線性電源和開關電源的優缺點
2019/6/28 10:29:32??????點擊:
都是直流電 按要(yao)求(qiu)不同使(shi)用(yong)不同 ,線(xian)性(xing)電源最好 他(ta)輸(shu)出(chu)(chu)的(de)是線(xian)性(xing)直流電,可以用(yong)在要(yao)求(qiu)高(gao)(gao)的(de)場合(he),開關(guan)電源次之,他(ta)是由很高(gao)(gao)的(de)開關(guan)速度的(de)變壓器和開關(guan)管,特(te)點是重量小,容(rong)量大(da),輸(shu)出(chu)(chu)質(zhi)量高(gao)(gao),相控電原用(yong)在要(yao)求(qiu)不高(gao)(gao),電流特(te)大(da)的(de)場合(he)
線性電(dian)源(yuan),開關電(dian)源(yuan)區別
線性電(dian)源(yuan)的(de)調(diao)整管(guan)工作在(zai)放大(da)狀態,因而(er)發熱量大(da),效率低(35%左右(you)),需(xu)要(yao)加體積龐大(da)的(de)散熱片(pian),而(er)且還需(xu)要(yao)同樣(yang)也是大(da)體積的(de)工頻變壓器(qi),當(dang)要(yao)制作多組電(dian)壓輸(shu)出(chu)時變壓器(qi)會更龐大(da)。
開(kai)(kai)關(guan)(guan)電(dian)源的調整(zheng)管工(gong)作(zuo)在(zai)(zai)飽和(he)和(he)截至(zhi)狀(zhuang)態,因(yin)而(er)發熱量小(xiao)(xiao),效(xiao)率高(75%以(yi)上)而(er)且省掉了大體(ti)積的變壓器。但(dan)開(kai)(kai)關(guan)(guan)電(dian)源輸出的直流(liu)上面會疊(die)加較大的紋(wen)波(50mV at 5V output typical),在(zai)(zai)輸出端并接穩(wen)壓二極管可以(yi)改(gai)善,另外由(you)于開(kai)(kai)關(guan)(guan)管工(gong)作(zuo)是(shi)會產生很大的尖峰脈沖干擾,也需要在(zai)(zai)電(dian)路中串連磁珠(zhu)加以(yi)改(gai)善。相(xiang)對而(er)言線(xian)性電(dian)源就沒有以(yi)上缺陷,它的紋(wen)波可以(yi)做的很小(xiao)(xiao)(5mV以(yi)下)。
對于電(dian)源(yuan)(yuan)效率(lv)和安裝體積有要求的地方用(yong)開(kai)關(guan)電(dian)源(yuan)(yuan)為佳(jia),對于電(dian)磁(ci)干擾和電(dian)源(yuan)(yuan)純凈性有要求的地方(例如電(dian)容漏電(dian)檢測)多(duo)選用(yong)線性電(dian)源(yuan)(yuan)。另外當(dang)電(dian)路(lu)中需要作(zuo)隔離的時候現在多(duo)數(shu)用(yong)DC-DC來(lai)做對隔離部分供電(dian)(DC-DC從其工作(zuo)原(yuan)理上來(lai)說就是開(kai)關(guan)電(dian)源(yuan)(yuan))。還有,開(kai)關(guan)電(dian)源(yuan)(yuan)中用(yong)到的高頻(pin)變壓器可能繞制起來(lai)比(bi)較麻煩
開(kai)(kai)關(guan)電(dian)(dian)源和線性電(dian)(dian)源在(zai)內(nei)部結(jie)構上是(shi)(shi)完全不一樣的(de)(de)(de),開(kai)(kai)關(guan)電(dian)(dian)源顧名(ming)思義(yi)有開(kai)(kai)關(guan)動(dong)作,它利用變占空比或(huo)變頻的(de)(de)(de)方法實(shi)(shi)現不同的(de)(de)(de)電(dian)(dian)壓,實(shi)(shi)現較為復(fu)雜(za),最大的(de)(de)(de)優(you)點(dian)是(shi)(shi)高(gao)(gao)效率,一般(ban)在(zai)90%以上,缺點(dian)是(shi)(shi)文波(bo)和開(kai)(kai)關(guan)噪聲(sheng)(sheng)較大,適(shi)用于對文波(bo)和噪聲(sheng)(sheng)要(yao)求不高(gao)(gao)的(de)(de)(de)場合(he);而線性電(dian)(dian)源沒有開(kai)(kai)關(guan)動(dong)作,屬(shu)于連續模(mo)擬控制,內(nei)部結(jie)構相(xiang)對簡(jian)單,芯片(pian)面(mian)積也較小,成本(ben)較低(di),優(you)點(dian)是(shi)(shi)成本(ben)低(di),文波(bo)噪聲(sheng)(sheng)小,最大的(de)(de)(de)缺點(dian)是(shi)(shi)效率低(di)。它們各有有缺點(dian)在(zai)應用上互補共存!
