介(jie)於(yu)P+注(zhu)入(ru)區(ou)與(yu)N*漂(piao)移(yi)區(ou)之(zhi)間(jian)的(di)N’層(ceng)稱(chen)為(wei)緩(huan)衝(chong)區(ou)。有(you)無(wu)緩(huan)衝(chong)區(ou)可(ke)以(yi)獲(huo)得(dei)不(bu)同(tong)特(te)性(xing)的(di)IGBT有(you)N+緩(huan)衝(chong)區(ou)的(di)IGBT稱(chen)為(wei)非(fei)對(dui)稱(chen)型(xing)(也(ye)稱(chen)穿(chuan)通(tong)型(xing)) IGBT ,它(ta)具(ju)有(you)正(zheng)向(xiang)壓(ya)降(xiang)小(xiao)關(guan)斷(duan)時(shi)間(jian)短(duan)、關(guan)斷(duan)時(shi)尾(yi)部(bu)電(dian)流(liu)小(xiao)等(deng)優(you)點(dian),但(dan)反(fan)向(xiang)阻(zu)斷(duan)能(neng)力(li)相(xiang)對(dui)較(jiao)弱(ruo)。
無(wu)N*緩(huan)衝(chong)區(ou)的(di)IGBT稱(chen)為(wei)對(dui)稱(chen)型(xing)(也(ye)稱(chen)非(fei)穿(chuan)通(tong)型(xing)) IGBT ,具(ju)有(you)較(jiao)強(jiang)的(di)正(zheng)反(fan)向(xiang)阻(zu)斷(duan)能(neng)力(li),但(dan)其(qi)他(ta)特(te)性(xing)卻(que)不(bu)及(ji)非(fei)對(dui)稱(chen)型(xing)IGBT。在(zai)圖(tu)3-10(a)中(zhong) , C為(wei)集(ji)電(dian)極(ji),E為(wei)發(fa)射(she)極(ji),G為(wei)柵(zha)極(ji)(也(ye)稱(chen)門(men)極(ji))。該(gai)器(qi)件(jian)的(di)電(dian)氣(qi)圖(tu)形(xing)符(fu)號(hao)如(ru)圖(tu)3-10 ( C )所(suo)示(shi),圖(tu)中(zhong)所(suo)示(shi)箭(jian)頭(tou)表(biao)示(shi)IGBT中(zhong)電(dian)流(liu)流(liu)動(dong)的(di)方(fang)向(xiang)( P溝(gou)道(dao)IGBT的(di)箭(jian)頭(tou)與(yu)其(qi)相(xiang)反(fan))。
②工(gong)作(zuo)原(yuan)理(li)簡(jian)單(shan)來(lai)說(shui) , IGBT相(xiang)當(dang)於(yu)一(yi)個(ge)由(you)MOSFET驅(qu)動(dong)的(di)厚(hou)基(ji)區(ou)PNP晶(jing)體(ti)管(guan),它(ta)的(di)簡(jian)化(hua)等(deng)效(xiao)電(dian)路(lu)如(ru)圖(tu)3-10 ( b )所(suo)示(shi),圖(tu)中(zhong)RN為(wei)PNP晶(jing)體(ti)管(guan)基(ji)區(ou)內(nei)的(di)調(diao)製(zhi)電(dian)阻(zu)。從(zong)該(gai)等(deng)效(xiao)電(dian)路(lu)可(ke)以(yi)清(qing)楚(chu)地(de)看(kan)出(chu)，IGBT是(shi)用(yong)晶(jing)體(ti)管(guan)和(hu)功(gong)率(shuai)MOSFET組(zu)成(cheng)的(di)複(fu)合(ge)器(qi)件(jian)。因(yin)為(wei)圖(tu)中(zhong)的(di)晶(jing)體(ti)管(guan)為(wei)PNP型(xing)晶(jing)體(ti)管(guan)，MOSFET為(wei)N溝(gou)道(dao)場(chang)效(xiao)應(ying)晶(jing)體(ti)管(guan),所(suo)以(yi)這(zhe)種(zhong)結(jie)構(gou)的(di)IGBT稱(chen)為(wei)N溝(gou)道(dao)IGBT。