题是电磁兼容性和抗干扰设计问题，这是电力设备的关键挑战之一。
本文将讨论电磁兼容性的重要性，并提供一些抗干扰设计策略。
一、电磁兼容性的重要性电磁兼容性（EMC）是指一个电子设备在电磁环境中与其他设备协调工作的能力，也包括设备自身不会对其他设备造成电磁干扰。
良好的EMC设计可以确保设备在正常工作时不会干扰其他设备或受到其他设备的干扰。
这对于维持电力系统的稳定运行至关重要。
1. 电磁辐射与电磁感受EMC问题分为两个方面：电磁辐射和电磁感受。
电磁辐射是设备发出的电磁能量，可能对其他设备造成干扰，而电磁感受则是设备对外界电磁干扰的敏感性。
EMC设计需要考虑如何降低辐射并提高设备的抗干扰能力。
2. EMC对电力系统的影响电力设备是电力系统的核心组成部分，它们的正常运行对于电力系统的稳定性和安全性至关重要。
如果电磁兼容性不佳，设备可能会干扰其他设备的运行，造成电力系统故障和停机，对生活和生产造成不便。
二、抗干扰设计策略为了提高电磁兼容性并降低干扰，以下是一些常用的抗干扰设计策略。
1. 圆整地线布置良好的地线布置可以降低电路中的干扰电压和电流。
通过合理设计地线回路，可以减少回路的感应耦合，提高设备的抗干扰能力。
2. 滤波器的使用滤波器是常用的抗干扰器件，可以阻止高频信号进入设备或离开设备。
在电力设备的输入和输出端口上安装滤波器可以有效地减少干扰。
3. 屏蔽设计屏蔽是抑制电磁辐射和减弱电磁感受的有效手段。
通过在关键部件或电路附近添加屏蔽材料，可以阻止电磁波的传播和散射，减少干扰。
4. 系统级抗干扰设计除了在单个设备上实施抗干扰设计外，还可以通过系统级设计来提高电磁兼容性。
比如，通过优化电力系统的布局，减少设备之间的相互干扰。
三、示例：电力变压器的EMC设计作为电力系统的核心设备之一，电力变压器的EMC设计尤为重要。
电子电路中的电磁兼容性设计方法电磁兼容性（Electromagnetic Compatibility，简称EMC）是指在电子系统中，各种设备和系统之间能够以相对自由的方式进行无干扰、互不干扰的工作状态。
电子电路中的EMC设计方法对于确保电子设备的正常运行和稳定性至关重要。
本文将介绍几种常用的电磁兼容性设计方法。
一、屏蔽设计法屏蔽设计是一种常见的解决电磁干扰问题的方法。
通过在电子设备的关键部位添加屏蔽罩，可以有效地阻挡外界干扰电磁波的进入，同时防止设备自身的电磁辐射对周围环境造成影响。
屏蔽罩通常由导电材料制成，如金属板材、金属网等，具有良好的导电性和屏蔽性能。
在设计时需要考虑到屏蔽罩的结构尺寸、材料选择、接地方式等因素，以达到最佳的屏蔽效果。
二、滤波器设计法滤波器设计是另一种常见的EMC设计方法。
滤波器可以将电路中的高频噪声滤掉，从而减少电磁辐射和接收到的外界干扰。
常见的滤波器包括低通滤波器、高通滤波器、带通滤波器和带阻滤波器等。
根据设计需求和电路特性选取合适的滤波器类型，并在电路中合理布置，可以显著提高电磁兼容性。
三、接地设计法接地设计是EMC中非常重要的一环。
良好的接地设计可以有效地消除地回路的干扰，保证设备的稳定运行。
在设计中，应根据电路的特性和工作环境选择适当的接地方式，如单点接地、分级接地等。
此外，还需要合理布置接地线路，避免接地回路过长或出现共模干扰等问题。
四、降噪设计法在电子电路设计中，降噪设计是提高EMC能力的重要手段。
通过合理布置电源线路、减小信号线的长度、增加滤波电容等方式，可以有效地降低电路中的噪声水平，提高系统的抗干扰能力，从而提高电磁兼容性。
五、辐射和传导阻抗匹配设计法辐射和传导阻抗匹配是保证信号传输正确无误的重要环节。
在电子电路设计中，应根据传输线路的特性和工作频率选择合适的传输介质和线路结构，以减小阻抗不匹配带来的辐射和传导干扰。
此外，还应合理布局电路和线路，减少电磁辐射和传导噪声。
单片机硬件设计中的EMC兼容性与干扰抑制技术单片机硬件设计中的电磁兼容性（EMC）与干扰抑制技术引言在现代电子设备中，单片机（Microcontroller Unit，MCU）起到了至关重要的作用。
单片机的硬件设计必须考虑电磁兼容性（Electromagnetic Compatibility，EMC）和抑制干扰的技术。
本文将介绍单片机硬件设计中的EMC兼容性和干扰抑制技术，包括电磁干扰的来源、EMC设计要求、常用的干扰抑制技术以及正确的布线和接地技巧。
一、电磁干扰的来源电磁干扰可以由各种外部和内部因素引起。
以下是一些常见的电磁干扰来源：1. 射频辐射：包括无线通信、雷达或其他射频电源等设备产生的电磁波。
2. 电源线干扰：来自交流电源线的噪声，如谐波和干扰信号。
3. 开关电源：开关电源高频噪声会通过电源线和地线传播到其他电子设备中。
4. 过电压和静电放电：电气设备的开关、电磁阀等在操作时可能产生过电压和静电放电。
5. 瞬态电压：包括闪电击中电力线、开关电源的瞬态电压等。
二、EMC设计要求为了满足EMC设计要求，单片机硬件设计应考虑以下方面：1. 辐射和传导：抑制电磁辐射和传导干扰，以确保设备不会对其他设备产生干扰。
2. 抗干扰：增强设备的抗干扰能力，使其能够正常工作并受到外部干扰的影响较小。
3. 地址线、数据线和控制线的布局：合理的布局可以减少交叉耦合和串扰，降低电磁干扰。
4. 接地：良好的接地设计可以降低共模噪声和差模噪声，提高设备的抗干扰能力。
5. 输入输出端口的保护：通过使用适当的保护电路来保护单片机的输入输出端口，防止它们受到外部电磁干扰的损坏。
三、干扰抑制技术1. 滤波器：采用适当的滤波器可以抑制进入单片机的高频噪声。
常见的滤波器包括RC滤波器和LC滤波器。
2. 屏蔽：通过在关键部件周围添加屏蔽罩或屏蔽层，可以有效地防止电磁波的干扰。
3. 地线设计：良好的接地设计可以减少回路的回流电流，降低共模噪声，并提高设备的抗干扰能力。
电子设备的电磁兼容性设计要点是什么在当今科技飞速发展的时代，电子设备已经成为我们生活和工作中不可或缺的一部分。
从智能手机、电脑到各类家用电器，从工业控制系统到航空航天设备，电子设备的应用无处不在。
然而，随着电子设备的数量不断增加，其工作频率和集成度也越来越高，电磁兼容性问题日益凸显。
电磁兼容性（Electromagnetic Compatibility，简称 EMC）是指电子设备在电磁环境中能够正常工作，且不对该环境中的其他设备产生不可接受的电磁干扰的能力。
为了确保电子设备的正常运行和可靠性，电磁兼容性设计成为了电子设备设计中至关重要的环节。
一、电磁兼容性设计的重要性电子设备在工作时会产生电磁辐射，同时也会受到来自外部的电磁干扰。
如果电磁兼容性设计不合理，可能会导致以下问题：1、设备性能下降电磁干扰可能会影响电子设备的信号传输、数据处理和控制精度，导致设备性能下降，甚至出现故障。
2、数据错误和丢失在数据传输过程中，电磁干扰可能会导致数据错误和丢失，影响设备的正常工作和数据的准确性。
3、缩短设备寿命长期处于电磁干扰环境中的电子设备，其元器件容易受到损害，从而缩短设备的使用寿命。
4、不符合法规标准许多国家和地区都制定了严格的电磁兼容性法规和标准，如果电子设备不符合这些要求，将无法上市销售。
因此，在电子设备的设计阶段，就必须充分考虑电磁兼容性问题，采取有效的设计措施，确保设备在复杂的电磁环境中能够稳定、可靠地工作。
二、电磁兼容性设计的基本原理电磁兼容性设计的基本原理是通过抑制干扰源的发射、切断干扰传播途径以及提高设备的抗干扰能力来实现。
1、抑制干扰源干扰源是产生电磁干扰的源头，常见的干扰源包括电源、时钟电路、数字信号处理器等。
通过优化电路设计、降低工作频率、采用屏蔽措施等方法，可以有效地抑制干扰源的发射。
2、切断干扰传播途径电磁干扰可以通过传导和辐射两种方式传播。
对于传导干扰，可以采用滤波、接地、屏蔽等措施来切断传播途径；对于辐射干扰，可以通过合理布局电路、使用屏蔽罩、减小天线效应等方法来降低辐射强度。
电路电磁兼容性设计如何设计抗干扰和抗辐射电路电磁兼容性（Electromagnetic Compatibility, EMC）是指电子设备在相互干扰和和外界电磁环境下能够正常工作的能力。
在电子产品的设计中，抗干扰和抗辐射电路的设计是确保电子设备在各种电磁环境下能够稳定运行的重要因素。
本文将讨论电路电磁兼容性设计中如何设计抗干扰和抗辐射电路。
一、抗干扰电路设计抗干扰电路设计是为了减少电子设备对外界电磁噪声的敏感度，防止其发生故障或误操作。
以下是几种常见的抗干扰电路设计方法：1. 电源线滤波器：通过在电源输入端添加滤波电路，能够滤除掉电源线上的高频噪声，减小对电子设备的影响。
2. 地线设计：良好的接地设计可以有效地抑制干扰信号的传播，例如通过增加接地电感和接地电容，形成低阻抗的接地路径。
3. 屏蔽设计：在电路板的设计中，使用屏蔽罩或金属层来遮蔽电子设备内部的干扰源，从而降低对周围环境的干扰。
4. 布线设计：合理的布线可以减少信号间的串扰，例如将高频信号线和低频信号线分开布置，避免相互干扰。
5. 过压保护设计：在电路中添加适当的过压保护电路，可以避免由于外界电磁干扰引起的过压情况，保护电子设备的正常工作。
二、抗辐射电路设计抗辐射电路设计是为了减少电子设备对外界电磁辐射的敏感度，防止其自身辐射对其他设备和系统造成干扰。
