電腦電源的組成部分

1、濾波器

一(yi)個電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)通(tong)常包含(han)不止(zhi)一(yi)個電(dian)(dian)(dian)(dian)(dian)磁(ci)濾(lv)波器(qi)(qi)，第一(yi)個位(wei)于市(shi)電(dian)(dian)(dian)(dian)(dian)接入(ru)(ru)電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)的(de)(de)(de)位(wei)置，可以在(zai)一(yi)個電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)的(de)(de)(de)220V市(shi)電(dian)(dian)(dian)(dian)(dian)接口背(bei)后發(fa)現它。其電(dian)(dian)(dian)(dian)(dian)路(lu)主(zhu)要作用是(shi)濾(lv)除外(wai)界的(de)(de)(de)突(tu)發(fa)脈沖和(he)高頻(pin)干(gan)擾，另一(yi)方面也會(hui)減(jian)少開關(guan)電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)本身對外(wai)界的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)磁(ci)干(gan)擾。它的(de)(de)(de)結構雖然(ran)簡單，大(da)都(dou)由X電(dian)(dian)(dian)(dian)(dian)容、Y電(dian)(dian)(dian)(dian)(dian)容和(he)變壓器(qi)(qi)型電(dian)(dian)(dian)(dian)(dian)感組成(cheng)，但卻是(shi)電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)中的(de)(de)(de)重要設(she)備(bei)，如(ru)果(guo)在(zai)這上面偷工(gong)減(jian)料(liao)的(de)(de)(de)話(hua)，電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)的(de)(de)(de)屏蔽(bi)性(xing)能將大(da)打(da)折扣(kou)。如(ru)果(guo)拿(na)優(you)質名牌(pai)電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)和(he)普通(tong)雜(za)牌(pai)電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)比(bi)較的(de)(de)(de)話(hua)，會(hui)發(fa)現大(da)部分雜(za)牌(pai)電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)都(dou)缺少EMI電(dian)(dian)(dian)(dian)(dian)路(lu)，電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)直接從市(shi)電(dian)(dian)(dian)(dian)(dian)引入(ru)(ru)PCB。而這一(yi)點也就成(cheng)為區(qu)分電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)質量優(you)秀(xiu)與(yu)否的(de)(de)(de)核心之一(yi)了。

此外，很多品(pin)牌優(you)質電源為(wei)保(bao)證輸入到整流電路(lu)中(zhong)的(de)電流的(de)純凈，還都設計了第(di)(di)二道濾(lv)波電路(lu)。此濾(lv)波電路(lu)同樣(yang)也是由X電容、Y電容和變壓(ya)器型電感組成，位置位于(yu)PCB上，靠近(jin)第(di)(di)一道EMI電路(lu)附近(jin)。

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2、保護器--壓敏電阻

壓敏電(dian)(dian)阻是(shi)每個電(dian)(dian)源必不可(ke)少的元件，散布在印刷(shua)電(dian)(dian)路板（PCB）上(shang)，其作用是(shi)對(dui)電(dian)(dian)源提供保(bao)護。它的原理(li)基(ji)本(ben)和家里的保(bao)險絲類似，使(shi)用自(zi)我熔斷方式切(qie)斷電(dian)(dian)流。

3、濾波電路

稍微學過(guo)一(yi)點(dian)電(dian)(dian)(dian)(dian)子電(dian)(dian)(dian)(dian)路(lu)的(de)(de)人(ren)都(dou)(dou)知道(dao)：交流(liu)轉（脈沖）直(zhi)流(liu)必(bi)須(xu)經過(guo)一(yi)個(ge)整流(liu)濾波(bo)(bo)電(dian)(dian)(dian)(dian)路(lu)。最常(chang)(chang)見(jian)的(de)(de)就是(shi)由四(si)個(ge)二(er)極(ji)(ji)管(guan)(guan)和(he)兩個(ge)濾波(bo)(bo)電(dian)(dian)(dian)(dian)容組成(cheng)的(de)(de)橋式(shi)濾波(bo)(bo)電(dian)(dian)(dian)(dian)路(lu)。計算(suan)機電(dian)(dian)(dian)(dian)源(yuan)通常(chang)(chang)都(dou)(dou)采用這種(zhong)(zhong)方式(shi)整流(liu)。根據封裝模式(shi)不同(tong)，計算(suan)機電(dian)(dian)(dian)(dian)源(yuan)中常(chang)(chang)見(jian)的(de)(de)整流(liu)濾波(bo)(bo)電(dian)(dian)(dian)(dian)路(lu)常(chang)(chang)見(jian)的(de)(de)有兩種(zhong)(zhong)：一(yi)種(zhong)(zhong)是(shi)獨(du)立四(si)個(ge)二(er)極(ji)(ji)管(guan)(guan)組成(cheng)，另外一(yi)種(zhong)(zhong)將四(si)個(ge)二(er)極(ji)(ji)管(guan)(guan)封裝在一(yi)起，稱為“全橋”。無論全橋還是(shi)獨(du)立二(er)極(ji)(ji)管(guan)(guan)，所能承受的(de)(de)最低耐(nai)壓和(he)最大(da)電(dian)(dian)(dian)(dian)流(liu)都(dou)(dou)是(shi)有限制的(de)(de)：耐(nai)壓應不低于700V，最大(da)電(dian)(dian)(dian)(dian)流(liu)應不小于1A。