類(lei)似(shi)地(de)還(huan)有(you)P溝(gou)道(dao)IGBTIGBT是(shi)一(yi)種(zhong)場(chang)控(kong)器(qi)件(jian),它(ta)的(di)開(kai)通(tong)和(hu)關(guan)斷(duan)由(you)柵(zha)極(ji)和(hu)發(fa)射(she)極(ji)間(jian)電(dian)壓(ya)Ug;決(jue)定(ding)。當(dang)柵(zha)射(she)極(ji)電(dian)壓(ya)UgE為(wei)正(zheng)且(qie)大(dai)於(yu)開(kai)啟(qi)電(dian)壓(ya)UGE (th)時(shi), MOSFET內(nei)形(xing)成(cheng)溝(gou)道(dao)並(bing)為(wei)PNP晶(jing)體(ti)管(guan)提(ti)供(gong)基(ji)極(ji)電(dian)流(liu),進(jin)而(er)使(shi)IGBT導(dao)通(tong)。此(ci)時(shi),從(zong)P*區(ou)注(zhu)入(ru)N的(di)空(kong)穴(xue)(少(shao)數(shuo)載(zai)流(liu)子(zi))對(dui)N~區(ou)進(jin)行(hang)電(dian)導(dao)調(diao)製(zhi),減(jian)小(xiao)N~區(ou)的(di)電(dian)阻(zu)RN ,使(shi)高(gao)耐(nai)壓(ya)的(di)IGBT也(ye)具(ju)有(you)很(hen)低(di)的(di)通(tong)態(tai)壓(ya)降(xiang)。當(dang)柵(zha)射(she)極(ji)間(jian)不(bu)加(jia)信(xin)號(hao)或(huo)加(jia)反(fan)向(xiang)電(dian)壓(ya)時(shi), MOSFET內(nei)的(di)溝(gou)道(dao)消(xiao)失(shi),則(ze)PNP晶(jing)體(ti)管(guan)的(di)基(ji)極(ji)電(dian)流(liu)被(bei)切(qie)斷(duan), IGBT即(ji)關(guan)斷(duan)。由(you)此(ci)可(ke)見(xian), IGBT的(di)驅(qu)動(dong)原(yuan)理(li)與(yu)MOSFET基(ji)本(ben)相(xiang)同(tong)。
(2)基(ji)本(ben)特(te)性(xing)
①靜(jing)態(tai)特(te)性(xing)IGBT的(di)靜(jing)態(tai)特(te)性(xing)包(bao)括(kuo)轉(zhuan)移(yi)特(te)性(xing)和(hu)輸(shu)出(chu)特(te)性(xing)。
a.轉(zhuan)移(yi)特(te)性(xing)。IGBT的(di)轉(zhuan)移(yi)特(te)性(xing)用(yong)來(lai)描(miao)述(shu)IGBT集(ji)電(dian)極(ji)電(dian)流(liu)Ic與(yu)柵(zha)射(she)電(dian)壓(ya)UGE間(jian)的(di)相(xiang)互(hu)關(guan)係(ji),如(ru)圖(tu)3-11 ( a )所(suo)示(shi)。此(ci)特(te)性(xing)與(yu)功(gong)率(shuai)MOSFET的(di)轉(zhuan)移(yi)特(te)性(xing)相(xiang)似(shi)。由(you)圖(tu)3-11 (a)可(ke)知(zhi), Ic與(yu)Uq;基(ji)本(ben)呈(cheng)線(xian)性(xing)關(guan)係(ji)，隻(zhi)有(you)當(dang)UGE在(zai)UGE(th)附(fu)近(jin)時(shi)才(cai)呈(cheng)非(fei)線(xian)性(xing)關(guan)係(ji)。當(dang)柵(zha)射(she)電(dian)壓(ya)Ug;小(xiao)於(yu)UqGE ( th)時(shi), IGBT處(chu)於(yu)關(guan)斷(duan)狀(zhuang)態(tai);當(dang)Ug大(dai)於(yu)UcGE(th)時(shi)，IGBT開(kai)始(shi)導(dao)通(tong)。由(you)此(ci)可(ke)知(zhi), UGE( th)是(shi)IGBT能(neng)實(shi)現(xian)電(dian)導(dao)調(diao)製(zhi)而(er)導(dao)通(tong)的(di)柵(zha)射(she)電(dian)壓(ya)。UGE ( th)隨(sui)溫(wen)度(duo)升(sheng)高(gao)略(lüe)有(you)下(xia)降(xiang),溫(wen)度(duo)每(mei)升(sheng)高(gao)1°C ,其(qi)值(zhi)下(xia)降(xiang)5mV左(zuo)右(you)。在(zai)25°C時(shi), IGBT的(di)開(kai)啟(qi)電(dian)壓(ya)UGGE(th)一(yi)般(pan)為(wei)2 ~ 6V。