以下是几种常见的抗辐射电路设计方法：1. 圆孔规则：根据电磁波波长和孔洞尺寸之间的关系，设计合理大小的圆孔，使其具有较好的屏蔽性能。
2. 接地设计：良好的接地设计可以有效地将电磁辐射信号导入地面，减小辐射功率。
3. 电磁辐射滤波器：通过添加辐射滤波器，限制高频电流在电路中的传播，减少辐射发射。
4. 屏蔽设计：在电路板设计中增加屏蔽层或屏蔽导线，使电磁辐射局限在设备内部，减少对外界的辐射。
5. 地面平面分割：通过将地面平面划分为小的分区，降低不同分区之间电荷的流动速度，减小辐射功率。
三、电路模拟与仿真为了更好地评估电路的电磁兼容性性能，可以使用电磁仿真软件对电路进行模拟和仿真。
电磁兼容设计方法电磁兼容设计是指在不影响电子设备性能的前提下，使设备之间不会发生电磁干扰或电磁辐射，也不会被其他设备的电磁干扰所影响。
下面是10条关于电磁兼容设计方法：1设计稳定的电源电路电源电路的稳定性对于电磁兼容非常重要，因为不稳定的电源电路会产生一些电磁噪声和其他干扰信号。
在进行电源电路设计时，应该使用合适的滤波器和稳压器来保证电路的稳定性，从而减少电磁干扰。
2.选择合适的布线和接地方案布线和接地方案是电磁兼容设计中非常重要的一环，因为它们会直接影响设备之间相互干扰的程度。
在选择布线和接地方案时，应该避免使用长而不必要的导线，以及过于复杂的接地方案。
相反，应采用简单的布线和接地方案，以减少可能的电磁干扰。
3.使用合适的屏蔽材料在一些需要避免电磁辐射或电磁干扰的设备中，应该使用合适的屏蔽材料来保护电路。
对于一些高频电路，应该使用铜箔、金属网、电磁波屏蔽笔、常数介质等材料来进行屏蔽。
4.合理地利用电感和电容在电磁兼容设计中，电感和电容是非常重要的元器件。
可以通过合理地设计电感和电容来减少电磁辐射和电磁干扰。
在设计PCB时，可以使用不同的电容器和电感器，以便在不对电路的性能造成负面影响的减少电磁干扰。
5.使用合适的PCB板布局PCB板布局对于电磁兼容设计非常重要，因为它会直接影响PCB的电磁特性。
在设计PCB板时，应该避免产生回流环和长度不必要的线路，并尽量缩短信号线与电源和地线的距离，以减少电磁辐射和电磁干扰。
6.使用合适的滤波器滤波器可以在保持电路性能的削弱高频电磁干扰信号和抑制电磁辐射。
在电磁兼容设计中，应该根据需要选择合适的滤波器，例如低通滤波器、高通滤波器和带通滤波器等。
7.合理地设计接口电路接口电路通常是电磁干扰和电磁辐射的主要来源。
在设计接口电路时，应该采取一些合理的措施，例如添加滤波器、减少电流激励等，以减少电磁干扰和电磁辐射。
8.进行电磁兼容测试进行电磁兼容测试可以帮助检测电路是否满足电磁兼容的要求。
Dec．2016MACHINE TOOL ＆HYDＲAULICSHydromechatronics EngineeringVol．44No．24Ｒeceived 21September 2016；revised 18October 2016；accepted 28October 2016*Corresponding author ：Qian WU ，Associate professor．E-mail ：wuqian80@163．comMACHINE TOOL ＆HYDＲAULICS Hydromechatronics Engineering http ：//jdy．qks．cqut．edu．cn E-mail ：jdygcyw@126．comDesign strategy of electromagnetic compatibility for industrial field hardware circuit systemQian WU 1*，Xin-li DENG2（1College of Computer Science and Engineering ，Chongqing University of Technology ，Chongqing 400054，China ）（2Chongqing Ｒadio ＆TV University ，Chongqing 400052，China ）Abstract ：The abominable electromagnetic environment of the industrial field put forward higher and higher elec-tromagnetic compatibility requirements to the hardware circuit system．In order to eliminate the fault of false trip-ping or false alarm etc caused by the interference of the electromagnetic interference ，the paper explored the de-sign strategy of electromagnetic compatibility in the industrial field hardware system．In this paper ，it discussed on the influence of electromagnetic environment for the hardware system and the design concept of anti electromagnet-ic interference ，made the anatomy on possible electromagnetic interference source and anti electromagnetic inter-ference mechanism ，and studied on the problem of electromagnetic compatibility design aiming at the behavior of digital circuits under electromagnetic interference．The experimental result demonstrated that the reasonable layout and circuit wiring and the good grounding are the necessary measures to be taken to resist electromagnetic interfer-ence．Engineering practice shows that the above mentioned electromagnetic compatibility design strategy is effec-tive．Key words ：Circuit hardware system ，Electromagnetic compatibility ，Anti-electromagnetic interference strategydoi ：10．3969/j．issn．1001－3881．2016．24．010Document code ：A CLC number ：TP2731IntroductionWith the rapid development of micro electronic technology ，the industrial field hardware circuit sys-tem has been moving towards the digital age．On the one hand ，the conception of the circuit system has al-ready broken through the conventional hardware circuit system ，it is developing towards to integration among the control ，measurement ，protection and data com-munications as well as direction of digital ，networ-king ，intelligence ，and the fusion application of a large number of micro electronic technology and digital technology leads to obvious vulnerability and sensitivi-ty in electromagnetic compatibility．On the otherhand ，with the degree improvement of electrization and electronization in industrial field ，it becomes more and more severe in electromagnetic environment of the hardware circuit system ，the electromagnetic interfer-ence has also become more intense ，and therefore ，it is of great significance in engineering practice to study the electromagnetic compatibility design strategy of hardware circuit system．