了解開(kāi)關(guān)電源的電磁兼容標(biāo)準(zhǔn)

　　由于其固有的設(shè)計(jì)特點(diǎn)，AC和DC和DC / DC開(kāi)關(guān)電源（SMPS）產(chǎn)生由多個(gè)頻率的射頻信號(hào)組成的電磁干擾（EMI）。除了在安裝這些SMPS電源的系統(tǒng)中干擾電路元件和功能外，這種發(fā)射也會(huì)干擾源附近的其他設(shè)備。為了確保這種排放量保持在最低限度，國(guó)際監(jiān)管機(jī)構(gòu)制定了規(guī)章制度；符合這種標(biāo)準(zhǔn)的SMPS轉(zhuǎn)換模塊被稱為電磁兼容（EMC）電源。

　　電源制造商崔已經(jīng)發(fā)布了一份白皮書(shū)，題為“電磁兼容性考慮開(kāi)關(guān)電源”1調(diào)查各種國(guó)際標(biāo)準(zhǔn)控制電磁調(diào)速，和更詳細(xì)的描述。在美國(guó)，負(fù)責(zé)調(diào)節(jié)這種干擾的政府機(jī)構(gòu)是聯(lián)邦通信委員會(huì)（FCC）。FCC的規(guī)則第15部分概述了電磁干擾的控制，規(guī)定任何大于10千赫的虛假信號(hào)都要受管制。此外，根據(jù)發(fā)射的類(lèi)型，它還規(guī)定了必須控制這些雜散發(fā)射的頻帶。

　　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.