b輸(shu)出(chu)特(te)性(xing)。IGBT的(di)輸(shu)出(chu)特(te)性(xing)也(ye)稱(chen)伏(fu)安(an)特(te)性(xing),它(ta)描(miao)述(shu)的(di)是(shi)以(yi)柵(zha)射(she)電(dian)壓(ya)UGE為(wei)控(kong)製(zhi)變(bian)量(liang)時(shi)集(ji)電(dian)極(ji)電(dian)流(liu)Ic與(yu)集(ji)射(she)極(ji)間(jian)電(dian)壓(ya)UcE之(zhi)間(jian)的(di)關(guan)係(ji)。IGBT的(di)輸(shu)出(chu)特(te)性(xing)如(ru)圖(tu)3-11 ( b )所(suo)示(shi)。此(ci)特(te)性(xing)與(yu)GTR的(di)輸(shu)出(chu)特(te)性(xing)相(xiang)似(shi),不(bu)同(tong)的(di)是(shi)控(kong)製(zhi)變(bian)量(liang), IGBT為(wei)柵(zha)射(she)電(dian)壓(ya)UGE ,而(er)晶(jing)體(ti)管(guan)為(wei)基(ji)極(ji)電(dian)流(liu)Ig。IGBT的(di)輸(shu)出(chu)特(te)性(xing)分(fen)正(zheng)向(xiang)阻(zu)斷(duan)區(ou)、有(you)源(yuan)區(ou)和(hu)飽(bao)和(hu)區(ou)。當(dang)UGE <0時(shi), IGBT為(wei)反(fan)向(xiang)阻(zu)斷(duan)工(gong)作(zuo)狀(zhuang)態(tai)。參(shen)照(zhao)圖(tu)3-11(a)可(ke)知(zhi)，此(ci)時(shi)P+N結(jie)(Jj結(jie))處(chu)於(yu)反(fan)偏(pian)狀(zhuang)態(tai),因(yin)而(er)不(bu)管(guan)MOSFET的(di)溝(gou)道(dao)體(ti)區(ou)中(zhong)有(you)沒(mo)有(you)形(xing)成(cheng)溝(gou)道(dao), 均(jun)不(bu)會(kuai)有(you)集(ji)電(dian)極(ji)電(dian)流(liu)出(chu)現(xian)。由(you)此(ci)可(ke)見(xian), IGBT由(you)於(yu)比(bi)MOFET多(duo)了(liao)一(yi)一(yi)個(ge)J結(jie)而(er)獲(huo)得(dei)反(fan)向(xiang)電(dian)壓(ya)阻(zu)斷(duan)能(neng)力(li)1IGBT能(neng)夠(gou)承(cheng)受(shou)的(di)反(fan)向(xiang)阻(zu)斷(duan)電(dian)壓(ya)URn取(qu)決(jue)於(yu)J1結(jie)的(di)雪(xue)崩(beng)擊(ji)穿(chuan)電(dian)壓(ya)。當(dang)UcE> 而(er)UGE< UGE(th )時(shi), IGBT為(wei)正(zheng)向(xiang)阻(zu)斷(duan)工(gong)作(zuo)狀(zhuang)態(tai)。此(ci)時(shi)J結(jie)處(chu)於(yu)反(fan)偏(pian)狀(zhuang)態(tai),且(qie)MOSFET的(di)溝(gou)道(dao)體(ti)區(ou)內(nei)沒(mo)有(you)形(xing)成(cheng)溝(gou)道(dao), IGBT的(di)集(ji)電(dian)極(ji)漏(lou)電(dian)流(liu)IcEs很(hen)小(xiao)。IGBT能(neng)夠(gou)承(cheng)受(shou)的(di)正(zheng)向(xiang)阻(zu)斷(duan)電(dian)壓(ya)UFμ取(qu)決(jue)於(yu)J2的(di)雪(xue)崩(beng)擊(ji)穿(chuan)電(dian)壓(ya)。如(ru)果(guo)UcE> 0而(er)且(qie)UGE< UGE (th)時(shi), MOSFET的(di)溝(gou)通(tong)體(ti)區(ou)內(nei)形(xing)成(cheng)導(dao)電(dian)溝(gou)道(dao)，IGBT進(jin)入(ru)正(zheng)向(xiang)導(dao)通(tong)狀(zhuang)態(tai)。