4、變壓器

在電源(yuan)中，變(bian)壓(ya)(ya)器是將高壓(ya)(ya)轉換(huan)為低(di)壓(ya)(ya)，供電腦使用。根(gen)據電磁學原理，變(bian)壓(ya)(ya)器的(de)(de)轉換(huan)比率(lv)主要由其線圈的(de)(de)匝數決定(ding)，因此(ci)個(ge)頭(tou)越(yue)大的(de)(de)開關型變(bian)壓(ya)(ya)器往往可(ke)以(yi)傳遞更多的(de)(de)能量，也是分辨優質(zhi)或低(di)劣(lie)電源(yuan)的(de)(de)觀察(cha)點之(zhi)一，一定(ding)程度上，變(bian)壓(ya)(ya)器的(de)(de)個(ge)頭(tou)直接影響(xiang)電源(yuan)的(de)(de)真正輸出功率(lv)和品質(zhi)。

開關三極管是電源的(de)(de)中(zhong)心樞紐，它主(zhu)要負責將轉換后的(de)(de)高壓(ya)直(zhi)流(liu)輸送到開關(guan)變壓(ya)器上進行降壓(ya)，其耐壓(ya)程(cheng)度不得小(xiao)于(yu)800V，輸出電流(liu)通(tong)常不能(neng)小(xiao)于(yu)5A。開關(guan)三極管屬于(yu)核(he)心易損部件，又是電源(yuan)(yuan)的(de)(de)核(he)心部分，所(suo)以開關(guan)三極管的(de)(de)質量和電源(yuan)(yuan)本身(shen)的(de)(de)品質也是息息相關(guan)的(de)(de)。

5、保護電路

電源(yuan)內部的(de)保護電路(lu)(lu)監視著(zhu)電源(yuan)的(de)一(yi)舉一(yi)動(dong)，是電源(yuan)的(de)大腦。它負責啟動(dong)電源(yuan)并進(jin)行電壓/電流的(de)監控和調整，同時(shi)在(zai)出(chu)現短路(lu)(lu)、斷路(lu)(lu)、過壓、過流、欠壓、欠流等情(qing)況的(de)時(shi)候進(jin)行自動(dong)保護。劣質電源(yuan)通常會簡化這(zhe)部分(fen)電路(lu)(lu)甚(shen)至根本不設(she)置保護電路(lu)(lu)，而(er)這(zhe)一(yi)切都會給(gei)電腦系統帶(dai)來諸多(duo)隱患。

根據保(bao)護(hu)(hu)(hu)電(dian)(dian)(dian)路(lu)(lu)的(de)(de)位置(zhi)和監(jian)控的(de)(de)類型不(bu)同，電(dian)(dian)(dian)源(yuan)內部的(de)(de)保(bao)護(hu)(hu)(hu)電(dian)(dian)(dian)路(lu)(lu)又分為輸(shu)(shu)入(ru)(ru)(ru)端過(guo)(guo)(guo)(guo)壓(ya)保(bao)護(hu)(hu)(hu)、輸(shu)(shu)入(ru)(ru)(ru)端過(guo)(guo)(guo)(guo)流保(bao)護(hu)(hu)(hu)、輸(shu)(shu)出(chu)端過(guo)(guo)(guo)(guo)壓(ya)保(bao)護(hu)(hu)(hu)和輸(shu)(shu)出(chu)端過(guo)(guo)(guo)(guo)流保(bao)護(hu)(hu)(hu)四(si)(si)個類型，這也(ye)是大部分優質品牌電(dian)(dian)(dian)源(yuan)宣傳的(de)(de)“四(si)(si)重保(bao)護(hu)(hu)(hu)電(dian)(dian)(dian)路(lu)(lu)”的(de)(de)由來。顧名思義(yi)，過(guo)(guo)(guo)(guo)壓(ya)/過(guo)(guo)(guo)(guo)流保(bao)護(hu)(hu)(hu)電(dian)(dian)(dian)路(lu)(lu)也(ye)就是監(jian)視的(de)(de)輸(shu)(shu)入(ru)(ru)(ru)/輸(shu)(shu)出(chu)電(dian)(dian)(dian)壓(ya)/電(dian)(dian)(dian)流出(chu)現(xian)異(yi)常時(shi)自動生效，從(cong)而達到保(bao)護(hu)(hu)(hu)作用(yong)。