Although many scholars havemade a more in-depth study ［1-3］，and in view of the important practical value of design strategy selection ，the following makes some discussions on the relevant issues combined with the field engineering practice lessons．2Design Concept of Electromagnetic CompatibilityThe globalization of economic technology has putforward more and more demands of anti-electromagnet-ic pollution for the industrial field hardware circuit system，and the connotation of EMC design concept is not limited to anti-electromagnetic pollution itself of the electrical and electronic equipment．Because the electromagnetic interference can lead to that the elec-trical and electronic products can not work properly and the product performance gets degradation and fail-ure，for example，in the digital system，the electro-magnetic interference can cause data loss in the process of data transmission，the automatic micropro-cessor control system such as automotive anti-collision airbag protection and braking system and so on works out of control，the electronic devices such as aircraft navigation system，medical monitor and ECG pace-maker and so on work improperly，it makes the failure of control function of industrial process such as petro-leum or chemical industry，and unintentional explo-sion of the explosive device，etc．，in short，the dete-rioration of the electromagnetic environment can lead to many adverse consequences and hazards，or even cause damage to equipment and quality accidents and other immeasurable loss．Therefore，in order to ensure the reliability of the equipment work，in the design of the hardware circuit system，it not only ensures that the design of the product is not affected by the sur-rounding electromagnetic interference and can be nor-mal operation，and also pays attention that its own is not to produce electromagnetic interference around the other equipment，and the above is the design concept of electromagnetic compatibility．Electromagnetic Compatibility（EMC）is defined as that a device or system can work properly in its elec-tromagnetic environment and is not capable of electro-magnetic interference that cannot be subjected to any object in the environment．It is studied on that under the condition of limited time，limited space and limit-ed spectrum resources，all kinds of devices can coexist and do not cause performance degradation．Clearly，the connotation of electromagnetic compatibility in-cludes two meanings，one is the equipment perform-ance that is not affected by electromagnetic interfer-ence；and secondly，the equipment does not form to not be able to withstand the interference for other e-quipment around．Therefore，the electromagnetic com-patibility is involved in many problems，such as the characteristics of the interference source in the fre-quency domain and time domain characteristics of e-lectromagnetic interference，the interference mecha-nism and the method of restraining the emission inten-sity etc．，the radiation and conduction characteristics of electromagnetic interference，the anti-interference performance of sensitive equipment，the measurement methods，measurement equipment，data processing and evaluation of measurement results in electromag-netic compatibility，and the electromagnetic compati-bility among the system and the system and electro-magnetic compatibility in the system．In addition，the study of EMC also involves the following topics，such as the study on electromagnetic interference（EMI）source in nature and its model，related to EMC，EMI measurement and evaluation methods and EMC imple-mentation techniques and skills，etc．，and it covers a very wide range of content．