开关电源EMI滤波器的设计与仿真

滤波是抑制传导干扰的一种常用方法,为了提高滤波器性能和缩短开发时间,针对DC-DC开关电源介绍一种简单且效果良好的滤波器设计方法.阐述EMI电源滤波器的基本原理、拓扑结构、设计原则和滤波器件的高频特性,建立滤波器插入损耗仿真模型,对设计结果进行分析,最后通过实际测试,验证设计方法的正确性.同时,在EMI电源滤波器设计的基础上,对滤波器进行拓展功能的电路设计,主要针对开关动作所引起的浪涌电压.     

EMI滤波器插入损耗自动测试系统设计

分析了EMI滤波器插入损耗原理,介绍了插入损耗人工测试方法及其优缺点,最终提出一种基于虚拟仪器技术实现EMI电源滤波器插入损耗的自动测试系统。文中所建立的测试软件在VB语言的基础上利用LabVIEW完善的可视化编程实现了EMI电源滤波器插入损耗的测试。它与以往的测试相比,不仅结构简单、操作方便,还实现了测试的自动化。     

传导性电磁干扰噪声的诊断与抑制方法

传导性EMI的测试主要是通过线性阻抗稳定网络(LISN)进行的,但测得的结果是共模(CM)噪声和差模(DM)噪声的混合信号,而滤波器的设计分为共模和差模两个部分.介绍传导性电磁干扰噪声的分离技术及EMI滤波器的阻抗匹配问题.通过实例证明,传导性电磁干扰噪声分离网络能对共模和差模噪声进行有效地诊断,为正确选用抑制噪声的EMI滤波器提供依据.     

陶瓷电容在EMI滤波器中的应用研究

电容是EMI滤波器中的重要元件,本文首先介绍了电源EMI滤波器的基本电路形式和工作原理,给出了滤波器中对电容的基本要求,重点介绍了陶瓷电容的等效电路和基本特性,强调了陶瓷电容在厚膜混合集成电路中的工艺处理要求,最后给出了在电源EMI滤波器中使用陶瓷电容的几点注意事项。     

EMI电源滤波器的设计与应用技术

在EMC领域中，EMI电源滤波器的设计和应用非常重要，它是抑制传导发射和辐射发射的有效方法之一。本文主要从以下几个方面讨论了EMI电源滤波器的设计与应用技术：1）EMI电源滤波器的基本原理、种类及主要特性指标；2）电源线上的干扰类型及EMI电源滤波器的作用：3）EMI电源滤波器的设计及工艺要求；4）EMI电源滤波器的安装要求。     

开关电源输入EMI滤波器设计与仿真

开关电源中常用EMI滤波器抑制共模干扰和差模干扰。三端电容器在抑制开关电源高频干扰方面有良好性能。文中在开关电源一般性能EMI滤波器电路结构基础上,给出了使用三端电容器抑制高频噪声的滤波器结构。并使用PSpice软件对插入损耗进行仿真,给出了仿真结果。     

EMI滤波器设计

EMI滤波器是电磁兼容设计及抑制电磁干扰的重要技术.电子电路设计人员应掌握EMI滤波器基本原理和各种类型滤波器的基本特性和使用方法,根据实际工作中的具体情况合理选择滤波元件,设计有效的EMI滤波器,从而实现EMC设计或抑制EMI的目的.在本文中主要阐述了EMI滤波器的相关理论,包括公模噪声、差模噪声、阻抗失配原则、滤波...     

航天器DC-DC模块电源电磁兼容设计

针对航天器用DC-DC模块电源电磁兼容设计中的发射干扰(RE102和CE102),探寻其产生发射干扰的根源,并分析了DC-DC模块电源输入输出端EMI的产生原因,阐述了工程中常用的抑制EMI的方法:滤波器设计法、印制板EMC设计法.对干扰测试结果超标的DC-DC模块电源采取相应的抑制措施后,测试结果有了显著的改善.     

开关电源EMI滤波器设计与验证

开关电源已广泛应用于电力电子设备中,作为一种EMI源,在设计电源电路中需前置EMI滤波器抑制传导干扰。CE102作为检测电源线传导干扰的一项电磁兼容性试验,成为电子设备尤其是军用电子设备的必测项目,测试超标即意味着设计的失败。设计了一个EMI滤波器,通过CE102测试和分析发现并解决设计存在的问题,并通过整改后的试验验证,证明设计的有效性。     

滤波器安装的重要性

[案例描述] 某产品电源线的传导发射CE测试结果超过EN55022CLASS B限制线,最大干扰超过限制线约10dB,不满足标准要求。测试结果如下图所示: [原因分析] 经过仔细检查,发现电源EMI滤波器安装存在以下问题: 1)电源滤波器固定在机柜内子架上,而机柜与子架之间因喷有绝缘漆使得子架的接地不良。根据此EMI滤波器电路模型,当接地电阻较大时,将降低EMI滤波器滤波效果。     

EMI电源滤波器的原理与分析

在工控系统或电子设备中,系统抗电磁干扰能力是衡量其稳定性或产品优劣的一个重要指标。本文首先阐述了电磁干扰源的种类及产生原因,建立EMI滤波器的典型模型,进而分析滤波器的设计机理和结构参数的选择问题。在此基础上,对EMI滤波器的插入损耗进行了仿真分析。     

An active EMI filtering technique for improving passive filter low-frequency performance

In recent years, there has been considerable interest in the development and applications of active electromagnetic interference (EMI) filters. An active EMI filter (AEF) for integrated power electronics module (IPEM) is proposed in this paper, where large passive EMI filter is replaced by small passive components and active op-amp circuit. The technique is appropriated when improved attenuation is required at relatively low frequencies and the high-frequency filtering requirements are easily met. The effectiveness of the proposed circuit has been verified by experimental results. It is demonstrated that the proposed approach is most effective in a case where it is desirable to minimize the amount of passive components in the filter.     

