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电磁干扰(EMI)滤波器|EMC滤波器的基本种类和特点

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发表于 2008-1-28 10:06:02 | 显示全部楼层 |阅读模式

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  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 常用的电源滤波器都是由电感和电容构成的无源低通滤波器,按照构成方式的不同分为 L 型、 T 型和 型滤波器三类,以下分别介绍这三类的基本拓扑: 1、 L 型滤波器 <p>&nbsp;&nbsp;&nbsp; L 型滤波器是最常见的基本滤波器,其基本结构如下: </p><img src="http://www&#46;dianyuangu&#46;com/jiaocheng/tupian/88/1&#46;gif" border="0" /> <p>&nbsp;&nbsp;&nbsp; 其特点是由单级的有两个储能元件,剪切频率为 <img src="http://www&#46;dianyuangu&#46;com/jiaocheng/tupian/88/2&#46;gif" border="0" /> ,由于一个电感或则电容会有 6dB/ 倍频的插入损耗或则说 20dB/ 十倍频,故在理想状态下在阻带可以提供 12dB/ 倍频,或 40dB/ 十倍频的插入损耗,图三给出了输入源阻抗和输出负载阻抗为 50 W 纯阻时的插入损耗曲线。双级滤波器在理想状态下可以提供 24dB/ 倍频的插入损耗。 </p><img src="http://www&#46;dianyuangu&#46;com/jiaocheng/tupian/88/3&#46;gif" border="0" /> <p>图三:单级 L 滤波器插入损耗曲线 </p><p>&nbsp;&nbsp;&nbsp; 除此之外, LC 滤波器其输入为电感,输出为电容,当频率<i> f </i>升高时,输入即呈现高阻而输出呈现低阻。 相反 CL 滤波器其输入为电容,输出为电感,当频率<i> f </i>升高时,输入即呈现低阻而输出呈现高阻。 </p><p>2 、 型滤波器 </p><p>&nbsp;&nbsp;&nbsp; 在开关电源或则 UPS 应用中,经常用 此种类型的滤波器,其能在明显提高插入损耗,降低噪声干扰。 </p><img src="http://www&#46;dianyuangu&#46;com/jiaocheng/tupian/88/4&#46;gif" border="0" /> <p>&nbsp;&nbsp;&nbsp; 单级可以提供 18dB/ 倍频,或 60dB/ 十倍频的插入损耗。双级可以提供 30dB/ 倍频的插入损耗。输入和输出都是容性阻抗,在频率升高时,输入和输出都呈现出低阻。 </p><p>3 、 T 型滤波器 </p><p>&nbsp;&nbsp;&nbsp; T 型滤波器也是常用的基本滤波器,其拓扑结构如下: </p><img src="http://www&#46;dianyuangu&#46;com/jiaocheng/tupian/88/5&#46;gif" border="0" /> <p>&nbsp;&nbsp;&nbsp; 单级 T 型滤波器有三个储能元件,理想状态下在阻带可以提供 18dB/ 倍频,或 60dB/ 十倍频的插入损耗。双级 T 型滤波器可以提供 30dB/ 倍频的插入损耗。由于 T 型滤波器的输入和输出都是感性元件,当频率升高时,滤波器呈现出高输入阻抗和高输出阻抗。</p><p><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-font-kerning: 1&#46;0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">到</span><span lang="EN-US" style="FONT-SIZE: 9pt; FONT-FAMILY: "Times New Roman"; mso-font-kerning: 1&#46;0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"><a href="http://www&#46;emcgarden&#46;net/"><span lang="EN-US" style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"><span lang="EN-US">电磁兼容</span></span>(EMC)<span lang="EN-US" style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"><span lang="EN-US">和电磁干扰</span></span>(EMI)<span lang="EN-US" style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"><span lang="EN-US">学习园地</span></span></a>( <a href="http://www&#46;emcgarden&#46;net/">http://www&#46;emcgarden&#46;net</a> )</span><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-font-kerning: 1&#46;0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">学习各种电磁兼容</span><span lang="EN-US" style="FONT-SIZE: 9pt; FONT-FAMILY: "Times New Roman"; mso-font-kerning: 1&#46;0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体">(EMC)</span><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-font-kerning: 1&#46;0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">设计整改经验知识以及各种电磁干扰</span><span lang="EN-US" style="FONT-SIZE: 9pt; FONT-FAMILY: "Times New Roman"; mso-font-kerning: 1&#46;0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体">(EMI)</span><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-font-kerning: 