ANAPF有源電力濾波器

1、ANAPF產品介紹

ANAPF 模塊(kuai)工作原理

ANAPF 系(xi)(xi)(xi)列有(you)源電(dian)(dian)(dian)(dian)力濾波(bo)器并聯在含諧(xie)波(bo)負載的(de)低壓配電(dian)(dian)(dian)(dian)系(xi)(xi)(xi)統中(zhong)，能夠(gou)對動態變化的(de)諧(xie)波(bo)電(dian)(dian)(dian)(dian)流(liu)進行快(kuai)速(su)(su)實 時的(de)跟蹤和補償。其(qi)原(yuan)理為：ANAPF 系(xi)(xi)(xi)列有(you)源電(dian)(dian)(dian)(dian)力濾波(bo)器通過(guo) CT 采集系(xi)(xi)(xi)統諧(xie)波(bo)電(dian)(dian)(dian)(dian)流(liu)，經控制器快(kuai)速(su)(su)計(ji)算并提取 各次諧(xie)波(bo)電(dian)(dian)(dian)(dian)流(liu)的(de)含量(liang)，產生諧(xie)波(bo)電(dian)(dian)(dian)(dian)流(liu)指令(ling)，通過(guo)功率(lv)執行器件產生與諧(xie)波(bo)電(dian)(dian)(dian)(dian)流(liu)幅值相等方向相反(fan)的(de)補償電(dian)(dian)(dian)(dian)流(liu)，并 注(zhu)入(ru)電(dian)(dian)(dian)(dian)力系(xi)(xi)(xi)統中(zhong)，從而抵消(xiao)非線性負載所產生的(de)諧(xie)波(bo)電(dian)(dian)(dian)(dian)流(liu)。

ANAPF 整機工作(zuo)原理

     有源(yuan)電力(li)濾波器是一(yi)種用(yong)于諧(xie)波治(zhi)理、補償(chang)無功以及不(bu)平衡調節(jie)(jie)的新型電力(li)電子裝置；智(zhi)能控制系統主動(dong)根據系 統的線(xian)性動(dong)態需求，自動(dong)調節(jie)(jie)模塊(kuai)的輸出；ANAPF整機主要是由ANAPF模塊(kuai)組成；能完成更大容(rong)量的諧(xie)波電流的補 償(chang)，整機通(tong)過一(yi)個7寸觸(chu)摸屏實(shi)現人(ren)機交互(hu)。觸(chu)摸屏通(tong)過RS485與ANAPF模塊(kuai)進行(xing)通(tong)信。

產品特點

     1) 補償方式(shi)靈活(huo)：既可(ke)補諧波，又(you)可(ke)兼補無功，可(ke)對(dui) 2-51 次諧波進行(xing)全補償或(huo)特定次諧波進行(xing)補償；

     2) 可治理三相不平衡；

     3) 線(xian)性(xing)補(bu)償，響應時間(jian)≤5ms；

     4) 具有(you)人(ren)性化的人(ren)機交(jiao)互界面(mian)，可(ke)通過該(gai)界面(mian)看到系(xi)統和本體的實(shi)時(shi)電能(neng)質(zhi)量信息(xi)，操作簡單，可(ke)以(yi)遠控，也(ye) 可(ke)以(yi)本控；

     5) 采(cai)用(yong)進口(kou) IGBT，功率密度大，可靠性高(gao)；

     6) 采用(yong) DSP 高速檢(jian)測和(he)運算(suan)的(de)數字控制(zhi)系(xi)統；

     7) 監(jian)控以及顯示具(ju)備遠程通(tong)訊接口，可以通(tong)過 PC 機實時(shi)監(jian)控；

     8) 標準模塊化(hua)設(she)計(ji)，縮短交付(fu)周期，同時提高了使用的可靠性(xing)和可維護(hu)性(xing)。

2、外觀尺寸

3、技術參數

4、接線示意

5、諧波電流的估算

絕緣柵場效應晶體管(IGBT)作為一種復合型器件,集成了mosFET的電壓驅動和高開關頻率及功率管低損耗、大功率的特點,在電機控制、開關電源、變流裝置及許多要求快速、低損耗的領域中有著廣泛的應用。本文對應用于有源電力濾波器的(de)(de)IGBT的(de)(de)特性及其專有EXB84l型驅動器的(de)(de)設計進行討論,并提出一(yi)種具有完(wan)善保護(hu)功能的(de)(de)驅動電路。