此(ci)時(shi),由(you)於(yu)J1結(jie)處(chu)於(yu)正(zheng)偏(pian)狀(zhuang)態(tai), P+區(ou)將(qiang)向(xiang)N基(ji)區(ou)注(zhu)入(ru)空(kong)穴(xue)。當(dang)正(zheng)偏(pian)壓(ya)升(sheng)高(gao)時(shi),注(zhu)入(ru)空(kong)穴(xue)的(di)密(mi)度(duo)也(ye)相(xiang)應(ying)增(zeng)大(dai),直(zhi)到(dao)超(chao)過(guo)N基(ji)區(ou)的(di)多(duo)數(shuo)載(zai)流(liu)子(zi)密(mi)度(duo)為(wei)止(zhi)。在(zai)這(zhe)種(zhong)狀(zhuang)態(tai)工(gong)作(zuo)時(shi),隨(sui)著(zhuo)柵(zha)射(she)電(dian)壓(ya)UgE的(di)升(sheng)高(gao),向(xiang)N基(ji)區(ou)提(ti)供(gong)電(dian)子(zi)的(di)導(dao)電(dian)溝(gou)道(dao)加(jia)寬(kuan),集(ji)電(dian)極(ji)電(dian)流(liu)Ic將(qiang)增(zeng)大(dai),在(zai)正(zheng)向(xiang)導(dao)通(tong)的(di)大(dai)部(bu)分(fen)區(ou)域(yu)內(nei), Ic與(yu)UcE呈(cheng)線(xian)性(xing)關(guan)係(ji),而(er)與(yu)UcE無(wu)關(guan),這(zhe)部(bu)分(fen)區(ou)域(yu)稱(chen)為(wei)有(you)源(yuan)區(ou)或(huo)線(xian)性(xing)區(ou)。IGBT的(di)這(zhe)種(zhong)工(gong)作(zuo)狀(zhuang)態(tai)稱(chen)為(wei)有(you)源(yuan)工(gong)作(zuo)狀(zhuang)態(tai)或(huo)線(xian)性(xing)工(gong)作(zuo)狀(zhuang)態(tai)。對(dui)於(yu)工(gong)作(zuo)在(zai)開(kai)關(guan)狀(zhuang)態(tai)的(di)IGBT ,應(ying)盡(jin)量(liang)避(bi)免(wen)_工(gong)作(zuo)在(zai)有(you)源(yuan)區(ou)(線(xian)性(xing)區(ou)) ,否(pi)則(ze)IGBT的(di)功(gong)耗(hao)將(qiang)會(kuai)很(hen)大(dai)。飽(bao)和(hu)區(ou)是(shi)指(zhi)輸(shu)出(chu)特(te)性(xing)比(bi)較(jiao)明(ming)顯(xian)彎(wan)曲(qu)的(di)部(bu)分(fen),此(ci)時(shi)集(ji)電(dian)極(ji)電(dian)流(liu)Ic與(yu)極(ji)射(she)電(dian)壓(ya)Uge不(bu)再(zai)呈(cheng)線(xian)性(xing)關(guan)係(ji)。在(zai)電(dian)力(li)電(dian)子(zi)電(dian)路(lu)中(zhong), IGBT工(gong)作(zuo)在(zai)開(kai)關(guan)狀(zhuang)態(tai),因(yin)而(er)IGBT是(shi)在(zai)正(zheng)向(xiang)阻(zu)斷(duan)區(ou)和(hu)飽(bao)和(hu)區(ou)之(zhi)間(jian)來(lai)回(hui)轉(zhuan)換(huan)。
②動(dong)態(tai)特(te)性(xing)