1&#46;0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">解决措施,到</span><span lang="EN-US" style="FONT-SIZE: 9pt; FONT-FAMILY: "Times New Roman"; mso-font-kerning: 1&#46;0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体"><a href="http://www&#46;studyemc&#46;net/"><span lang="EN-US" style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"><span lang="EN-US">电磁兼容</span></span>(EMC)<span lang="EN-US" style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"><span lang="EN-US">和电磁干扰</span></span>(EMI)<span lang="EN-US" style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"><span lang="EN-US">下载园地</span></span></a>( <a href="http://www&#46;studyemc&#46;net/">http://www&#46;studyemc&#46;net</a> )</span><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-font-kerning: 1&#46;0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">下载各种</span><span lang="EN-US" style="FONT-SIZE: 9pt; FONT-FAMILY: "Times New Roman"; mso-font-kerning: 1&#46;0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体">EMC</span><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-font-kerning: 1&#46;0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">标准和</span><span lang="EN-US" style="FONT-SIZE: 9pt; FONT-FAMILY: "Times New Roman"; mso-font-kerning: 1&#46;0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体">EMC</span><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-font-kerning: 1&#46;0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">资料以及安规防雷静电放电</span><span lang="EN-US" style="FONT-SIZE: 9pt; FONT-FAMILY: "Times New Roman"; mso-font-kerning: 1&#46;0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体">ESD</span><span style="FONT-SIZE: 9pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-font-kerning: 1&#46;0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">等资料。</span>&nbsp;</p><p>4 、多级滤波器 </p><p>&nbsp;&nbsp;&nbsp; 当干扰噪声频率和有用信号频率靠的比较近时,单级滤波器就起不到作用,此时需要选用多级滤波器,它们是以上多个单级滤波器的组合: </p><img src="http://www&#46;dianyuangu&#46;com/jiaocheng/tupian/88/6&#46;gif" border="0" /> <p>&nbsp;&nbsp;&nbsp; 现总结各种滤波器的特性如下: </p><table cellspacing="0" cellpadding="0" border="0"><tbody><tr><td valign="top" width="208"><p>滤波器类型 </p></td><td valign="top" width="208"><p>阻带衰减斜率 </p></td><td valign="top" width="208"><p>阻抗特性 </p></td></tr><tr><td valign="top" width="208"><p>LC 型 </p></td><td valign="top" width="208"><p>12dB/ 倍频( 40dB/ 十倍频) </p></td><td valign="top" width="208"><p>输入感性、高阻,输出容性、低阻 </p></td></tr><tr><td valign="top" width="208"><p>CL 型 </p></td><td valign="top" width="208"><p>12dB/ 倍频( 40dB/ 十倍频) </p></td><td valign="top" width="208"><p>输入容性、低阻,输出感性、高阻 </p></td></tr><tr><td valign="top" width="208"><p>T 型 </p></td><td valign="top" width="208"><p>18dB/ 倍频( 60dB/ 十倍频) </p></td><td valign="top" width="208"><p>输入感性、高阻,输出感性、高阻 </p></td></tr><tr><td valign="top" width="208"><p>o 型 </p></td><td valign="top" width="208"><p>18dB/ 倍频( 60dB/ 十倍频) </p></td><td valign="top" width="208"><p>输入容性、低阻,输出容性、低阻</p></td></tr></tbody></table>
发表于 2008-3-26 17:39:32 | 显示全部楼层
AC输入的那个power entry module带filter和不带filter的,哪位达人能够推荐几个好点品牌啊,谢谢
发表于 2008-4-30 10:21:07 | 显示全部楼层
有谁知道Notch filter 资料

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