電腦電源的組成部分

1、濾波器

一個(ge)電(dian)(dian)(dian)(dian)源通常(chang)包含不(bu)止一個(ge)電(dian)(dian)(dian)(dian)磁濾(lv)波器(qi)，第一個(ge)位于市電(dian)(dian)(dian)(dian)接入(ru)電(dian)(dian)(dian)(dian)源的(de)(de)位置，可以(yi)在一個(ge)電(dian)(dian)(dian)(dian)源的(de)(de)220V市電(dian)(dian)(dian)(dian)接口背后發(fa)現它。其電(dian)(dian)(dian)(dian)路主要作用是濾(lv)除外界(jie)的(de)(de)突發(fa)脈沖和(he)高頻干擾(rao)，另一方面(mian)也會減少(shao)開(kai)關(guan)電(dian)(dian)(dian)(dian)源本(ben)身(shen)對外界(jie)的(de)(de)電(dian)(dian)(dian)(dian)磁干擾(rao)。它的(de)(de)結構雖然簡(jian)單，大(da)都由(you)X電(dian)(dian)(dian)(dian)容、Y電(dian)(dian)(dian)(dian)容和(he)變壓(ya)器(qi)型電(dian)(dian)(dian)(dian)感組(zu)成(cheng)，但卻(que)是電(dian)(dian)(dian)(dian)源中的(de)(de)重要設備(bei)，如(ru)果在這(zhe)(zhe)上面(mian)偷工減料的(de)(de)話，電(dian)(dian)(dian)(dian)源的(de)(de)屏(ping)蔽性(xing)能將(jiang)大(da)打折(zhe)扣(kou)。如(ru)果拿優質名牌(pai)電(dian)(dian)(dian)(dian)源和(he)普通雜(za)牌(pai)電(dian)(dian)(dian)(dian)源比較的(de)(de)話，會發(fa)現大(da)部分雜(za)牌(pai)電(dian)(dian)(dian)(dian)源都缺少(shao)EMI電(dian)(dian)(dian)(dian)路，電(dian)(dian)(dian)(dian)源直接從市電(dian)(dian)(dian)(dian)引入(ru)PCB。而(er)這(zhe)(zhe)一點也就成(cheng)為區分電(dian)(dian)(dian)(dian)源質量優秀與否的(de)(de)核心之一了(le)。

此外，很多品牌優質電(dian)(dian)(dian)源為保證輸入(ru)到整流電(dian)(dian)(dian)路(lu)中的電(dian)(dian)(dian)流的純凈，還(huan)都設計了第(di)二道(dao)濾波電(dian)(dian)(dian)路(lu)。此濾波電(dian)(dian)(dian)路(lu)同(tong)樣也是由X電(dian)(dian)(dian)容、Y電(dian)(dian)(dian)容和(he)變壓器型電(dian)(dian)(dian)感(gan)組(zu)成，位置位于PCB上，靠近第(di)一道(dao)EMI電(dian)(dian)(dian)路(lu)附(fu)近。

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2、保護器--壓敏電阻

壓敏電(dian)阻(zu)是(shi)(shi)每(mei)個電(dian)源必(bi)不可(ke)少的(de)元件，散布在印刷電(dian)路板（PCB）上，其作用(yong)是(shi)(shi)對電(dian)源提供保護。它的(de)原理(li)基本(ben)和家里(li)的(de)保險絲(si)類似(si)，使用(yong)自我(wo)熔斷(duan)方式切斷(duan)電(dian)流。