Compatible EMI Filters

A vexing problem in electromagnetic compatibility is the effective filtering of conducted interference from power-supply lines. Because of unavoidable and severe mismatch, conventional suppression filters operate only conditionally; such filters are often so large that they are omitted from the system. Three new classes of power-line filters without these limitations are described. They are active, truly lossy, and ruggedized ceramic filters, covering the frequency range from direct current to microwaves. Present filter test methods are shown to be misleading and are replaced by a rather simple realistic test. There is a set of filter classes that is rapidly growing in importance and, by necessity, is characterized by the absence of impedance matching. Without matching, all the elegant filter theories developed invalidate the very premise upon which they were based, and the theories are wholly inadequate and misleading. Such conditions exist for filters inserted into power lines; power wiring is contrasted with impedance-matched cabling that interconnects subsystems for irformation handling and for which conventional filtering is fully adequate. Suppression of conducted EMI (electromagnetic interference) constitutes an essential part of EMC (electromagnetic compatibility) and has, thus far, been frustrating and inadequate. Conventional EMI or RFI (radio-frequency interference) filters, because of interface mismatching are, in general, undependable. Another basic difference of power-line filters, as contrasted with information handling filters, is that they are strongly biased by the very power they have to pass. Three generic types of filters are described and discussed in some detail.     

平面耦合EMI滤波器电容和电感的确定

EMI滤波器是抑制传导电磁干扰的重要手段,但分立元件型滤波器由于其自身的缺点性能受到限制,而平面耦合型滤波器能够很好改善传统分立元件型EMI滤波器的缺点。在介绍平面耦合型滤波器结构的基础上,指出电感和电容参数是该类滤波器的最重要技术参数。通过对滤波器元件数值计算模型的建立和论证,说明共模和差模电容可以通过解析表达式计算;差模电感,即共模模块形成的漏感也可以采用解析表达式确定。但是,各线匝的电感由于与频率密切相关,无法采用对应的解析表达式确定。     

Passive and Active Hybrid Integrated EMI Filters

Two new planar integrated electromagnetic interference (EMI) filter structures that reduce the filter volume and that are based on standard printed circuit board (PCB) process technology are presented in this paper. First, a passive integrated EMI filter is presented, which results in a volume reduction of 24% compared to the discrete solution. However, this filter requires a planar ferrite core for the common-mode inductor. In order to eliminate the ferrite core and reduce the filter volume further ($-$ 40% versus discrete filter), a passive integrated structure is combined with an active EMI filtering circuit. The transfer function, the volume, and the losses of the discrete and the two integrated filters, which are designed for a 600 W power-factor-corrected converter, are compared.      

电磁干扰陶瓷滤波器综述

本文介绍了电磁干扰(EMI)的传播方式、检测技术及抑制方法。用不同的国际标准说明了各种线路网所能承受的干扰脉冲的最大振幅,对几种新型EMI陶瓷滤波器的结构与装配技术进行了描述。另外对共性能试验及质量控制提出了要求。     

Miniature low-pass EMI filters

This paper describes miniature ceramic feedthru type electromagnetic interference (EMI) filters. Electrically, the devices function as low-pass filters with a 3-dB cutoff frequency in the low-megahertz range. The filters are mechanically rugged and in many applications can be placed in the I/O connector or substituted for the existing feedthrus. The monolithic distributed filter covered in the paper behaves as a section of transmission line at all frequencies and is essentially free of undesired resonances. The theory of lossy transmission line is used to show that with a distributed dissipative filter, the effect of terminating impedances is dramatically reduced. The effect of operating environment on the electrical characteristics is also presented.     

Filters with inductance cancellation using printed circuit board transformers

Capacitor parasitic inductance often limits the high-frequency performance of filters for power applications. However, these limitations can be overcome through the use of specially-coupled magnetic windings that effectively ify the capacitor parasitic inductance. This paper explores the use of printed circuit board (PCB) transformers to realize parasitic inductance cancellation of filter capacitors. Design of such inductance cancellation transformers is explored, and applicable design rules are established and experimentally validated. The high performance of the proposed inductance cancellation technology is demonstrated in an electromagnetic interference (EMI) filter design.     

微波光子滤波技术

微波光子滤波器(MPF)是在光域内实现对微波/射频(RF)信号进行滤波的器件.由于微波光子滤波器在射频系统中具有带宽大、快速可调谐、可重构、无电磁干扰(EMI)、低损耗和重量轻等优点,因而这一类器件已经引起了越来越多的人们的兴趣.在概述微波光子滤波器基本原理基础上,分别介绍了现阶段对微波光子滤波器可调谐性、负抽头等问题基本方法的实现,并简要比较了不同方法的优缺点.最后展望了微波光子滤波技术的发展方向和技术难点.