　　有源電力濾波器設計中(zhong)應(ying)用4個IGBT作(zuo)為開關,并用4個EXB84l組(zu)成驅(qu)動電(dian)(dian)(dian)路(lu),其原理如圖l所示。在實驗中(zhong),根(gen)據補償(chang)電(dian)(dian)(dian)流(liu)與指令電(dian)(dian)(dian)流(liu)的關系,用數字信號處理器(qi)(DSP)控(kong)制(zhi)(zhi)PWM引腳的高低電(dian)(dian)(dian)平,并由驅(qu)動電(dian)(dian)(dian)路(lu)控(kong)制(zhi)(zhi)IGBT的通斷。驅(qu)動電(dian)(dian)(dian)路(lu)同(tong)時對過流(liu)故障(zhang)進行監(jian)測,由DSP采(cai)取控(kong)制(zhi)(zhi)信號、停(ting)機等(deng)處理。

圖1 有源電力濾波器的IGBT驅動電路原理

1 驅動(dong)電路的設計(ji)

1.1 驅動電路電源(yuan)

　　驅(qu)動電(dian)路需要4路相互隔離(li)的直流電(dian)源為4路IGBT驅(qu)動電(dian)路供電(dian),用(yong)(yong)220V/22V變壓器(qi)(qi)對4路交流電(dian)源分別整流,用(yong)(yong)電(dian)容器(qi)(qi)和(he)78L24型電(dian)壓調(diao)整器(qi)(qi)穩(wen)壓后輸出4路24V直流電(dian)壓,如圖2所示(shi)。

圖2 IGBT驅動(dong)電路(lu)的電源(yuan)設計

1.2 柵極電壓

　　IGBT通(tong)(tong)(tong)(tong)常(chang)采用(yong)柵(zha)極(ji)(ji)電(dian)(dian)壓(ya)(ya)驅(qu)(qu)(qu)動(dong),它(ta)對(dui)柵(zha)極(ji)(ji)驅(qu)(qu)(qu)動(dong)電(dian)(dian)路(lu)有著特殊的要求。柵(zha)極(ji)(ji)驅(qu)(qu)(qu)動(dong)電(dian)(dian)壓(ya)(ya)脈沖的上(shang)升率(lv)和(he)下(xia)(xia)降率(lv)要足夠(gou)大,導(dao)(dao)通(tong)(tong)(tong)(tong)時(shi),前沿(yan)很陡(dou)(dou)的柵(zha)極(ji)(ji)電(dian)(dian)壓(ya)(ya)UGE可(ke)以(yi)使(shi)IGBT快(kuai)速(su)導(dao)(dao)通(tong)(tong)(tong)(tong),并減(jian)小導(dao)(dao)通(tong)(tong)(tong)(tong)損(sun)(sun)耗(hao)(hao),關(guan)斷(duan)(duan)(duan)時(shi),其柵(zha)極(ji)(ji)驅(qu)(qu)(qu)動(dong)電(dian)(dian)路(lu)要給IGBT提供(gong)一(yi)個下(xia)(xia)降很陡(dou)(dou)的關(guan)斷(duan)(duan)(duan)電(dian)(dian)壓(ya)(ya),并在(zai)柵(zha)極(ji)(ji)和(he)發射(she)極(ji)(ji)之間(jian)施(shi)加一(yi)個適當的反向負偏(pian)壓(ya)(ya),以(yi)便使(shi)IGBT快(kuai)速(su)關(guan)斷(duan)(duan)(duan),并減(jian)小關(guan)斷(duan)(duan)(duan)損(sun)(sun)耗(hao)(hao)。IGBT導(dao)(dao)通(tong)(tong)(tong)(tong)后,柵(zha)極(ji)(ji)的驅(qu)(qu)(qu)動(dong)電(dian)(dian)壓(ya)(ya)和(he)電(dian)(dian)流要有足夠(gou)的寬度,以(yi)保證IGBT在(zai)瞬時(shi)過載時(shi)未(wei)退(tui)出(chu)飽(bao)(bao)和(he)區受(shou)到損(sun)(sun)壞。柵(zha)極(ji)(ji)驅(qu)(qu)(qu)動(dong)電(dian)(dian)壓(ya)(ya)值(zhi)為(wei)15 V±1.5 V,這個電(dian)(dian)壓(ya)(ya)值(zhi)使(shi)IGBT*飽(bao)(bao)和(he)導(dao)(dao)通(tong)(tong)(tong)(tong),并使(shi)通(tong)(tong)(tong)(tong)態(tai)損(sun)(sun)耗(hao)(hao)減(jian)至小。施(shi)加關(guan)斷(duan)(duan)(duan)負偏(pian)壓(ya)(ya)可(ke)以(yi)抑制C-E間(jian)出(chu)現du/dt時(shi)IGBT的誤導(dao)(dao)通(tong)(tong)(tong)(tong),也可(ke)以(yi)減(jian)少關(guan)斷(duan)(duan)(duan)損(sun)(sun)耗(hao)(hao)。