For example，it contains two natural sources of electromagnetic interference，lightning and electrostatic discharge，that is the study on electromagnetic interference source and its model in the artificial and natural，and it contains the meas-urement of pulse interference such as electrostatic dis-charge，electrical fast transient pulse group and elec-trical surge etc．，measurement of radiated interfer-ence，measurement of conducted interference，and measurement of open spaces，and that is the measure-ment of EMI and EMC．It also contains the study on the specific technology of electromagnetic compatibili-ty realization and implementation skills，such as the wide application of specially designed connectors and cables to suppress electromagnetic interference，and the use of filtering，binding，grounding and shielding and other technical measures to anti-electromagnetic interference．Aimed at the different specific electro-magnetic interference sources，the different anti-elec-tromagnetic interference methods are adopted．And all the anti-electromagnetic interference measures are car-ried out under the design concept of electromagnetic compatibility．3EMI Source and Anti-electromagnetic Interference Mechanism3．1EMI Source AnalysisIn order to highlight the impact of electromagnetic interference so as to more fully discuss the source of e-lectromagnetic interference，here the paper takes the protection circuit system in substation equipment as an example to make the analysis．The electromagnetic in-terference of the substation is very strong，a fast tran-sient process occurs when a switch is operated or a85Qian WU，et al．fault occurs，the over voltage frequency is extremely high，and the rising edge of extremely steep pulse e-lectromagnetic field is eradiated to the space．This kind of pulse electromagnetic field frequency band is very wide，so the EMC problem gets more prominent，the electromagnetic environment is extremely bad，and it is a very strong interference source．Specifically，these interference sources include that it is resulted in electrical transient electromagnetic phenomena in high voltage circuit breakers，operating isolation switches，lightning arrester and spark gap discharge or insulation breakdown，power frequency electric field and mag-netic field generated by high voltage device，the fast transient interference of low voltage equipment caused by switching operation variable，the electrical transi-ent electromagnetic phenomena caused by lightning，the potential rise caused by short circuit current in the grounding system，the electrostatic discharge phenom-ena by equipment shell，the high frequency field in the facility generated by the external radio transmitter，the low frequency conduction interference stringed come by power line，the high frequency radiation and conduction interference produced by equipment and the geomagnetic disturbance interference and so on．To sum up，the electromagnetic phenomena of contin-uous slow voltage fluctuation are that AC power supply of harmonic signal voltage，DC power supply ripple，the conductive interference from DC to150kHz，the radio frequency field induced interference of the power frequency magnetic field and radio frequency radiation electromagnetic field．The frequent electromagnetic transient phenomena are that the voltage transient drop with duration less than20ms，the power supply volt-age fluctuation of AC and DC，the power frequency and voltage fast transient pulse group，the damped os-cillation wave，the damped oscillating magnetic field and the electrostatic discharge and so on．Electromagnetic interference phenomenon is very complex，but generally it can be divided into three types of phenomena to be described，and it is respec-tively the low frequency interference of conduction and radiation，high frequency interference of conduction and radiation and electrostatic discharge interference of conduction and radiation．