圖(tu)3-12給(ji)出(chu)了(liao)IGBT開(kai)關(guan)過(guo)程(cheng)的(di)波(bo)形(xing)圖(tu)。IGBT的(di)開(kai)通(tong)過(guo)程(cheng)與(yu)MOSFET的(di)開(kai)通(tong)過(guo)程(cheng)很(hen)相(xiang)似(shi)。這(zhe)是(shi)因(yin)為(wei)IGBT在(zai)開(kai)通(tong)過(guo)程(cheng)中(zhong)大(dai)部(bu)分(fen)時(shi)間(jian)是(shi)作(zuo)為(wei)MOSFET運(yun)行(hang)的(di)。開(kai)通(tong)時(shi)間(jian)ton定(ding)義(yi)為(wei)從(zong)驅(qu)動(dong)電(dian)壓(ya)UcE的(di)脈(mo)衝(chong)前(qian)沿(yan)上(shang)升(sheng)到(dao)10% UGEM (幅(fu)值(zhi))處(chu)起(qi),至(zhi)集(ji)電(dian)極(ji)電(dian)流(liu)Ic上(shang)升(sheng)到(dao)90%Icm處(chu)止(zhi)所(suo)需(xu)要(yao)的(di)時(shi)間(jian)。開(kai)通(tong)時(shi)間(jian)o又(you)可(ke)分(fen)為(wei)開(kai)通(tong)延(yan)遲(chi)時(shi)間(jian)t(on )和(hu)電(dian)流(liu)上(shang)升(sheng)時(shi)間(jian)t,兩(liang)部(bu)分(fen)，td(on )定(ding)義(yi)為(wei)從(zong)10% UGE到(dao)出(chu)現(xian)10% Icr所(suo)需(xu)要(yao)的(di)時(shi)間(jian)，t,定(ding)義(yi)為(wei)集(ji)電(dian)極(ji)電(dian)流(liu)Ic從(zong)10%Icm上(shang)升(sheng)至(zhi)90%IcM所(suo)需(xu)要(yao)的(di)時(shi)間(jian)。集(ji)射(she)電(dian)壓(ya)UcE的(di)下(xia)降(xiang)過(guo)程(cheng)分(fen)成(cheng)tv1和(hu)trn2兩(liang)段(duan), trn段(duan)曲(qu)線(xian)為(wei)IGBT中(zhong)MOSFET單(shan)獨(du)工(gong)作(zuo)的(di)電(dian)壓(ya)下(xia)降(xiang)過(guo)程(cheng)，t+v2段(duan)曲(qu)線(xian)為(wei)MOSFET和(hu)PNP晶(jing)體(ti)管(guan)同(tong)時(shi)工(gong)作(zuo)的(di)電(dian)壓(ya)下(xia)降(xiang)過(guo)程(cheng)。trz段(duan)電(dian)壓(ya) 下(xia)降(xiang)變(bian)緩(huan)的(di)原(yuan)因(yin)有(you)兩(liang)個(ge):其(qi)一(yi)是(shi)UcE電(dian)壓(ya)下(xia)降(xiang)時(shi), IGBT中(zhong)MOSFET的(di)柵(zha)漏(lou)電(dian)容(rong)增(zeng)加(jia),致(zhi)使(shi)電(dian)壓(ya)下(xia)降(xiang)變(bian)緩(huan),這(zhe)與(yu)MOSFET相(xiang)似(shi);其(qi)二(er)是(shi)IGBT的(di)PNP晶(jing)體(ti)管(guan)由(you)放(fang)大(dai)狀(zhuang)態(tai)轉(zhuan)換(huan)到(dao)飽(bao)和(hu)狀(zhuang)態(tai)要(yao)有(you)一(yi)個(ge)過(guo)程(cheng)，下(xia)降(xiang)時(shi)間(jian)變(bian)長(zhang),這(zhe)也(ye)會(kuai)造(zao)成(cheng)電(dian)壓(ya)下(xia)降(xiang)變(bian)緩(huan)。由(you)此(ci)可(ke)知(zhi)IGBT隻(zhi)有(you)在(zai)t2結(jie)束(shu)時(shi)才(cai)完(wan)全(quan)進(jin)入(ru)飽(bao)和(hu)狀(zhuang)態(tai)。
