共模電感也叫共模扼流圈，常用于電腦的開關電源中過濾共模的電磁干擾信號。導線上產生共模電流時在導線上會產生強烈的電磁輻射，對電子產品產生電磁干擾，影響產品的性能指標。這時就有需要使用共模電感。

共(gong)(gong)模(mo)(mo)電(dian)(dian)(dian)(dian)感(gan)的(de)(de)(de)(de)濾(lv)波(bo)原(yuan)理：共(gong)(gong)模(mo)(mo)電(dian)(dian)(dian)(dian)感(gan)的(de)(de)(de)(de)濾(lv)波(bo)電(dian)(dian)(dian)(dian)路(lu)，La和Lb就是共(gong)(gong)模(mo)(mo)電(dian)(dian)(dian)(dian)感(gan)線圈(quan)(quan)。這(zhe)兩個線圈(quan)(quan)繞(rao)在(zai)同(tong)(tong)一鐵(tie)芯上，匝數和相(xiang)位都相(xiang)同(tong)(tong)(繞(rao)制反(fan)(fan)向(xiang)(xiang))。這(zhe)樣，當電(dian)(dian)(dian)(dian)路(lu)中的(de)(de)(de)(de)正(zheng)常電(dian)(dian)(dian)(dian)流(liu)流(liu)經共(gong)(gong)模(mo)(mo)電(dian)(dian)(dian)(dian)感(gan)時，電(dian)(dian)(dian)(dian)流(liu)在(zai)同(tong)(tong)相(xiang)位繞(rao)制的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)感(gan)線圈(quan)(quan)中產(chan)生(sheng)反(fan)(fan)向(xiang)(xiang)的(de)(de)(de)(de)磁(ci)場(chang)而相(xiang)互抵消，此時正(zheng)常信號電(dian)(dian)(dian)(dian)流(liu)主(zhu)要受(shou)線圈(quan)(quan)電(dian)(dian)(dian)(dian)阻的(de)(de)(de)(de)影(ying)響(和少量因(yin)漏(lou)感(gan)造成的(de)(de)(de)(de)阻尼(ni)(ni))；當有共(gong)(gong)模(mo)(mo)電(dian)(dian)(dian)(dian)流(liu)流(liu)經線圈(quan)(quan)時，由于共(gong)(gong)模(mo)(mo)電(dian)(dian)(dian)(dian)流(liu)的(de)(de)(de)(de)同(tong)(tong)向(xiang)(xiang)性，會在(zai)線圈(quan)(quan)內(nei)產(chan)生(sheng)同(tong)(tong)向(xiang)(xiang)的(de)(de)(de)(de)磁(ci)場(chang)而增大線圈(quan)(quan)的(de)(de)(de)(de)感(gan)抗(kang)(kang)，使線圈(quan)(quan)表現為(wei)高阻抗(kang)(kang)，產(chan)生(sheng)較(jiao)強的(de)(de)(de)(de)阻尼(ni)(ni)效(xiao)果(guo)，以此衰(shuai)減共(gong)(gong)模(mo)(mo)電(dian)(dian)(dian)(dian)流(liu)，達到濾(lv)波(bo)的(de)(de)(de)(de)目的(de)(de)(de)(de)。

通常情況(kuang)下，同時注意選擇(ze)(ze)所需濾波的(de)頻段，共模阻抗(kang)越大越好，因此在選擇(ze)(ze)共模電感時需要看(kan)器件資(zi)料，主(zhu)要根據(ju)阻抗(kang)頻率曲線選擇(ze)(ze)。另外選擇(ze)(ze)時注意考慮(lv)差(cha)模阻抗(kang)對信號的(de)影(ying)響，主(zhu)要關注差(cha)模阻抗(kang)，特別注意高(gao)速端(duan)口。

文章源自：共模電感、貼片電感、貼片電感代理商