Low frequency conducted interference has harmonic，signal voltage，voltage fluctuation，voltage sag and short interruption，voltage unbalance，power grid frequency change and low fre-quency induction voltage，and the low frequency radi-ation interference has the magnetic field and electric field radiation．high frequency conducted interference has induced continuous wave voltage and current，one-way transient and transient oscillation，and high frequency radiation interference has the magnetic field，electric field and electromagnetic field（contin-uous wave，transient）．The electrostatic discharge in-terference has the conduction and radiation electrostat-ic discharge interference generated by electrostatic dis-charge．The above electromagnetic interference phe-nomenon basically covers the vast majority of electro-magnetic interference phenomenon．In the analysis of hardware circuit system in anti-interference，and the analysis of the inherent characteristics of the equip-ment in the actual environment and equipment should be considered．3．2Anti-electromagnetic Interference Mechanism For electromagnetic phenomenon，the interference formation of the hardware circuit system equipment has a prerequisite，it must have3conditions at the same time，and lack of any condition can not form an elec-tromagnetic interference on the circuit system equip-ment．They are respectively that firstly，there must be a source of electromagnetic interference，secondly it is able to accept the same interference energy sensitive receiver as the source of electromagnetic interference，and finally，the coupling channel（i．e．，the electro-magnetic interference energy propagation medium）is coupled to the interference source from the interfer-ence source to the sensitive equipment．Therefore，the electromagnetic compatibility design must be consid-ered from the two aspects that one is the lower into the hardware circuit system equipment in theＲF energy and another is to reduce the radio frequency energy in-side equipment，and the emission and interference of electromagnetic interference is transmitted through e-lectromagnetic radiation and transmission．In general，there may be4forms of interference coupling way，namely the conduction，electromagnetic field，magnet-ic field and electric field，such as the radio frequency energy is directly radiated from an interference source to the signal control cable or power cable of a sensing device，direct radiation from a source of interference to a sensitive device，through the control line and the signal line and the power line the radio frequency en-ergy is radiated from the source of interference to the sensitive equipment，and the radio frequency energy is radiated to sensitive equipment by the public power line or common signal/control cable．Electromagnetic interference and coupling methods95Design strategy of electromagnetic compatibility for industrial field hardware circuit systemare directly related．There are two kinds of situations，such as differential mode and common mode，which can be disturbed by the interference of the circuit of the sensitive equipment．Among them，the former is a series of interference in the signal source，and the lat-ter is the disturbance of the earth，that is，the inter-ference of the change of the ground potential．It can be for AC，also for the DC，and it is the main source of hardware circuit system equipment that is not work-ing properly．Common mode signal does not contain any useful information，but it has a great influence on the EMC of the hardware circuit system，because it is the most important source of radiation．Only differenti-al mode signals carry useful data and information．Compared with the differential mode current，the com-mon mode current is relatively small，but it can pro-duce a very high radiation field．Since the two trans-mission channels of the differential mode can not be absolutely consistent，the differential mode current ra-diation emission can only be weakened but absolutely can not be eliminated，and it would result in the com-mon mode current emission．