一、單向晶閘管和雙向晶閘管的區別是什么
晶閘管是一種常用的半導體器件,可以控制電流大小,它的種類眾多,強電電路采用的晶閘管主要(yao)有(you)單(dan)向晶(jing)閘(zha)管和雙向晶(jing)閘(zha)管兩種(zhong),它們(men)之間(jian)的(de)區別主要(yao)有(you):
1、電路符號區別
單(dan)向(xiang)晶閘(zha)(zha)(zha)管縮寫(xie)為(wei)(wei)SCR,雙向(xiang)晶閘(zha)(zha)(zha)管英文縮寫(xie)TRIAC。單(dan)向(xiang)晶閘(zha)(zha)(zha)管的(de)引(yin)腳(jiao)符(fu)(fu)號是K、G、A,其中G極為(wei)(wei)門(men)極,也是控制極,A極為(wei)(wei)陽極,K極為(wei)(wei)陰極。而(er)雙向(xiang)晶閘(zha)(zha)(zha)管的(de)引(yin)腳(jiao)符(fu)(fu)號是T1、T2、G,其中G為(wei)(wei)門(men)極,另外兩個端子因為(wei)(wei)可以(yi)雙向(xiang)導通,所以(yi)不區分陰極和陽極,都是主端子,用T1、T2表(biao)示。
2、工作狀態區別
單向(xiang)晶(jing)閘管若是(shi)用于(yu)直(zhi)流(liu)(liu)電(dian)(dian)(dian)(dian)路(lu)(lu),一旦(dan)觸發信(xin)號開通(tong),并(bing)保(bao)(bao)持(chi)一定幅度的(de)流(liu)(liu)通(tong)電(dian)(dian)(dian)(dian)流(liu)(liu)的(de)話(hua),晶(jing)閘管會一直(zhi)保(bao)(bao)持(chi)開通(tong)狀(zhuang)態。除非將(jiang)電(dian)(dian)(dian)(dian)源開斷一次,才能使(shi)其(qi)關斷。若用于(yu)交流(liu)(liu)電(dian)(dian)(dian)(dian)路(lu)(lu),則在其(qi)承(cheng)受(shou)正向(xiang)電(dian)(dian)(dian)(dian)壓期間(jian)(jian),若接受(shou)一個觸發信(xin)號,則一直(zhi)保(bao)(bao)持(chi)導通(tong),直(zhi)到(dao)電(dian)(dian)(dian)(dian)壓過零(ling)點到(dao)來,因無流(liu)(liu)通(tong)電(dian)(dian)(dian)(dian)流(liu)(liu)而自行(xing)關斷。在承(cheng)受(shou)反(fan)向(xiang)電(dian)(dian)(dian)(dian)壓期間(jian)(jian),即使(shi)送入觸發信(xin)號,晶(jing)閘管也(ye)因A、K間(jian)(jian)電(dian)(dian)(dian)(dian)壓反(fan)向(xiang),而保(bao)(bao)持(chi)于(yu)截(jie)止狀(zhuang)態。
雙(shuang)向(xiang)(xiang)(xiang)晶(jing)(jing)(jing)閘管(guan)第(di)一陽極(ji)T1與第(di)二陽極(ji)T2間,無論所加(jia)電壓(ya)極(ji)性是正向(xiang)(xiang)(xiang)還是反向(xiang)(xiang)(xiang),只(zhi)要(yao)控制極(ji)G和第(di)一陽極(ji)T1間加(jia)有(you)正負極(ji)性不同的(de)觸發電壓(ya),就可觸發導通(tong)(tong)呈低阻狀態。此時(shi)T1、T2間壓(ya)降也(ye)約1V。雙(shuang)向(xiang)(xiang)(xiang)晶(jing)(jing)(jing)閘管(guan)一旦(dan)導通(tong)(tong),即使失去觸發電壓(ya),也(ye)能(neng)繼(ji)續保持導通(tong)(tong)狀態。只(zhi)有(you)當第(di)一陽極(ji)T1、第(di)二陽極(ji)T2電流減小,小于維持電流或T1、T2間當電壓(ya)極(ji)性改變且沒有(you)觸發電壓(ya)時(shi),雙(shuang)向(xiang)(xiang)(xiang)晶(jing)(jing)(jing)閘管(guan)才截斷,此時(shi)只(zhi)有(you)重新加(jia)觸發電壓(ya)方(fang)可導通(tong)(tong)。