一、線性電源的原理:
線(xian)性電(dian)(dian)(dian)(dian)(dian)源(yuan)主要包括工頻(pin)變壓(ya)(ya)(ya)(ya)器(qi)、輸出(chu)整(zheng)流(liu)濾波(bo)(bo)器(qi)、控制電(dian)(dian)(dian)(dian)(dian)路、保護(hu)電(dian)(dian)(dian)(dian)(dian)路等。 線(xian)性電(dian)(dian)(dian)(dian)(dian)源(yuan)是(shi)先將(jiang)交流(liu)電(dian)(dian)(dian)(dian)(dian)經(jing)過(guo)變壓(ya)(ya)(ya)(ya)器(qi)變壓(ya)(ya)(ya)(ya),再經(jing)過(guo)整(zheng)流(liu)電(dian)(dian)(dian)(dian)(dian)路整(zheng)流(liu)濾波(bo)(bo)得到未穩(wen)定的(de)直(zhi)流(liu)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya),要達(da)到高精(jing)度(du)的(de)直(zhi)流(liu)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya),必須(xu)經(jing)過(guo)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)反(fan)饋調整(zheng)輸出(chu)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya),這(zhe)種電(dian)(dian)(dian)(dian)(dian)源(yuan)技術很成熟,可以(yi)達(da)到很高的(de)穩(wen)定度(du),波(bo)(bo)紋(wen)也很小,而且(qie)沒有開關(guan)電(dian)(dian)(dian)(dian)(dian)源(yuan)具有的(de)干擾與噪音。但是(shi)它的(de)缺點是(shi)需(xu)要龐大(da)(da)而笨重的(de)變壓(ya)(ya)(ya)(ya)器(qi),所(suo)需(xu)的(de)濾波(bo)(bo)電(dian)(dian)(dian)(dian)(dian)容的(de)體積和重量(liang)也相當大(da)(da),而且(qie)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)反(fan)饋電(dian)(dian)(dian)(dian)(dian)路是(shi)工作在(zai)線(xian)性狀態,調整(zheng)管(guan)上有一定的(de)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)降,在(zai)輸出(chu)較大(da)(da)工作電(dian)(dian)(dian)(dian)(dian)流(liu)時,致(zhi)使調整(zheng)管(guan)的(de)功耗太大(da)(da),轉換效率低,還(huan)要安裝很大(da)(da)的(de)散(san)熱片。這(zhe)種電(dian)(dian)(dian)(dian)(dian)源(yuan)不適合計算機等設備的(de)需(xu)要,將(jiang)逐步被(bei)開關(guan)電(dian)(dian)(dian)(dian)(dian)源(yuan)所(suo)取代。
二(er)、開關(guan)電源的原理:
開關電(dian)源主要包括輸入電(dian)網濾(lv)波(bo)器、輸入整流濾(lv)波(bo)器、逆變(bian)器、輸出整流濾(lv)波(bo)器、控制電(dian)路、保護電(dian)路。它們(men)的(de)功能是:
1、輸入電網(wang)(wang)濾波器(qi):消除(chu)來自電網(wang)(wang),如電動(dong)機(ji)的啟動(dong)、電器(qi)的開關、雷擊等產(chan)生(sheng)(sheng)的干擾,同時也防止(zhi)開關電源產(chan)生(sheng)(sheng)的高(gao)頻噪(zao)聲向電網(wang)(wang)擴散。
2、輸入整(zheng)流濾波器(qi):將(jiang)電網輸入電壓進行(xing)整(zheng)流濾波,為(wei)變換器(qi)提供直流電壓。
3、逆變器:是(shi)開關電源的關鍵部(bu)分。它把(ba)直(zhi)流電壓變換(huan)成(cheng)高頻交流電壓,并且起到將輸出部(bu)分與輸入電網(wang)隔離(li)的作用。
4、輸(shu)出整(zheng)(zheng)流濾波器(qi):將變換器(qi)輸(shu)出的高頻交流電(dian)壓整(zheng)(zheng)流濾波得到需(xu)要的直流電(dian)壓,同時還防止高頻噪聲對負(fu)載的干擾(rao)。
5、控制電(dian)(dian)路:檢測輸出(chu)直(zhi)流(liu)電(dian)(dian)壓(ya)(ya)(ya),并(bing)將其與基準(zhun)電(dian)(dian)壓(ya)(ya)(ya)比較,進(jin)行放大。調制振(zhen)蕩器的脈沖寬度,從(cong)而控制變換器以保持輸出(chu)電(dian)(dian)壓(ya)(ya)(ya)的穩定(ding)。
6、保(bao)(bao)護電(dian)路:當(dang)開關電(dian)源發生過(guo)電(dian)壓、過(guo)電(dian)流短路時,保(bao)(bao)護電(dian)路使開關電(dian)源停止工作以保(bao)(bao)護負載和電(dian)源本身。