The symmetry of the structure and the distance from the conductive surface and so on are likely to produce common mode current，although the value is very small，but theＲF emission energy is often very large and very large difference mode currentＲF energy．In fact，the mode current is not possible to be eliminated in theＲF return path．Of particular note is that the common mode current is difficult to predict when compared to the differential mode current on the PCB printed circuit board，be-cause it is often caused by stray capacitance to other adjacent objects to constitute a return path．But the system of one point grounding，optocoupler，floating i-solation technology，isolation transformer，double shielding technology，low impedance，transmission and transmission current instead of voltage transmis-sion can weaken the effect of common mode current．4Design Strategy of Hardware Circuit System to Suppress the Interference 4．1Analysis of Circuit System Behavior under Electro-magnetic InterferenceTaking the typical digital circuit as an example，most MCU are using CMOS technology．The CMOS device has a noise threshold，and the clock signal lev-el differences may lead to malfunction．Under electro-magnetic interference，the function of CMOS compo-nents may be destroyed，Such as electromagnetic in-terference power is too large the PN node may be de-stroyed，the high voltage insulation layer may make oxide film breakdown，current is too large may make the metal plating burned，the peak voltage is too large may cause CMOS to return to their normal state and cause circuit“crash”and so on，and so it will bring a series of consequences such as computer refusal，false action and data loss and so on．The fundamental rea-son resulted in the deviant behavior of the circuit sys-tem is that the system level EMC design strategy is not considered fully．Therefore，it is necessary to pay at-tention to the frequency spectrum distribution of the e-lectromagnetic interference source and the level of the electromagnetic interference in the electromagnetic compatibility design strategy，whether it is a continu-ous signal interference or only in the operation interval interference，electromagnetic interference and other problems caused by the physical size of the relevant input and output impedance and interference source caused by transmission circuit system equipment．Generally，the measures to restrain electromagnetic in-terference behavior include3aspects．The first is to suppress the interference which may produce electro-magnetic interference，and this is a kind of active pro-tection measure against electromagnetic interference．Secondly，it is a kind of effective anti electromagnetic interference measure to take the correct design strategy to block the interference way that may produce electro-magnetic interference．Then，to improve the robust-ness of the circuit equipment and reduce the sensitivi-ty of the circuit system equipment affected by the in-terference，and it belongs to the preventive measures to suppress electromagnetic interference．In the system level design strategy，it should pay more attention to the PCB layout，wrong design of cable and connector and wrong grounding of grounding system，and that is not improper use of interference suppression meas-ures．4．2Layout and Wiring of Circuit System Equipment Layout and wiring directly affect the electromagnetic compatibility of the system equipment．Different cir-cuits have different characteristics，and the layout and wiring of the components are not the same，because the produced interference and suppression measures are different．In the component layout，the power cir-cuit，analog circuit and digital circuit should be placed in different area，the low frequency circuit and high frequency circuit should be separated，as far as06Qian WU，et al．possible separately made a circuit board to separate their respective，and particular attention is paid to the signal transmission direction and the way and the dis-tribution of strong and weak signal device and so on．