1.3 門極電阻R1

　　門(men)(men)極電(dian)(dian)阻R1的選取(qu)對通(tong)態電(dian)(dian)壓(ya)、開關時間、開關損耗及承(cheng)受短路的能力都有不(bu)同(tong)程度的影(ying)響。當門(men)(men)極電(dian)(dian)阻增(zeng)(zeng)大(da)時,IGBT的開通(tong)和(he)(he)關斷時間增(zeng)(zeng)加,從而(er)(er)使導通(tong)和(he)(he)關斷損耗增(zeng)(zeng)加。當門(men)(men)極電(dian)(dian)阻減(jian)小時,則會導致di/dt增(zeng)(zeng)加,從而(er)(er)引(yin)起IGBT的誤導通(tong)。所以(yi)應根據IGBT的電(dian)(dian)流容量和(he)(he)電(dian)(dian)壓(ya)額定值以(yi)及開關頻率的不(bu)同(tong)選擇(ze)R1的阻值。

　　Rl的值可以用(yong)下式計算：

　　IC為IGBT的(de)(de)集(ji)電(dian)(dian)(dian)極(ji)電(dian)(dian)(dian)流。如圖3所示,一(yi)般R1取十(shi)幾歐(ou)姆到幾十(shi)歐(ou)姆,R2為30 Ω。由(you)于IGBT是壓控器(qi)件(jian),當集(ji)-射(she)極(ji)間(jian)加(jia)高壓時,很(hen)容易受外界干擾,而(er)使(shi)柵(zha)-射(she)極(ji)間(jian)電(dian)(dian)(dian)壓超過一(yi)定(ding)值,引(yin)(yin)起器(qi)件(jian)誤導(dao)通(tong),為了防止這(zhe)種現象(xiang)的(de)(de)發生,在(zai)(zai)柵(zha)-射(she)極(ji)間(jian)并聯一(yi)電(dian)(dian)(dian)阻(zu)器(qi)R6可(ke)起到一(yi)定(ding)作(zuo)用(yong)。一(yi)般R6阻(zu)值是R2阻(zu)值的(de)(de)l 000~5 000倍,而(er)且應將(jiang)它并聯在(zai)(zai)柵(zha)-射(she)極(ji)近處。電(dian)(dian)(dian)路中的(de)(de)電(dian)(dian)(dian)容器(qi)Cl和C2用(yong)來抑制因電(dian)(dian)(dian)源(yuan)接線阻(zu)抗(kang)引(yin)(yin)起的(de)(de)供電(dian)(dian)(dian)電(dian)(dian)(dian)壓變化(hua),而(er)不是用(yong)于電(dian)(dian)(dian)源(yuan)濾波。