開(kai)(kai)關(guan)電(dian)(dian)(dian)源(yuan)是將(jiang)交(jiao)流(liu)(liu)電(dian)(dian)(dian)先整(zheng)流(liu)(liu)成(cheng)直(zhi)流(liu)(liu)電(dian)(dian)(dian),在(zai)將(jiang)直(zhi)流(liu)(liu)逆變(bian)成(cheng)交(jiao)流(liu)(liu)電(dian)(dian)(dian),在(zai)整(zheng)流(liu)(liu)輸(shu)出成(cheng)所需(xu)要(yao)的(de)直(zhi)流(liu)(liu)電(dian)(dian)(dian)壓(ya)。這(zhe)樣(yang)開(kai)(kai)關(guan)電(dian)(dian)(dian)源(yuan)省去下線(xian)性電(dian)(dian)(dian)源(yuan)中(zhong)(zhong)的(de)變(bian)壓(ya)器,以及電(dian)(dian)(dian)壓(ya)反饋電(dian)(dian)(dian)路(lu)。而開(kai)(kai)關(guan)電(dian)(dian)(dian)源(yuan)中(zhong)(zhong)的(de)逆變(bian)電(dian)(dian)(dian)路(lu)完全是數字調(diao)整(zheng),同樣(yang)能(neng)達(da)到(dao)非常高的(de)調(diao)整(zheng)精度。
開關電源的主要優(you)點:
體(ti)積(ji)小、重(zhong)量(liang)輕(體(ti)積(ji)和重(zhong)量(liang)只有線(xian)性(xing)(xing)(xing)電(dian)(dian)源的(de)20~30%)、效(xiao)率高(一般為60~70%,而線(xian)性(xing)(xing)(xing)電(dian)(dian)源只有30~40%)、自身(shen)抗干擾性(xing)(xing)(xing)強(qiang)、輸出電(dian)(dian)壓范(fan)圍寬、模塊(kuai)化(hua)。
開關電源的主要缺點:
由于逆變電(dian)路中(zhong)會(hui)產生(sheng)高頻(pin)電(dian)壓,對周圍(wei)設備(bei)有一(yi)定的(de)(de)干擾(rao)。需要良(liang)好(hao)的(de)(de)屏蔽及接地
開(kai)關(guan)電(dian)(dian)(dian)源就是用(yong)通(tong)過電(dian)(dian)(dian)路控(kong)制開(kai)關(guan)管(guan)進行(xing)高(gao)速的(de)道通(tong)與(yu)截(jie)止(zhi).將直流(liu)電(dian)(dian)(dian)轉化為(wei)高(gao)頻(pin)率(lv)的(de)交(jiao)流(liu)電(dian)(dian)(dian)提供給變(bian)(bian)壓(ya)器進行(xing)變(bian)(bian)壓(ya),從而產(chan)生所需要(yao)的(de)一(yi)組或多(duo)組電(dian)(dian)(dian)壓(ya)!轉華為(wei)高(gao)頻(pin)交(jiao)流(liu)電(dian)(dian)(dian)的(de)原因是高(gao)頻(pin)交(jiao)流(liu)在變(bian)(bian)壓(ya)器變(bian)(bian)壓(ya)電(dian)(dian)(dian)路中的(de)效率(lv)要(yao)比(bi)50Hz高(gao)很(hen)多(duo).所以開(kai)關(guan)變(bian)(bian)壓(ya)器可以做的(de)很(hen)小(xiao),而且工作時不(bu)(bu)是很(hen)熱!!成(cheng)本很(hen)低.如果不(bu)(bu)將50Hz變(bian)(bian)為(wei)高(gao)頻(pin)那開(kai)關(guan)電(dian)(dian)(dian)源就沒有意義!!開(kai)關(guan)變(bian)(bian)壓(ya)器也(ye)不(bu)(bu)神秘.就是一(yi)個普通(tong)的(de)變(bian)(bian)壓(ya)器!這就是開(kai)關(guan)電(dian)(dian)(dian)源。
開關電(dian)源(yuan),是通(tong)過(guo)電(dian)子技術實現的,主要環節:整流成直流電(dian)——逆變(bian)成所(suo)需(xu)電(dian)壓的交(jiao)流電(dian)(主要來調整電(dian)壓)——再經過(guo)整流成直流電(dian)壓輸出。
開關電源的結(jie)構中由于中間(jian)沒有變(bian)壓(ya)器和散(san)熱片,因而體(ti)積非(fei)(fei)常小。同時,開關電源內部(bu)都是(shi)電子元件,效率(lv)高、發(fa)熱小。雖然,具有電磁(ci)干擾等缺點,但現在的屏蔽(bi)技術(shu)已經(jing)非(fei)(fei)常到位(wei)。
開(kai)關(guan)電源大體(ti)可以(yi)分(fen)為隔(ge)(ge)(ge)離和非隔(ge)(ge)(ge)離兩種,隔(ge)(ge)(ge)離型的(de)必(bi)定(ding)有開(kai)關(guan)變壓器(qi),而非隔(ge)(ge)(ge)離的(de)未必(bi)一定(ding)有。
簡單地(di)說,開(kai)關(guan)電源(yuan)的工作原理是:
1.交流(liu)電源輸入經整流(liu)濾波成直流(liu);
2.通過(guo)高頻PWM(脈(mo)沖寬度調制(zhi))信號控制(zhi)開關管,將那個(ge)直流(liu)加到開關變壓(ya)器初(chu)級上(shang);
3.開關變壓(ya)器(qi)次級感應出高(gao)頻電壓(ya),經整流濾波供給負載;
4.輸出部分通過一定的電路(lu)反饋給控制電路(lu),控制PWM占空比,以達到穩定輸出的目(mu)的.
