了解开关电源的电磁兼容标准

　　了解开关电源的电磁兼容标准

　　由于其固有的设计特点，AC和DC和DC / DC开关电源（SMPS）产生由多个频率的射频信号组成的电磁干扰（EMI）。除了在安装这些SMPS电源的系统中干扰电路元件和功能外，这种发射也会干扰源附近的其他设备。为了确保这种排放量保持在最低限度，国际监管机构制定了规章制度；符合这种标准的SMPS转换模块被称为电磁兼容（EMC）电源。

　　电源制造商崔已经发布了一份白皮书，题为“电磁兼容性考虑开关电源”¹调查各种国际标准控制电磁调速，和更详细的描述。在美国，负责调节这种干扰的政府机构是联邦通信委员会（FCC）。FCC的规则第15部分概述了电磁干扰的控制，规定任何大于10千赫的虚假信号都要受管制。此外，根据发射的类型，它还规定了必须控制这些杂散发射的频带。

　　There are two types of EMI emissions： radiated and conducted. While radiated emissions are those radiated and coupled through the air， conducted emissions are RF signals coupled by a direct path between the source and the receptor. Direct contact is provided by a transmission line， wire， cable， printed circuit board （PCB） trace or metal enclosure. It can appear in a common or differential mode on two conductors.

　　Also， per FCC Part 15， radiated emissions must be controlled between 30 MHz and 1000 MHz， and conducted emissions must be controlled in the frequency band between 0.45 MHz and 30 MHz.