1.4 EXB841驅(qu)動環節(jie)

　　筆者在實驗中采用的是EXB841型IGBT驅動模塊(kuai),其高運行(xing)頻率為(wei)(wei)40 kHz,輸入信號經內部光耦隔離,光隔驅動電流為(wei)(wei)10 mA,大延時(shi)約為(wei)(wei)1 μs。工(gong)作溫度范圍(wei)為(wei)(wei)-10℃~+85℃,供電電壓為(wei)(wei)+20 V～+25 V。筆者對EXB841功能進(jin)行(xing)了擴展,圖3為(wei)(wei)驅動環節(jie)電路(lu)。

圖3 有源電力濾波器的IGBT驅動電路圖

　　EXB841的(de)6引(yin)腳連接的(de)二極管可(ke)檢測IGBT的(de)飽和壓(ya)降,用來完(wan)成過流(liu)保(bao)護(hu)(hu)功能,4引(yin)腳的(de)過流(liu)保(bao)護(hu)(hu)信(xin)(xin)號(hao)延時10μs輸(shu)出。當IGBT有過流(liu)時,若UCE大于(yu)7.5V,內部(bu)過流(liu)保(bao)護(hu)(hu)電(dian)路(lu)開始動(dong)作,軟(ruan)關斷IG-BT。通(tong)(tong)常在IGBT通(tong)(tong)過額(e)定電(dian)流(liu)時UCE為3.5 V,當UCE=7.5 V時,IGBT有過流(liu),其值約為額(e)定電(dian)流(liu)的(de)3~5倍,但(dan)是由于(yu)沒有達(da)到(dao)保(bao)護(hu)(hu)的(de)閾值,保(bao)護(hu)(hu)電(dian)路(lu)不起作用。如果(guo)長時間(jian)工作在這種狀態,則(ze)會導(dao)致IGBT損(sun)壞。為了可(ke)靠地保(bao)護(hu)(hu)IGBT,應(ying)(ying)該降低過流(liu)保(bao)護(hu)(hu)閾值,可(ke)以(yi)在D1與(yu)IGBT的(de)集電(dian)極間(jian)反串一(yi)個穩壓(ya)管,或多串幾個與(yu)D1同規格(ge)的(de)快速恢復二極管。如圖3通(tong)(tong)過反串一(yi)個IN4728型(xing)3.3 V穩壓(ya)管使保(bao)護(hu)(hu)閾值降為4.2V。當檢測到(dao)IGBT過流(liu)后,5引(yin)腳變為低電(dian)平(ping),TPL521型(xing)光耦輸(shu)出低電(dian)平(ping),通(tong)(tong)過與(yu)門(men)控制信(xin)(xin)號(hao)輸(shu)入(ru),同時使4輸(shu)入(ru)與(yu)非門(men)輸(shu)出低電(dian)平(ping),觸發功率驅動(dong)保(bao)護(hu)(hu)中斷,完(wan)成相應(ying)(ying)的(de)保(bao)護(hu)(hu)處(chu)理。

1.5 控制部分與驅動部分的隔離

　　控(kong)制(zhi)電(dian)(dian)(dian)路(lu)為弱電(dian)(dian)(dian)部(bu)分(fen)(fen),極易(yi)受到干擾(rao);驅(qu)動(dong)電(dian)(dian)(dian)路(lu)直接(jie)(jie)與外(wai)電(dian)(dian)(dian)路(lu)連(lian)接(jie)(jie),是一個較強(qiang)的(de)干擾(rao)源;為了實現整個設備(bei)的(de)電(dian)(dian)(dian)磁兼(jian)容,控(kong)制(zhi)電(dian)(dian)(dian)路(lu)部(bu)分(fen)(fen)必(bi)須與驅(qu)動(dong)部(bu)分(fen)(fen)隔離。為了避免公共電(dian)(dian)(dian)源對控(kong)制(zhi)電(dian)(dian)(dian)路(lu)產生干擾(rao),應(ying)對控(kong)制(zhi)電(dian)(dian)(dian)路(lu)及驅(qu)動(dong)電(dian)(dian)(dian)路(lu)分(fen)(fen)別(bie)供電(dian)(dian)(dian),EXB84l的(de)電(dian)(dian)(dian)源電(dian)(dian)(dian)壓(ya)為+20 V,一般控(kong)制(zhi)電(dian)(dian)(dian)路(lu)的(de)供電(dian)(dian)(dian)電(dian)(dian)(dian)壓(ya)為5 V,因此,可以利用圖(tu)4所(suo)示(shi)的(de)DC-DC微(wei)功率模(mo)塊進行電(dian)(dian)(dian)源隔離,采用A2405D型微(wei)功率模(mo)塊實現電(dian)(dian)(dian)源的(de)隔離。