交流電(dian)(dian)源(yuan)輸入時一般要經過(guo)厄(e)流圈(quan)一類的(de)東西,過(guo)濾(lv)掉(diao)電(dian)(dian)網上(shang)的(de)干擾(rao),同(tong)時也過(guo)濾(lv)掉(diao)電(dian)(dian)源(yuan)對(dui)電(dian)(dian)網的(de)干擾(rao);在(zai)功率相同(tong)時,開(kai)(kai)關頻率越高(gao),開(kai)(kai)關變(bian)壓器的(de)體積(ji)就(jiu)越小,但對(dui)開(kai)(kai)關管的(de)要求就(jiu)越高(gao);開(kai)(kai)關變(bian)壓器的(de)次(ci)級可(ke)以(yi)有多個(ge)繞(rao)(rao)組或一個(ge)繞(rao)(rao)組有多個(ge)抽頭,以(yi)得(de)到需要的(de)輸出;一般還應該(gai)增加一些保護電(dian)(dian)路(lu),比如(ru)空載、短(duan)路(lu)等(deng)保護,否則可(ke)能會燒毀開(kai)(kai)關電(dian)(dian)源(yuan)。
以上說的(de)就是開關(guan)電源的(de)大致工(gong)作原(yuan)理。
其實現在(zai)已經有了集(ji)成(cheng)度(du)非常高的專用芯片,可(ke)以使外圍電(dian)路(lu)非常簡單,甚至(zhi)做到免調試(shi)。
例如TOP系列的開關電源芯片(或稱模塊),只要配合(he)一些阻容(rong)元(yuan)件(jian),和一個(ge)開關變(bian)壓器,就可以做(zuo)成一個(ge)基本的開關電源。
開關電(dian)源&線性電(dian)源
開(kai)(kai)關電(dian)源(yuan)的(de)主要工(gong)作原(yuan)理就是上(shang)(shang)橋(qiao)和下橋(qiao)的(de)Mos管(guan)輪流(liu)導(dao)通,首(shou)先電(dian)流(liu)通過上(shang)(shang)橋(qiao)Mos管(guan)流(liu)入,利用線(xian)(xian)圈(quan)的(de)存儲功能,將電(dian)能集聚在線(xian)(xian)圈(quan)中(zhong),最后關閉上(shang)(shang)橋(qiao)Mos管(guan),打開(kai)(kai)下橋(qiao)的(de)Mos管(guan),線(xian)(xian)圈(quan)和電(dian)容持續給外部(bu)供電(dian)。然后又(you)關閉下橋(qiao)Mos管(guan),再打開(kai)(kai)上(shang)(shang)橋(qiao)讓(rang)電(dian)流(liu)進(jin)入,就這樣(yang)重復進(jin)行,因為(wei)要輪流(liu)開(kai)(kai)關Mos管(guan),所以(yi)稱為(wei)開(kai)(kai)關電(dian)源(yuan)。
而(er)線(xian)性(xing)電(dian)(dian)源(yuan)就不一樣(yang)了,由于沒有(you)(you)開(kai)關介(jie)入,使得上水管一直在放水,如(ru)果有(you)(you)多(duo)的(de)(de),就會漏出(chu)來,這(zhe)就是我們經常(chang)看到的(de)(de)某些線(xian)性(xing)電(dian)(dian)源(yuan)的(de)(de)Mos管發(fa)熱(re)量很大(da),用不完(wan)的(de)(de)電(dian)(dian)能,全部轉換成了熱(re)能。從這(zhe)個角度來看,線(xian)性(xing)電(dian)(dian)源(yuan)的(de)(de)轉換效率就非常(chang)低了,而(er)且熱(re)量高(gao)的(de)(de)時候,元件的(de)(de)壽命(ming)勢(shi)必要下降,影響最終的(de)(de)使用效果 。
開關電源和線性電源的區別主要(yao)是(shi)他(ta)們的工作方式。
線性(xing)電(dian)源功(gong)率(lv)器(qi)件工(gong)作(zuo)在線性(xing)狀態,也(ye)(ye)就(jiu)是(shi)說他(ta)(ta)一用起來功(gong)率(lv)器(qi)件就(jiu)是(shi)一直在工(gong)作(zuo),所以也(ye)(ye)就(jiu)導致他(ta)(ta)的(de)(de)工(gong)作(zuo)效(xiao)率(lv)低,一般(ban)在50%~60%,還得說他(ta)(ta)是(shi)很(hen)好的(de)(de)線性(xing)電(dian)源。線性(xing)電(dian)源的(de)(de)工(gong)作(zuo)方式(shi),使他(ta)(ta)從高壓變低壓必須(xu)有將壓裝置(zhi),一般(ban)的(de)(de)都是(shi)變壓器(qi),也(ye)(ye)有別的(de)(de)像(xiang)KX電(dian)源,再經(jing)過整(zheng)流輸出直流電(dian)壓。這樣一來他(ta)(ta)的(de)(de)體(ti)積(ji)也(ye)(ye)就(jiu)很(hen)大(da)(da),笨重,效(xiao)率(lv)低、發熱量(liang)也(ye)(ye)大(da)(da)。他(ta)(ta)也(ye)(ye)有他(ta)(ta)的(de)(de)優(you)點:紋波小(xiao),調整(zheng)率(lv)好,對外干擾小(xiao)。適合用與(yu)模(mo)擬電(dian)路,各(ge)類放大(da)(da)器(qi)等。
