论文总字数：22491字

摘 要

关键词：滤波器；插入损耗；尺寸变化；测试夹具；电磁屏蔽

The Perfect Fixture Design Of Automatic Test System For Filter

Number:02012419 Name:LiuJiaxin

Supervised by JingShenhui

Abstract：The EMI filter is mainly used to interfere with the high frequency interference signal, its main performance parameters are insertion loss. But the EMI filter insertion loss characteristics of the test fixture is lacking, the existing test fixture can not adapt to a variety of different sizes of filters, in the actual production work is not inconvenient. The completion of this design is to design a test fixture that can meet the different sizes of the filter on the basis of the existing. After being familiar with the test method of the filter, according to the change range and technical requirement of the filter size, the box shape and the structure of the filter test fixture are determined. By using the concept of movable partition board to flexibly adapt to different sizes of filter, the electric continuity of test fixture is ensured by conductive rubber. According to the assembly condition and operation mode of the test fixture, the design and adjustment of the structure size of the parts are carried out. Finally get a complete filter test fixture, which can adapt to a range of different sizes of filter, simple operation, electromagnetic shielding effect is good, can be used repeatedly, the filters of different sizes of insertion loss characteristics of automatic test. In physical testing, the test fixture is perfect to show the adaptability of different sizes of filter, the test data before and after the use of fixture also shows that the filter test fixture excellent electromagnetic shielding effectiveness. The mechanical structure of the design and conductive rubber to achieve the two elements of the adjustable and shielding, in the current filter test fixture with intuitive innovation and practicality.

Key words: filter; insertion loss; changing size; testing fixture; Electromagnetic shielding

目 录

1、前言 1

1.1、EMI滤波器介绍 1

1.1.1、EMI滤波器的基本工作原理 1

1.1.2、EMI滤波器在电磁兼容中的作用 2

1.2、EMI滤波器的插入损耗特性 3

1.2.1、插入损耗的测试原理 3

1.2.2、插入损耗的测试方法 4

1.2.3、影响插入损耗测量的因素 5

1.2.4、EMI滤波器的安装 5

1.3、研究EMI滤波器测试夹具的意义 6

2、滤波器测试夹具设计方案 7

2.1.、夹具的基本要素 7

2.2、滤波器尺寸 8

2.3、课程关键问题及难点 8

2.4、夹具设计方案 8

3、夹具的结构尺寸设计 11

3.1、底座的结构尺寸设计 11

3.2、活动隔板的结构尺寸设计 12

3.3、空腔体的结构尺寸设计 13

3.4、前后挡板的结构尺寸设计 14

3.5、抽拉结构的尺寸设计 15

3.6、簧片导电橡胶的选用 19

3.7、配合结构尺寸设计及屏蔽效果校核 20

3.7.1、夹具配合结构尺寸设计 20

3.7.2、夹具电磁屏蔽效果校核 20

4、滤波器测试夹具使用说明 21

5、滤波器测试夹具实物测试 22

6、结论 25

致 谢 26

参考文献 27

滤波器插入损耗自动测试夹具完善设计

1、前言

1.1、EMI滤波器介绍

EMI电源滤波器也称“电网滤波器”、“进线滤波器”，它和普通的低通滤波器不同，其使用环境具有以下几个特征：工作电压高、额定电流大，并且要求其能够承受瞬时大电流的冲击，源端和负载端的阻抗复杂多变。其关键技术指标是：插入损耗、额定电压和截止频率等。EMI滤波器通常是低通滤波电路，由串联电抗器和并联电容器这两个部分组成。它的作用是阻碍高频干扰信号，保证设备在要求的正常工作频率下进行运作。

图1-1 常见的EMI滤波器

1.1.1、EMI滤波器的基本工作原理

在电源设备输入引线上存在两种电磁干扰噪声信号，分别是共模和差模。如图1-2所示。共模噪声在交流输入引线与地之间存在的电磁干扰噪声，它是在交流输入线上传输的电位相等、相位相同的干扰信号，即图1-2中的电压和，而差模噪声是交流输入引线之间存在的电磁干扰噪声称，它是在交流输入线传输的相位差180°的干扰信号，即图1-2中的电压。

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