2 IGBT及驅動電路(lu)的保護

2.1 IGBT的(de)過電壓保護(hu)

　　IGBT集-射極之間(jian)(jian)的(de)瞬時(shi)過(guo)壓(ya)會對IGBT造成(cheng)損(sun)壞(huai),筆(bi)者采用(yong)(yong)箝位(wei)式(shi)吸(xi)收(shou)電(dian)(dian)(dian)(dian)路(lu)對瞬時(shi)過(guo)電(dian)(dian)(dian)(dian)壓(ya)進行抑制(zhi)。當(dang)IGBT導(dao)通時(shi),由于二(er)極管的(de)作用(yong)(yong),電(dian)(dian)(dian)(dian)容器的(de)電(dian)(dian)(dian)(dian)荷不(bu)會被(bei)放掉(diao),電(dian)(dian)(dian)(dian)容器電(dian)(dian)(dian)(dian)壓(ya)仍為電(dian)(dian)(dian)(dian)源電(dian)(dian)(dian)(dian)壓(ya)。IGBT關(guan)斷(duan)時(shi),負載電(dian)(dian)(dian)(dian)流(liu)(liu)仍流(liu)(liu)過(guo)IGBT,直到IGBT集-射極之間(jian)(jian)電(dian)(dian)(dian)(dian)壓(ya)達到電(dian)(dian)(dian)(dian)源電(dian)(dian)(dian)(dian)壓(ya),續流(liu)(liu)二(er)極管導(dao)通。應用(yong)(yong)該電(dian)(dian)(dian)(dian)路(lu),可以使雜散電(dian)(dian)(dian)(dian)感中的(de)能量通過(guo)二(er)極管轉儲到吸(xi)收(shou)電(dian)(dian)(dian)(dian)容器中,而IGBT的(de)集電(dian)(dian)(dian)(dian)極電(dian)(dian)(dian)(dian)位(wei)被(bei)箝位(wei)在電(dian)(dian)(dian)(dian)容電(dian)(dian)(dian)(dian)壓(ya)上,這樣就(jiu)可以抑制(zhi)IGBT集電(dian)(dian)(dian)(dian)極的(de)尖峰電(dian)(dian)(dian)(dian)壓(ya)。吸(xi)收(shou)電(dian)(dian)(dian)(dian)容器的(de)容值可以按(an)公式(shi)(2)選取：

　　式中,L是引線電(dian)感;i是IGBT關(guan)斷時(shi)的電(dian)流;△U是吸收(shou)電(dian)容器上的電(dian)壓過沖(chong)。