3、應用區別
單(dan)向晶閘管因為只有陽極電壓(ya)大于(yu)陰極時,在門(men)極加控制電壓(ya)才會導(dao)通,反(fan)之(zhi)截止(zhi),這(zhe)和二極管的(de)(de)單(dan)向導(dao)電性一(yi)(yi)樣,所以(yi)廣(guang)泛應用(yong)于(yu)可控整流。需要說明的(de)(de)是,一(yi)(yi)旦導(dao)通之(zhi)后,門(men)極信號就無法使其(qi)關斷,只能靠去除負載或降低其(qi)兩端電壓(ya)使其(qi)關斷。
而雙(shuang)向(xiang)晶(jing)閘(zha)管在施加(jia)正向(xiang)或反向(xiang)電壓(ya)(ya)時受到脈沖觸發都會導通(tong)(tong),導通(tong)(tong)具(ju)備(bei)開(kai)關功能(neng),導通(tong)(tong)角可控(kong)具(ju)備(bei)調(diao)壓(ya)(ya)功能(neng),所以雙(shuang)向(xiang)晶(jing)閘(zha)管在交流電路中能(neng)完成(cheng)開(kai)關和調(diao)壓(ya)(ya)雙(shuang)重功能(neng)。
二、晶閘管單向和雙向選哪個
單向晶(jing)閘管(guan)(guan)和雙向晶(jing)閘管(guan)(guan)對比起來,各有其特點,選擇哪個要(yao)看電(dian)路需要(yao):
1、單向(xiang)晶閘管的特點(dian)是電(dian)(dian)流(liu)(liu)只(zhi)能(neng)從(cong)陽(yang)極A流(liu)(liu)向(xiang)陰極k,主(zhu)要應用于直流(liu)(liu)電(dian)(dian)源或魚(yu)流(liu)(liu)脈動電(dian)(dian)壓(ya)(ya)的控制、交(jiao)流(liu)(liu)電(dian)(dian)源整流(liu)(liu)、直流(liu)(liu)電(dian)(dian)源逆(ni)變等場合,如交(jiao)直流(liu)(liu)電(dian)(dian)壓(ya)(ya)控制、可控整流(liu)(liu)、交(jiao)流(liu)(liu)調壓(ya)(ya)、逆(ni)變電(dian)(dian)源、開(kai)關電(dian)(dian)源保護電(dian)(dian)路等。
2、雙向晶閘管是(shi)(shi)在單向晶(jing)(jing)閘管的基礎之上開發出來的,是(shi)(shi)一種交(jiao)(jiao)流(liu)型功率(lv)控(kong)制器(qi)件。雙向晶(jing)(jing)閘管不僅(jin)能夠(gou)取(qu)代兩個反向并聯的單向晶(jing)(jing)閘管,而且只需要(yao)一個觸(chu)發電路,使(shi)用更方便。雙向晶(jing)(jing)閘管的特點是(shi)(shi)可以通(tong)過交(jiao)(jiao)流(liu)電流(liu),主要(yao)應用于交(jiao)(jiao)流(liu)電源的控(kong)制、交(jiao)(jiao)流(liu)電壓(ya)的調整等(deng)場合,如(ru)交(jiao)(jiao)流(liu)開關、交(jiao)(jiao)流(liu)調壓(ya)、交(jiao)(jiao)流(liu)電動機線性(xing)調速、燈具線性(xing)調光及固態繼電器(qi)、固態接觸(chu)器(qi)等(deng)電路。