For example，large current circuit，small current cir-cuit and easy to produce noise components should be separated as far as possible from the logic circuit，the clock generator and CPU clock input can easily pro-duce noise，and therefore，they should be close to each other as much as possible．In another examples，the signal path and circuit element layout should be paid attention to the mutual coupling between the un-wanted signals that must be reduced to the maximum extent，the power line without filter and the high level signal can not be close to the low level signal，the dig-ital circuits and low level analog circuits should be Separated so as to avoid power supply common circuit and analog circuit，digital circuit to produce the cou-pling of common impedance，the logic circuit of high and medium and low speed in the PCB board should be separated by different regions，when arranging the circuit the signal line length should be minimized，to ensure that the same layer between adjacent wiring，the same plate surface between adjacent layer and the adjacent plate cannot have long parallel signal lines，electromagnetic interference source and its filter on the same piece of circuit board should be close as close as possible，the noise and non noise components should be away，the printed circuit board should be parti-tioned according to the frequency and current switch characteristics，the voltage regulating component and filter capacitor should be close to rectifier diode as close as possible，the transformer should be placed as close as possible to the AC/DC converter，rectifier and switching element and the length of the wire should be minimized as far as possible，and the high speed switching line is not parallel to the high current wiring of sensitive noise，and so on．In the specific routing strategy，it should take special measures to reduce the electromagnetic interference．For example，when the routing path，it should avoid the right angle of the turning path，all the right angle path should take45degrees angle，the stub lines may have a reflection，it should avoid to use the stub line in transmission sensitivity and high-frequency signal path．The width from the drive to the load signal path should be constant，when the path width is changed，the reflection caused by the change of the impedance of the path can be changed，and the impedance of the line is not balanced．For the tree type arrangement signal path，there can be multiple stub line，so rapid and sensitive signal line should try to avoid using tree type arrangement．Ｒadiation type signal arrangement usually has the shortest path，but it can produce re-flection and radiation interference，the high speed and sensitive signal lines should be avoided by radiation type array．If the via hole is too dense，it will produce localized impedance difference in close to via hole of power and ground，and it will influence theＲF cur-rent transmission．All deposited copper areas must be grounded，otherwise，some deposited copper areas can become an antenna，and therefore it becomes an inter-ference source of electromagnetic radiation．In the as-pect of the printed wiring strategy，it is better to use the well-shaped network wiring to the ground wire and the power supply line，and one side can be used for vertical wiring and the other side is horizontal wire，which is connected with a metal hole at the cross hole，etc．．4．3Design Strategies of Grounding SystemIn the circuit system，one of the most important ways to control electromagnetic interference is to de-sign a good grounding system．If it can be used in combination with shielding，most of the electromagnet-ic interference problem can be solved well，and the ground system structure includes digital ground（logi-cally），analog ground，enclosure（shield）and system ground．Here，it takes the grounding of PCB as an ex-ample to discuss the design strategy of the grounding system．