　　當吸(xi)(xi)(xi)收(shou)回路中的(de)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)器(qi)(qi)(qi)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)高(gao)于直(zhi)流側(ce)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)器(qi)(qi)(qi)上(shang)的(de)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)時(shi),通過電(dian)(dian)(dian)(dian)(dian)(dian)阻器(qi)(qi)(qi)向直(zhi)流側(ce)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)器(qi)(qi)(qi)回送(song)能(neng)(neng)量,一直(zhi)到(dao)與直(zhi)流側(ce)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)器(qi)(qi)(qi)的(de)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)相等(deng)。當IGBT關斷時(shi),線路電(dian)(dian)(dian)(dian)(dian)(dian)感(gan)在集電(dian)(dian)(dian)(dian)(dian)(dian)極和發射極二端產生很高(gao)的(de)尖(jian)(jian)峰(feng)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya),加上(shang)箝位式吸(xi)(xi)(xi)收(shou)電(dian)(dian)(dian)(dian)(dian)(dian)路以(yi)后(hou),UCE被(bei)(bei)箝位在電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)器(qi)(qi)(qi)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)上(shang),當UCE高(gao)于電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)器(qi)(qi)(qi)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)時(shi),線路電(dian)(dian)(dian)(dian)(dian)(dian)感(gan)的(de)能(neng)(neng)量被(bei)(bei)轉移到(dao)吸(xi)(xi)(xi)收(shou)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)器(qi)(qi)(qi)上(shang),當尖(jian)(jian)峰(feng)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)過去以(yi)后(hou),吸(xi)(xi)(xi)收(shou)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)高(gao)于主(zhu)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)的(de)那部分電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)會由(you)于能(neng)(neng)量回進而達(da)到(dao)與主(zhu)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)相等(deng)。這樣就抑制了集-射極間的(de)尖(jian)(jian)峰(feng)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)。吸(xi)(xi)(xi)收(shou)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)越大(da),吸(xi)(xi)(xi)收(shou)效果(guo)越好。由(you)于吸(xi)(xi)(xi)收(shou)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong)器(qi)(qi)(qi)上(shang)過沖的(de)能(neng)(neng)量大(da)部分被(bei)(bei)送(song)回到(dao)直(zhi)流側(ce)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)(rong)(rong),所以(yi)減小了電(dian)(dian)(dian)(dian)(dian)(dian)阻器(qi)(qi)(qi)的(de)功耗(hao)。

2.2 消除IGBT集-柵(zha)極之間(jian)的du/dt

　　圖(tu)5所示為(wei)EXB841與IGBT柵(zha)-射(she)極(ji)(ji)之(zhi)(zhi)(zhi)間(jian)(jian)的(de)(de)(de)連接電(dian)路原(yuan)理圖(tu)。當驅動電(dian)路中的(de)(de)(de)V4導通(tong)(tong)時(shi)(shi),IGBT處(chu)于正常(chang)導通(tong)(tong)狀(zhuang)(zhuang)態(tai),當V5導通(tong)(tong)時(shi)(shi),IGBT柵(zha)-射(she)極(ji)(ji)之(zhi)(zhi)(zhi)間(jian)(jian)通(tong)(tong)過(guo)(guo)穩壓(ya)(ya)管(guan)VZ2提供一(yi)個-5V電(dian)壓(ya)(ya)加在其兩端,使IGBT關斷,此時(shi)(shi)V5處(chu)于臨界導通(tong)(tong)狀(zhuang)(zhuang)態(tai),穩壓(ya)(ya)管(guan)VZ2處(chu)于反向偏置狀(zhuang)(zhuang)態(tai)。但(dan)由于集-柵(zha)極(ji)(ji)之(zhi)(zhi)(zhi)間(jian)(jian)分布電(dian)容的(de)(de)(de)影響(xiang),集-柵(zha)極(ji)(ji)之(zhi)(zhi)(zhi)間(jian)(jian)的(de)(de)(de)du/dt增大時(shi)(shi),其通(tong)(tong)過(guo)(guo)分布電(dian)容形(xing)成的(de)(de)(de)電(dian)流經過(guo)(guo),所以,要克(ke)服(fu)集-柵(zha)極(ji)(ji)之(zhi)(zhi)(zhi)間(jian)(jian)的(de)(de)(de)du/dt,確保穩壓(ya)(ya)管(guan)不過(guo)(guo)壓(ya)(ya),避免(mian)IGBT誤導通(tong)(tong)。克(ke)服(fu)du/dt的(de)(de)(de)方法有二種：一(yi)是驅動電(dian)路輸出與IGBT柵(zha)-射(she)極(ji)(ji)之(zhi)(zhi)(zhi)間(jian)(jian)的(de)(de)(de)連線采用雙絞屏蔽電(dian)纜,屏蔽層接地,二是采用快(kuai)速吸收電(dian)路吸收過(guo)(guo)電(dian)壓(ya)(ya)。

