无源滤波器在开关电源中的应用分析

高频开关电源的传导性电磁干扰是电力电子装置的主要干扰源之一．国际电磁兼容法规定的电源产品的EMC指标已成为开关电源的一个极为重要的性能参数．正确分析开关电源的电磁干扰和采用适当的滤波措施是开关电源设计的前提。运用开关电源传导性电磁干扰模型，对开关电源的传导性电磁干扰机理做了全面的分析．提出一种采用无源滤波器技术来减小开关电源电磁干扰的方法。同时，引入无源滤波器插入损耗的概念．推导出高性能无源滤波电路的差模干扰与共模干扰模型．并依据无源滤波器对干扰信号的插入损耗最大原则设计开关电源输入端无源滤波器。应用结果表明．所提出的无源滤波器对开关电源高频段的电磁干扰有很好的消除效果。

Analyzing of Passive Filter applied to Power Supply

Conductive EMI of the high frequency power supply is one of the main EMI source in the power and elec-tric device, and the parameter of the power products from the international EMC rules has become one of the most critical parameters of the power supply. How to analyze the EMI of the power supply and take appropriate filter measure are the foundation for the power supply designing. This paper presents a method to reduce EMI in power supply by use of passive filter technology based on the comprehensive analysis of the conductive EMI in power supply by means of EMI mode, in-troduces insertion-loss of filter, derives the models of different mode EMI and common mode EMI of high quality passive filter, and designs the passive filter based on the principle that the insertion-loss to the EMI is most. The passive filter has been used in the special driving power supply of the EV inverter, and it is validated that the passive filter can help reduc-ing high frequency EMI of the power supply.