3、濾波電路

稍(shao)微學過一(yi)點電(dian)(dian)子電(dian)(dian)路(lu)的(de)(de)(de)人都知道：交流(liu)(liu)轉（脈沖）直流(liu)(liu)必須經(jing)過一(yi)個整流(liu)(liu)濾波電(dian)(dian)路(lu)。最(zui)常(chang)(chang)見的(de)(de)(de)就是(shi)由(you)四(si)個二(er)極(ji)管(guan)和兩個濾波電(dian)(dian)容組(zu)成的(de)(de)(de)橋(qiao)式濾波電(dian)(dian)路(lu)。計(ji)算(suan)機電(dian)(dian)源(yuan)通常(chang)(chang)都采(cai)用(yong)這種方式整流(liu)(liu)。根據封裝模式不同(tong)，計(ji)算(suan)機電(dian)(dian)源(yuan)中常(chang)(chang)見的(de)(de)(de)整流(liu)(liu)濾波電(dian)(dian)路(lu)常(chang)(chang)見的(de)(de)(de)有兩種：一(yi)種是(shi)獨立(li)四(si)個二(er)極(ji)管(guan)組(zu)成，另外(wai)一(yi)種將四(si)個二(er)極(ji)管(guan)封裝在一(yi)起，稱為“全(quan)橋(qiao)”。無論全(quan)橋(qiao)還是(shi)獨立(li)二(er)極(ji)管(guan)，所能承(cheng)受(shou)的(de)(de)(de)最(zui)低(di)耐(nai)壓和最(zui)大電(dian)(dian)流(liu)(liu)都是(shi)有限制的(de)(de)(de)：耐(nai)壓應不低(di)于700V，最(zui)大電(dian)(dian)流(liu)(liu)應不小于1A。

4、變壓器

在電(dian)(dian)源中，變(bian)壓器(qi)是將高(gao)壓轉(zhuan)(zhuan)換為低(di)壓，供電(dian)(dian)腦使用。根據電(dian)(dian)磁學原(yuan)理，變(bian)壓器(qi)的轉(zhuan)(zhuan)換比率主要由其線圈的匝數決定，因此(ci)個頭越大的開關型(xing)變(bian)壓器(qi)往往可以傳遞更(geng)多的能量(liang)，也是分(fen)辨優質或低(di)劣電(dian)(dian)源的觀(guan)察點之一(yi)，一(yi)定程度上，變(bian)壓器(qi)的個頭直接影響電(dian)(dian)源的真正輸出功率和(he)品質。

開關三極管是電源的中心(xin)樞紐，它主(zhu)要(yao)負責將轉換后的高壓(ya)(ya)直流(liu)輸(shu)送到開關變(bian)壓(ya)(ya)器(qi)上進行(xing)降壓(ya)(ya)，其耐壓(ya)(ya)程度不得小(xiao)于(yu)800V，輸(shu)出電流(liu)通(tong)常(chang)不能小(xiao)于(yu)5A。開關三極管(guan)屬于(yu)核心(xin)易損部(bu)件，又是電源(yuan)的核心(xin)部(bu)分，所以(yi)開關三極管(guan)的質量和電源(yuan)本身的品質也是息息相關的。

5、保護電路

電(dian)(dian)(dian)源(yuan)內部(bu)的(de)(de)保護電(dian)(dian)(dian)路監視著電(dian)(dian)(dian)源(yuan)的(de)(de)一(yi)舉一(yi)動，是電(dian)(dian)(dian)源(yuan)的(de)(de)大腦。它負責(ze)啟動電(dian)(dian)(dian)源(yuan)并進行(xing)電(dian)(dian)(dian)壓(ya)/電(dian)(dian)(dian)流(liu)的(de)(de)監控和調整，同時在出現(xian)短路、斷路、過壓(ya)、過流(liu)、欠(qian)壓(ya)、欠(qian)流(liu)等情況的(de)(de)時候進行(xing)自動保護。劣質(zhi)電(dian)(dian)(dian)源(yuan)通(tong)常會(hui)簡化這部(bu)分電(dian)(dian)(dian)路甚(shen)至根本不設(she)置(zhi)保護電(dian)(dian)(dian)路，而這一(yi)切都會(hui)給電(dian)(dian)(dian)腦系(xi)統帶(dai)來諸多(duo)隱患。

根據保(bao)護(hu)(hu)電(dian)路的(de)(de)位置(zhi)和(he)監(jian)(jian)控的(de)(de)類型(xing)不同，電(dian)源內部的(de)(de)保(bao)護(hu)(hu)電(dian)路又分為輸(shu)(shu)入端(duan)過(guo)(guo)壓(ya)保(bao)護(hu)(hu)、輸(shu)(shu)入端(duan)過(guo)(guo)流保(bao)護(hu)(hu)、輸(shu)(shu)出(chu)端(duan)過(guo)(guo)壓(ya)保(bao)護(hu)(hu)和(he)輸(shu)(shu)出(chu)端(duan)過(guo)(guo)流保(bao)護(hu)(hu)四個類型(xing)，這也(ye)是大(da)部分優質(zhi)品(pin)牌電(dian)源宣(xuan)傳(chuan)的(de)(de)“四重保(bao)護(hu)(hu)電(dian)路”的(de)(de)由(you)來(lai)。顧(gu)名思義，過(guo)(guo)壓(ya)/過(guo)(guo)流保(bao)護(hu)(hu)電(dian)路也(ye)就(jiu)是監(jian)(jian)視的(de)(de)輸(shu)(shu)入/輸(shu)(shu)出(chu)電(dian)壓(ya)/電(dian)流出(chu)現異常時自動生效，從而達到保(bao)護(hu)(hu)作用(yong)。