開(kai)關(guan)(guan)(guan)電(dian)源(yuan)。他(ta)的功(gong)率(lv)器件工作在(zai)開(kai)關(guan)(guan)(guan)狀態,(一(yi)開(kai)一(yi)關(guan)(guan)(guan),一(yi)開(kai)一(yi)關(guan)(guan)(guan),頻率(lv)非(fei)常(chang)快(kuai),一(yi)般的平板開(kai)關(guan)(guan)(guan)電(dian)源(yuan)頻率(lv)在(zai)100~200KHz,模(mo)塊電(dian)源(yuan)在(zai)300~500KHZ).這樣(yang)他(ta)的損耗就小(xiao),效(xiao)(xiao)率(lv)也就高,對變壓器也有了要求(qiu),要用高磁導(dao)率(lv)的材料來(lai)做(zuo).有點墨跡(ji)了,他(ta)的變壓器就是(shi)一(yi)個字(zi)小(xiao).效(xiao)(xiao)率(lv)80%~90%吧.據說美國最好的VICOR模(mo)塊高達99%.開(kai)關(guan)(guan)(guan)電(dian)源(yuan)的效(xiao)(xiao)率(lv)高體(ti)積(ji)小(xiao),但(dan)是(shi)和線(xian)性電(dian)源(yuan)比他(ta)的紋波(bo),電(dian)壓電(dian)流(liu)調整率(lv)就有折扣了 。
線性電(dian)源(yuan),開關電(dian)源(yuan)區別
線性電(dian)源(yuan)的(de)調(diao)整管(guan)工作在(zai)放大(da)狀態,因而(er)發熱量大(da),效率低(35%左右(you)),需(xu)要(yao)加體積龐大(da)的(de)散熱片(pian),而(er)且還需(xu)要(yao)同樣(yang)也是大(da)體積的(de)工頻變壓器(qi),當(dang)要(yao)制作多組電(dian)壓輸(shu)出(chu)時變壓器(qi)會更龐大(da)。
開(kai)(kai)關(guan)(guan)電(dian)源的調整(zheng)管工(gong)作(zuo)在(zai)(zai)飽和(he)和(he)截至(zhi)狀(zhuang)態,因(yin)而(er)發熱量小(xiao)(xiao),效(xiao)率高(75%以(yi)上)而(er)且省掉了大體(ti)積的變壓器。但(dan)開(kai)(kai)關(guan)(guan)電(dian)源輸出的直流(liu)上面會疊(die)加較大的紋(wen)波(50mV at 5V output typical),在(zai)(zai)輸出端并接穩(wen)壓二極管可以(yi)改(gai)善,另外由(you)于開(kai)(kai)關(guan)(guan)管工(gong)作(zuo)是(shi)會產生很大的尖峰脈沖干擾,也需要在(zai)(zai)電(dian)路中串連磁珠(zhu)加以(yi)改(gai)善。相(xiang)對而(er)言線(xian)性電(dian)源就沒有以(yi)上缺陷,它的紋(wen)波可以(yi)做的很小(xiao)(xiao)(5mV以(yi)下)。
對于電(dian)源(yuan)(yuan)效率(lv)和安裝體積有要求的地方用(yong)開(kai)關(guan)電(dian)源(yuan)(yuan)為佳(jia),對于電(dian)磁(ci)干擾和電(dian)源(yuan)(yuan)純凈性有要求的地方(例如電(dian)容漏電(dian)檢測)多(duo)選用(yong)線性電(dian)源(yuan)(yuan)。另外當(dang)電(dian)路(lu)中需要作(zuo)隔離的時候現在多(duo)數(shu)用(yong)DC-DC來(lai)做對隔離部分供電(dian)(DC-DC從其工作(zuo)原(yuan)理上來(lai)說就是開(kai)關(guan)電(dian)源(yuan)(yuan))。還有,開(kai)關(guan)電(dian)源(yuan)(yuan)中用(yong)到的高頻(pin)變壓器可能繞制起來(lai)比(bi)較麻煩
開(kai)(kai)關(guan)電(dian)(dian)源和線性電(dian)(dian)源在(zai)內(nei)部結(jie)構上是(shi)(shi)完全不一樣的(de)(de)(de),開(kai)(kai)關(guan)電(dian)(dian)源顧名(ming)思義(yi)有開(kai)(kai)關(guan)動(dong)作,它利用變占空比或(huo)變頻的(de)(de)(de)方法實(shi)(shi)現不同的(de)(de)(de)電(dian)(dian)壓,實(shi)(shi)現較為復(fu)雜(za),最大的(de)(de)(de)優(you)點(dian)是(shi)(shi)高(gao)(gao)效率,一般(ban)在(zai)90%以上,缺點(dian)是(shi)(shi)文波(bo)和開(kai)(kai)關(guan)噪聲(sheng)(sheng)較大,適(shi)用于對文波(bo)和噪聲(sheng)(sheng)要(yao)求不高(gao)(gao)的(de)(de)(de)場合(he);而線性電(dian)(dian)源沒有開(kai)(kai)關(guan)動(dong)作,屬(shu)于連續模(mo)擬控制,內(nei)部結(jie)構相(xiang)對簡(jian)單,芯片(pian)面(mian)積也較小,成本(ben)較低(di),優(you)點(dian)是(shi)(shi)成本(ben)低(di),文波(bo)噪聲(sheng)(sheng)小,最大的(de)(de)(de)缺點(dian)是(shi)(shi)效率低(di)。它們各有有缺點(dian)在(zai)應用上互補共存!
