开关电源EMI源阻抗在线测量的实现

发布时间：2018-02-14 18:17

本文关键词： 源阻抗在线测量双电流探头法直接数字频率合成(DDS)　出处：《华中科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：常用抑制电磁干扰的各种途径中,EMI滤波器是降低电路中传导干扰的有效方法。噪声源的内阻抗特性测量方法的发展,极大的提高了EMI滤波器设计效率,但目前噪声源阻抗的测量与EMI滤波器设计总是分立进行的,无法形成一个有机的整体。这种离线的设计,使得滤波器不能跟踪实际环境中的噪声源而做出改变,导致滤波器失效。本文基于频率特性测试仪的双电流探头法,实现噪声源阻抗的在线测量。通过分析噪声源的内阻抗测量对EMI滤波器设计的重要性,详细介绍了双电流探头法在噪声源阻抗测量中的应用,通过分析其测试原理设计制作了电流探头,改进了短路阻抗的测试方法,按照测试步骤完成了对待测设备(EUT)噪声源阻抗的测量。为实现在线测量,设计和制作了一个基于直接数字频率合成(DDS)和FPGA技术构建的数字频率测试平台,详细介绍了设计原理,给出了设计方案和设计参数,印制电路板(PCB),完成了简易频率特性测试仪制作。通过实验验证了其信号扫频源的输出功能,以及频谱测试功能。本文基于频率特性测试仪的双电流探头法对一个微型光伏逆变器电路的噪声源的共模和差模内阻抗进行在线测量,并将其与普通的源阻抗测试方法进行比较,验证了该测量方法的有效性。
[Abstract]:The EMI filter is an effective method to reduce the conduction interference in the circuit. The development of the internal impedance measurement method of the noise source has greatly improved the design efficiency of the EMI filter. However, the measurement of the impedance of the noise source and the design of the EMI filter are always separate and cannot form an organic whole. This off-line design makes the filter unable to track the noise source in the actual environment and make changes. In this paper, the on-line measurement of the noise source impedance is realized based on the dual-current probe method of the frequency characteristic tester. The importance of the internal impedance measurement of the noise source to the design of the EMI filter is analyzed by analyzing the importance of the internal impedance measurement of the noise source to the design of the EMI filter. The application of double current probe method in noise source impedance measurement is introduced in detail. The current probe is designed and manufactured by analyzing its testing principle, and the method of short circuit impedance measurement is improved. In order to realize on-line measurement, a digital frequency testing platform based on direct digital frequency synthesizer (DDS) and FPGA technology is designed and manufactured, and the design principle is introduced in detail. The design scheme and design parameters are given, and the printed circuit board (PCB) is used to fabricate the simple frequency characteristic tester. The output function of its signal sweep frequency source is verified by experiments. In this paper, the common mode and differential mode impedance of the noise source of a miniature photovoltaic inverter circuit is measured online based on the dual-current probe method of the frequency characteristic tester. The effectiveness of the method is verified by comparing it with the common source impedance measurement method.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM934.7

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