此外優質電源通常還設(she)置有輸出(chu)端(duan)短路保護。這是個(ge)非常實(shi)用(yong)的功能。

6、電路部分

在國家(jia)強制(zhi)實(shi)施的(de)(de)3C認(ren)證中，要(yao)求(qiu)電(dian)(dian)源內(nei)部(bu)必(bi)須增加一(yi)個(ge)功率因(yin)素校正電(dian)(dian)路(lu)，以(yi)減(jian)少開關電(dian)(dian)源對外部(bu)電(dian)(dian)網的(de)(de)干(gan)擾(rao)，這就是現在電(dian)(dian)源內(nei)部(bu)的(de)(de)PFC電(dian)(dian)路(lu)。所(suo)以(yi)最新(xin)通過國家(jia)CCC認(ren)證的(de)(de)電(dian)(dian)源內(nei)部(bu)都會出(chu)現一(yi)個(ge)新(xin)的(de)(de)部(bu)件，PFC電(dian)(dian)路(lu)。通過本次(ci)對數十款電(dian)(dian)源的(de)(de)拆卸(xie)，可以(yi)發現常(chang)見PFC電(dian)(dian)路(lu)其實(shi)就是一(yi)個(ge)無源電(dian)(dian)感，其成本大約在5-6元(yuan)人民(min)幣左右，個(ge)頭比開關變(bian)壓器還(huan)要(yao)大，樣子很(hen)像(xiang)開關變(bian)壓器，同樣用(yong)黃(huang)色膠帶封裝(zhuang)。還(huan)有一(yi)些追求(qiu)空間的(de)(de)緊湊型(xing)產品或者追求(qiu)性能表(biao)現的(de)(de)電(dian)(dian)源產品會使(shi)用(yong)成本在20-30元(yuan)的(de)(de)有源PFC元(yuan)器件，個(ge)頭小但是功率因(yin)數可以(yi)接近于一(yi)，效(xiao)果十分優(you)秀。

7、散熱部分

電(dian)(dian)(dian)(dian)腦(nao)電(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)的(de)(de)(de)轉換效率(lv)通(tong)常在70-80%之間，這(zhe)就(jiu)意味著20-30%的(de)(de)(de) 能量(liang)(liang)將轉化(hua)為熱(re)量(liang)(liang)。這(zhe)些(xie)熱(re)量(liang)(liang)積聚在電(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)中不能及時散發(fa)，會使電(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)局部溫度(du)過(guo)高，從而對電(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)造(zao)成不必要的(de)(de)(de)傷害(hai)。因此(ci)任何(he)電(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)內部都(dou)包(bao)含有散熱(re)裝置，由此(ci)得來的(de)(de)(de)風(feng)扇排 風(feng)量(liang)(liang)和(he)(he)噪音指數也(ye)是電(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)的(de)(de)(de)兩個(ge)重要指標。電(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)散熱(re)主要通(tong)過(guo)散熱(re)片和(he)(he)功率(lv)管(guan)配合(he)進行(xing)，從縫隙中望進去，都(dou)能看(kan)到電(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)內部有巨大(da)(da)的(de)(de)(de)散熱(re)片，上(shang)面的(de)(de)(de)大(da)(da)功率(lv)管(guan) 的(de)(de)(de)性能和(he)(he)極限參(can)數直接影響到電(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)的(de)(de)(de)安(an)全承載功率(lv)和(he)(he)產品成本，也(ye)與電(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)的(de)(de)(de)余量(liang)(liang)大(da)(da)小密切相關。所以(yi)說觀察散熱(re)片和(he)(he)上(shang)面的(de)(de)(de)功率(lv)管(guan)也(ye)是判斷一個(ge)電(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)好與壞(huai)的(de)(de)(de)方(fang)法(fa)。