一、線性電源的原理:
線(xian)性電(dian)(dian)(dian)(dian)(dian)源(yuan)主要包括工頻(pin)變壓(ya)(ya)(ya)(ya)器(qi)、輸出(chu)整(zheng)流(liu)濾波(bo)(bo)器(qi)、控制電(dian)(dian)(dian)(dian)(dian)路、保護(hu)電(dian)(dian)(dian)(dian)(dian)路等。 線(xian)性電(dian)(dian)(dian)(dian)(dian)源(yuan)是(shi)先將(jiang)交流(liu)電(dian)(dian)(dian)(dian)(dian)經(jing)過(guo)變壓(ya)(ya)(ya)(ya)器(qi)變壓(ya)(ya)(ya)(ya),再經(jing)過(guo)整(zheng)流(liu)電(dian)(dian)(dian)(dian)(dian)路整(zheng)流(liu)濾波(bo)(bo)得到未穩(wen)定的(de)直(zhi)流(liu)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya),要達(da)到高精(jing)度(du)的(de)直(zhi)流(liu)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya),必須(xu)經(jing)過(guo)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)反(fan)饋調整(zheng)輸出(chu)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya),這(zhe)種電(dian)(dian)(dian)(dian)(dian)源(yuan)技術很成熟,可以(yi)達(da)到很高的(de)穩(wen)定度(du),波(bo)(bo)紋(wen)也很小,而且(qie)沒有開關(guan)電(dian)(dian)(dian)(dian)(dian)源(yuan)具有的(de)干擾與噪音。但是(shi)它的(de)缺點是(shi)需(xu)要龐大(da)(da)而笨重的(de)變壓(ya)(ya)(ya)(ya)器(qi),所(suo)需(xu)的(de)濾波(bo)(bo)電(dian)(dian)(dian)(dian)(dian)容的(de)體積和重量(liang)也相當大(da)(da),而且(qie)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)反(fan)饋電(dian)(dian)(dian)(dian)(dian)路是(shi)工作在(zai)線(xian)性狀態,調整(zheng)管(guan)上有一定的(de)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)降,在(zai)輸出(chu)較大(da)(da)工作電(dian)(dian)(dian)(dian)(dian)流(liu)時,致(zhi)使調整(zheng)管(guan)的(de)功耗太大(da)(da),轉換效率低,還(huan)要安裝很大(da)(da)的(de)散(san)熱片。這(zhe)種電(dian)(dian)(dian)(dian)(dian)源(yuan)不適合計算機等設備的(de)需(xu)要,將(jiang)逐步被(bei)開關(guan)電(dian)(dian)(dian)(dian)(dian)源(yuan)所(suo)取代。
二(er)、開關(guan)電源的原理:
開關電(dian)源主要包括輸入電(dian)網濾(lv)波(bo)器、輸入整流濾(lv)波(bo)器、逆變(bian)器、輸出整流濾(lv)波(bo)器、控制電(dian)路、保護電(dian)路。它們(men)的(de)功能是:
1、輸入電網(wang)(wang)濾波器(qi):消除(chu)來自電網(wang)(wang),如電動(dong)機(ji)的啟動(dong)、電器(qi)的開關、雷擊等產(chan)生(sheng)(sheng)的干擾,同時也防止(zhi)開關電源產(chan)生(sheng)(sheng)的高(gao)頻噪(zao)聲向電網(wang)(wang)擴散。
2、輸入整(zheng)流濾波器(qi):將(jiang)電網輸入電壓進行(xing)整(zheng)流濾波,為(wei)變換器(qi)提供直流電壓。
3、逆變器:是(shi)開關電源的關鍵部(bu)分。它把(ba)直(zhi)流電壓變換(huan)成(cheng)高頻交流電壓,并且起到將輸出部(bu)分與輸入電網(wang)隔離(li)的作用。
4、輸(shu)出整(zheng)(zheng)流濾波器(qi):將變換器(qi)輸(shu)出的高頻交流電(dian)壓整(zheng)(zheng)流濾波得到需(xu)要的直流電(dian)壓,同時還防止高頻噪聲對負(fu)載的干擾(rao)。
5、控制電(dian)(dian)路:檢測輸出(chu)直(zhi)流(liu)電(dian)(dian)壓(ya)(ya)(ya),并(bing)將其與基準(zhun)電(dian)(dian)壓(ya)(ya)(ya)比較,進(jin)行放大。調制振(zhen)蕩器的脈沖寬度,從(cong)而控制變換器以保持輸出(chu)電(dian)(dian)壓(ya)(ya)(ya)的穩定(ding)。
6、保(bao)(bao)護電(dian)路:當(dang)開關電(dian)源發生過(guo)電(dian)壓、過(guo)電(dian)流短路時,保(bao)(bao)護電(dian)路使開關電(dian)源停止工作以保(bao)(bao)護負載和電(dian)源本身。