2.3 EXB841的過流保護功(gong)能擴展(zhan)

　　EXB841自身具(ju)有過流保(bao)護(hu)功能,其(qi)保(bao)護(hu)原理是利(li)用IGBT的(de)(de)集電極(ji)通(tong)態(tai)飽和壓降(jiang)與集電極(ji)電流呈近似線(xian)性關(guan)系。當IGBT工作(zuo)(zuo)在(zai)正(zheng)常狀態(tai)時(shi),EXB841的(de)(de)6腳電位箝(qian)制在(zai)8 V,內部(bu)保(bao)護(hu)不動(dong)作(zuo)(zuo),當IGBT因承受過流而退(tui)出(chu)飽和狀態(tai)時(shi),IGBT集-射極(ji)間的(de)(de)電壓上升很多,與EXB84l的(de)(de)6引腳相連的(de)(de)快速(su)二極(ji)管(guan)截止(zhi),EXB841的(de)(de)6引腳被懸空,內部(bu)保(bao)護(hu)動(dong)作(zuo)(zuo),輸出(chu)驅動(dong)電壓慢(man)慢(man)下降(jiang),實現IGBT的(de)(de)軟關(guan)斷。

　　在實際應用中,僅靠EXB841的(de)6引腳檢(jian)測IG-BT集電(dian)極(ji)(ji)(ji)電(dian)壓來實現過(guo)流(liu)保(bao)護(hu)并不(bu)足以有效地保(bao)護(hu)IGBT,因此有必(bi)要(yao)在主電(dian)路(lu)中加(jia)接霍爾電(dian)流(liu)傳(chuan)感(gan)器(qi)來檢(jian)測電(dian)路(lu)中的(de)過(guo)流(liu),如圖6所示。過(guo)流(liu)發生后(hou),檢(jian)測電(dian)路(lu)檢(jian)測到(dao)電(dian)流(liu),延(yan)時(shi)8μs后(hou)信號還存在的(de)話(hua)。驅動(dong)信號以關斷IGBT。在圖中,霍爾電(dian)流(liu)傳(chuan)感(gan)器(qi)如果在主電(dian)路(lu)中檢(jian)測到(dao)過(guo)流(liu)信號,其中的(de)PNP三極(ji)(ji)(ji)管(guan)將導(dao)通(tong),同時(shi),NPN三極(ji)(ji)(ji)管(guan)被(bei)截止,EXB841的(de)6腳被(bei)懸空;當(dang)沒有過(guo)流(liu)信號時(shi),PNP三極(ji)(ji)(ji)管(guan)不(bu)導(dao)通(tong),NPN三極(ji)(ji)(ji)管(guan)導(dao)通(tong),此時(shi)電(dian)路(lu)等效于擴展前的(de)電(dian)路(lu)。

3 結束語

　　本設(she)計應用以上電路(lu)對IGBT進行(xing)(xing)(xing)驅動和保護(hu)。此(ci)驅動電路(lu)是在(zai)典型驅動電路(lu)的(de)(de)基礎上進行(xing)(xing)(xing)改(gai)進和完(wan)(wan)善(shan)(shan)的(de)(de),并且自行(xing)(xing)(xing)設(she)計了隔離部(bu)分和過(guo)電流保護(hu)擴展部(bu)分。此(ci)驅動電路(lu)相對簡單(dan)、實用,對被驅動的(de)(de)IGBT有完(wan)(wan)善(shan)(shan)的(de)(de)保護(hu)能力,輸(shu)出(chu)阻抗低,具有較強的(de)(de)抗干擾性能。

　　應用這(zhe)種IGBT模(mo)塊的有(you)源(yuan)濾(lv)波器的樣機通過試驗,證明硬件能夠協調配合,控制(zhi)效(xiao)果穩定、精確,并且已經批量(liang)制(zhi)板(ban)。