此(ci)外優質電源通常(chang)還設置有(you)輸出端短路保護。這(zhe)是個(ge)非(fei)常(chang)實用的功能。

6、電路部分

在國(guo)家強制實施的3C認證中，要求電源(yuan)內部(bu)必(bi)須增(zeng)加一(yi)個功率因素(su)校正電路，以減少開(kai)關(guan)(guan)電源(yuan)對(dui)外(wai)部(bu)電網的干(gan)擾，這(zhe)就是現(xian)在電源(yuan)內部(bu)的PFC電路。所(suo)以最(zui)新通(tong)過(guo)國(guo)家CCC認證的電源(yuan)內部(bu)都會出現(xian)一(yi)個新的部(bu)件(jian)，PFC電路。通(tong)過(guo)本次對(dui)數十款電源(yuan)的拆卸(xie)，可(ke)以發現(xian)常(chang)見PFC電路其實就是一(yi)個無源(yuan)電感，其成本大(da)約在5-6元(yuan)人民(min)幣左(zuo)右，個頭(tou)比(bi)開(kai)關(guan)(guan)變(bian)壓(ya)器(qi)還要大(da)，樣子很像開(kai)關(guan)(guan)變(bian)壓(ya)器(qi)，同(tong)樣用(yong)黃色膠帶封(feng)裝。還有一(yi)些追(zhui)求空間的緊(jin)湊型(xing)產(chan)品(pin)(pin)或者追(zhui)求性能表現(xian)的電源(yuan)產(chan)品(pin)(pin)會使(shi)用(yong)成本在20-30元(yuan)的有源(yuan)PFC元(yuan)器(qi)件(jian)，個頭(tou)小但(dan)是功率因數可(ke)以接近于一(yi)，效果十分優秀。

7、散熱部分

電(dian)(dian)腦(nao)電(dian)(dian)源的(de)(de)轉(zhuan)換效(xiao)率(lv)(lv)通常(chang)在70-80%之(zhi)間，這就(jiu)意味著(zhu)20-30%的(de)(de) 能量(liang)(liang)將(jiang)轉(zhuan)化為熱量(liang)(liang)。這些熱量(liang)(liang)積(ji)聚(ju)在電(dian)(dian)源中不(bu)(bu)能及時(shi)散(san)(san)發，會使電(dian)(dian)源局部(bu)(bu)(bu)溫度過高(gao)，從(cong)而對電(dian)(dian)源造成不(bu)(bu)必要(yao)的(de)(de)傷害。因此(ci)任(ren)何電(dian)(dian)源內(nei)部(bu)(bu)(bu)都(dou)包含有散(san)(san)熱裝(zhuang)置，由此(ci)得來(lai)的(de)(de)風(feng)扇(shan)排(pai) 風(feng)量(liang)(liang)和噪音(yin)指(zhi)數也(ye)是電(dian)(dian)源的(de)(de)兩個重(zhong)要(yao)指(zhi)標。電(dian)(dian)源散(san)(san)熱主要(yao)通過散(san)(san)熱片和功(gong)(gong)率(lv)(lv)管(guan)配合進(jin)行，從(cong)縫隙中望進(jin)去，都(dou)能看到電(dian)(dian)源內(nei)部(bu)(bu)(bu)有巨大(da)的(de)(de)散(san)(san)熱片，上面的(de)(de)大(da)功(gong)(gong)率(lv)(lv)管(guan) 的(de)(de)性能和極(ji)限(xian)參數直接影響到電(dian)(dian)源的(de)(de)安全承載功(gong)(gong)率(lv)(lv)和產品成本，也(ye)與電(dian)(dian)源的(de)(de)余量(liang)(liang)大(da)小密切(qie)相關。所以說(shuo)觀察散(san)(san)熱片和上面的(de)(de)功(gong)(gong)率(lv)(lv)管(guan)也(ye)是判(pan)斷(duan)一(yi)個電(dian)(dian)源好與壞的(de)(de)方法。