開(kai)(kai)關(guan)電(dian)(dian)(dian)源(yuan)是將(jiang)交(jiao)流(liu)(liu)電(dian)(dian)(dian)先整(zheng)流(liu)(liu)成(cheng)直(zhi)流(liu)(liu)電(dian)(dian)(dian),在(zai)將(jiang)直(zhi)流(liu)(liu)逆變(bian)成(cheng)交(jiao)流(liu)(liu)電(dian)(dian)(dian),在(zai)整(zheng)流(liu)(liu)輸(shu)出成(cheng)所需(xu)要(yao)的(de)直(zhi)流(liu)(liu)電(dian)(dian)(dian)壓(ya)。這(zhe)樣(yang)開(kai)(kai)關(guan)電(dian)(dian)(dian)源(yuan)省去下線(xian)性電(dian)(dian)(dian)源(yuan)中(zhong)(zhong)的(de)變(bian)壓(ya)器,以及電(dian)(dian)(dian)壓(ya)反饋電(dian)(dian)(dian)路(lu)。而開(kai)(kai)關(guan)電(dian)(dian)(dian)源(yuan)中(zhong)(zhong)的(de)逆變(bian)電(dian)(dian)(dian)路(lu)完全是數字調(diao)整(zheng),同樣(yang)能(neng)達(da)到(dao)非常高的(de)調(diao)整(zheng)精度。
開關電源的主要優(you)點:
體(ti)積(ji)小、重(zhong)量(liang)輕(體(ti)積(ji)和重(zhong)量(liang)只有線(xian)性(xing)(xing)(xing)電(dian)(dian)源的(de)20~30%)、效(xiao)率高(一般為60~70%,而線(xian)性(xing)(xing)(xing)電(dian)(dian)源只有30~40%)、自身(shen)抗干擾性(xing)(xing)(xing)強(qiang)、輸出電(dian)(dian)壓范(fan)圍寬、模塊(kuai)化(hua)。
開關電源的主要缺點:
由于逆變電(dian)路中(zhong)會(hui)產生(sheng)高頻(pin)電(dian)壓,對周圍(wei)設備(bei)有一(yi)定的(de)(de)干擾(rao)。需要良(liang)好(hao)的(de)(de)屏蔽及接地
開(kai)關(guan)電(dian)(dian)(dian)源就是用(yong)通(tong)過電(dian)(dian)(dian)路控(kong)制開(kai)關(guan)管(guan)進行(xing)高(gao)速的(de)道通(tong)與(yu)截(jie)止(zhi).將直流(liu)電(dian)(dian)(dian)轉化為(wei)高(gao)頻(pin)率(lv)的(de)交(jiao)流(liu)電(dian)(dian)(dian)提供給變(bian)(bian)壓(ya)器進行(xing)變(bian)(bian)壓(ya),從而產(chan)生所需要(yao)的(de)一(yi)組或多(duo)組電(dian)(dian)(dian)壓(ya)!轉華為(wei)高(gao)頻(pin)交(jiao)流(liu)電(dian)(dian)(dian)的(de)原因是高(gao)頻(pin)交(jiao)流(liu)在變(bian)(bian)壓(ya)器變(bian)(bian)壓(ya)電(dian)(dian)(dian)路中的(de)效率(lv)要(yao)比(bi)50Hz高(gao)很(hen)多(duo).所以開(kai)關(guan)變(bian)(bian)壓(ya)器可以做的(de)很(hen)小(xiao),而且工作時不(bu)(bu)是很(hen)熱!!成(cheng)本很(hen)低.如果不(bu)(bu)將50Hz變(bian)(bian)為(wei)高(gao)頻(pin)那開(kai)關(guan)電(dian)(dian)(dian)源就沒有意義!!開(kai)關(guan)變(bian)(bian)壓(ya)器也(ye)不(bu)(bu)神秘.就是一(yi)個普通(tong)的(de)變(bian)(bian)壓(ya)器!這就是開(kai)關(guan)電(dian)(dian)(dian)源。
開關電(dian)源(yuan),是通(tong)過(guo)電(dian)子技術實現的,主要環節:整流成直流電(dian)——逆變(bian)成所(suo)需(xu)電(dian)壓的交(jiao)流電(dian)(主要來調整電(dian)壓)——再經過(guo)整流成直流電(dian)壓輸出。
開關電源的結(jie)構中由于中間(jian)沒有變(bian)壓(ya)器和散(san)熱片,因而體(ti)積非(fei)(fei)常小。同時,開關電源內部(bu)都是(shi)電子元件,效率(lv)高、發(fa)熱小。雖然,具有電磁(ci)干擾等缺點,但現在的屏蔽(bi)技術(shu)已經(jing)非(fei)(fei)常到位(wei)。
開(kai)關(guan)電源大體(ti)可以(yi)分(fen)為隔(ge)(ge)(ge)離和非隔(ge)(ge)(ge)離兩種,隔(ge)(ge)(ge)離型的(de)必(bi)定(ding)有開(kai)關(guan)變壓器(qi),而非隔(ge)(ge)(ge)離的(de)未必(bi)一定(ding)有。
簡單地(di)說,開(kai)關(guan)電源(yuan)的工作原理是:
1.交流(liu)電源輸入經整流(liu)濾波成直流(liu);
2.通過(guo)高頻PWM(脈(mo)沖寬度調制(zhi))信號控制(zhi)開關管,將那個(ge)直流(liu)加到開關變壓(ya)器初(chu)級上(shang);
3.開關變壓(ya)器(qi)次級感應出高(gao)頻電壓(ya),經整流濾波供給負載;
4.輸出部分通過一定的電路(lu)反饋給控制電路(lu),控制PWM占空比,以達到穩定輸出的目(mu)的.