The grounding technology can be applied to a single layer or multi layer PCB ground wire design．The design goal is to minimize the grounding imped-ance，and to reduce the potential of grounding circuit from the circuit to the power supply，and it includes the following design strategies．When the signal fre-quency is less than1MHz，the single point grounding can be used．When the signal frequency is more than 10MHz，it should be as far as possible to reduce the ground impedance，using the nearest multi-point grounding．In the1 10MHz，if the single point ground wire length should be less than the wavelength of1/20，the multi-point grounding or high frequency circuit is adopted in multi-point series connection grounding，and in short，it should choose a single point or multi-point grounding．If the circuit board has both high speed logic and analog circuits，it should separate the analog and digital circuit，and it is con-nected with the power supply terminal to the ground16Design strategy of electromagnetic compatibility for industrial field hardware circuit systemrespectively，the both ground can not be mixed，in addition，it should increase the grounding area of the analog circuit．Ground potential will change with the change of the current，so the ground wire should be as short as possible，the general should choose to be able to pass through3times the printed circuit board to al-low the current．In order to improve the anti noise a-bility of PCB，the ground line should constitute a closed loop to reduce the potential difference．The one of the multi-layer circuit board is used as a ground layer，which can not only play the role of shielding effect but also reduce the grounding resistance，so that the surrounding the printed board is provided with a circle of ground wire．In order to avoid the PCB grounding and power supply side of the insulation be-tween the thin layers to produce the capacitor，the power should be placed in the ground and the ground as near as possible in the adjacent layers of the multi-layer board．In addition，the low speed circuit and the element should make it close to the power side，the high speed circuit and the element should make it close to the ground，and when it is more than one power supply，each power should be ground respec-tively，and so on．5ConclusionsWith the rapid development of science and technol-ogy，the electromagnetic interference problem of hard-ware circuit system will become more complicated，and the problem of electromagnetic compatibility be-comes more and more serious．Field engineering prac-tice shows that as long as taking the design strategy of the above proposed suppression interference is gener-ally effective，and it can reach the requirements of the project．Here it is worth noting that the hardware sys-tem working environment must be considered in anti-interference level requirements，it is necessary to com-bine the anti-electromagnetic interference design with the field work，but not every one of the above design strategies．AcknowledgementsThis work was supported by information manage-ment and information system professional core curric-ulum construction fund of Chongqing University of Technology and science and technology project of Chongqing Municipal Education Commission（No．KJ1603811）．Ｒeferences［1］LI Shao-dong，HUANG Guo-bind，ZHANG Min．Design Strategy of electromagnetic anti-jamming for hardware system of high-voltage disconnecting switch intelligent components［J］．Electronic Design Engineering，2015，23（7）：118-125．［2］HUANG Hui．Design strategy of electromagnetic anti-jam-ming for hardware system of microcomputer relay protection ［J］．Power System Protection and Control，2010，38（20）：220-224．［3］HUANG Yi-zhuang．EMC technology for IED in substations ［J］．Power System Protection and Control，2008，36（15）：6-9．工业现场硬件电路系统的电磁兼容性设计策略巫茜1*，邓新莉21．重庆理工大学计算机科学与工程学院，重庆4000542．重庆广播电视大学，重庆400052摘要：工业现场的恶劣电磁环境对硬件电路系统提出了越来越高的电磁兼容性要求。