交流電(dian)(dian)源(yuan)輸入時一般要經過(guo)厄(e)流圈(quan)一類的(de)東西,過(guo)濾(lv)掉(diao)電(dian)(dian)網上(shang)的(de)干擾(rao),同(tong)時也過(guo)濾(lv)掉(diao)電(dian)(dian)源(yuan)對(dui)電(dian)(dian)網的(de)干擾(rao);在(zai)功率相同(tong)時,開(kai)(kai)關頻率越高(gao),開(kai)(kai)關變(bian)壓器的(de)體積(ji)就(jiu)越小,但對(dui)開(kai)(kai)關管的(de)要求就(jiu)越高(gao);開(kai)(kai)關變(bian)壓器的(de)次(ci)級可(ke)以(yi)有多個(ge)繞(rao)(rao)組或一個(ge)繞(rao)(rao)組有多個(ge)抽頭,以(yi)得(de)到需要的(de)輸出;一般還應該(gai)增加一些保護電(dian)(dian)路(lu),比如(ru)空載、短(duan)路(lu)等(deng)保護,否則可(ke)能會燒毀開(kai)(kai)關電(dian)(dian)源(yuan)。
以上說的(de)就是開關(guan)電源的(de)大致工(gong)作原(yuan)理。
其實現在(zai)已經有了集(ji)成(cheng)度(du)非常高的專用芯片,可(ke)以使外圍電(dian)路(lu)非常簡單,甚至(zhi)做到免調試(shi)。
例如TOP系列的開關電源芯片(或稱模塊),只要配合(he)一些阻容(rong)元(yuan)件(jian),和一個(ge)開關變(bian)壓器,就可以做(zuo)成一個(ge)基本的開關電源。
開關電(dian)源&線性電(dian)源
開(kai)(kai)關電(dian)源(yuan)的(de)主要工(gong)作原(yuan)理就是上(shang)(shang)橋(qiao)和下橋(qiao)的(de)Mos管(guan)輪流(liu)導(dao)通,首(shou)先電(dian)流(liu)通過上(shang)(shang)橋(qiao)Mos管(guan)流(liu)入,利用線(xian)(xian)圈(quan)的(de)存儲功能,將電(dian)能集聚在線(xian)(xian)圈(quan)中(zhong),最后關閉上(shang)(shang)橋(qiao)Mos管(guan),打開(kai)(kai)下橋(qiao)的(de)Mos管(guan),線(xian)(xian)圈(quan)和電(dian)容持續給外部(bu)供電(dian)。然后又(you)關閉下橋(qiao)Mos管(guan),再打開(kai)(kai)上(shang)(shang)橋(qiao)讓(rang)電(dian)流(liu)進(jin)入,就這樣(yang)重復進(jin)行,因為(wei)要輪流(liu)開(kai)(kai)關Mos管(guan),所以(yi)稱為(wei)開(kai)(kai)關電(dian)源(yuan)。
而(er)線(xian)性(xing)電(dian)(dian)源(yuan)就不一樣(yang)了,由于沒有(you)(you)開(kai)關介(jie)入,使得上水管一直在放水,如(ru)果有(you)(you)多(duo)的(de)(de),就會漏出(chu)來,這(zhe)就是我們經常(chang)看到的(de)(de)某些線(xian)性(xing)電(dian)(dian)源(yuan)的(de)(de)Mos管發(fa)熱(re)量很大(da),用不完(wan)的(de)(de)電(dian)(dian)能,全部轉換成了熱(re)能。從這(zhe)個角度來看,線(xian)性(xing)電(dian)(dian)源(yuan)的(de)(de)轉換效率就非常(chang)低了,而(er)且熱(re)量高(gao)的(de)(de)時候,元件的(de)(de)壽命(ming)勢(shi)必要下降,影響最終的(de)(de)使用效果 。
開關電源和線性電源的區別主要(yao)是(shi)他(ta)們的工作方式。
線性(xing)電(dian)源功(gong)率(lv)器(qi)件工(gong)作(zuo)在線性(xing)狀態,也(ye)(ye)就(jiu)是(shi)說他(ta)(ta)一用起來功(gong)率(lv)器(qi)件就(jiu)是(shi)一直在工(gong)作(zuo),所以也(ye)(ye)就(jiu)導致他(ta)(ta)的(de)(de)工(gong)作(zuo)效(xiao)率(lv)低,一般(ban)在50%~60%,還得說他(ta)(ta)是(shi)很(hen)好的(de)(de)線性(xing)電(dian)源。線性(xing)電(dian)源的(de)(de)工(gong)作(zuo)方式(shi),使他(ta)(ta)從高壓變低壓必須(xu)有將壓裝置(zhi),一般(ban)的(de)(de)都是(shi)變壓器(qi),也(ye)(ye)有別的(de)(de)像(xiang)KX電(dian)源,再經(jing)過整(zheng)流輸出直流電(dian)壓。這樣一來他(ta)(ta)的(de)(de)體(ti)積(ji)也(ye)(ye)就(jiu)很(hen)大(da)(da),笨重,效(xiao)率(lv)低、發熱量(liang)也(ye)(ye)大(da)(da)。他(ta)(ta)也(ye)(ye)有他(ta)(ta)的(de)(de)優(you)點:紋波小(xiao),調整(zheng)率(lv)好,對外干擾小(xiao)。適合用與(yu)模(mo)擬電(dian)路,各(ge)類放大(da)(da)器(qi)等。
開(kai)關(guan)(guan)(guan)電(dian)源(yuan)。他(ta)的功(gong)率(lv)器件工作在(zai)開(kai)關(guan)(guan)(guan)狀態,(一(yi)開(kai)一(yi)關(guan)(guan)(guan),一(yi)開(kai)一(yi)關(guan)(guan)(guan),頻率(lv)非(fei)常(chang)快(kuai),一(yi)般的平板開(kai)關(guan)(guan)(guan)電(dian)源(yuan)頻率(lv)在(zai)100~200KHz,模(mo)塊電(dian)源(yuan)在(zai)300~500KHZ).這樣(yang)他(ta)的損耗就小(xiao),效(xiao)(xiao)率(lv)也就高,對變壓器也有了要求(qiu),要用高磁導(dao)率(lv)的材料來(lai)做(zuo).有點墨跡(ji)了,他(ta)的變壓器就是(shi)一(yi)個字(zi)小(xiao).效(xiao)(xiao)率(lv)80%~90%吧.據說美國最好的VICOR模(mo)塊高達99%.開(kai)關(guan)(guan)(guan)電(dian)源(yuan)的效(xiao)(xiao)率(lv)高體(ti)積(ji)小(xiao),但(dan)是(shi)和線(xian)性電(dian)源(yuan)比他(ta)的紋波(bo),電(dian)壓電(dian)流(liu)調整率(lv)就有折扣了 。
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