? ?1、變頻器低電壓主要是指中間直流回路的低電壓，一般能引起中間直流回路的低電壓的原因來自兩個方面：

???（?1）、來自(zi)電源(yuan)輸入側的低電壓

? ? 正常情況下的(de)電(dian)(dian)(dian)源(yuan)電(dian)(dian)(dian)壓(ya)(ya)380V，允許誤差為-15%~10%，經三相(xiang)橋式(shi)全波(bo)(bo)整流(liu)后中間(jian)直流(liu)的(de)電(dian)(dian)(dian)壓(ya)(ya)值(zhi)為513V，個別情況下電(dian)(dian)(dian)源(yuan)線電(dian)(dian)(dian)壓(ya)(ya)較(jiao)小的(de)電(dian)(dian)(dian)壓(ya)(ya)波(bo)(bo)動(dong)，也不會(hui)造成變(bian)頻器(qi)的(de)低(di)電(dian)(dian)(dian)壓(ya)(ya)跳閘，只有(you)電(dian)(dian)(dian)網電(dian)(dian)(dian)壓(ya)(ya)有(you)效值(zhi)介于額定值(zhi)的(de)80%~85%之間(jian)，并(bing)且持(chi)續時間(jian)達一(yi)個周(zhou)期以上，才會(hui)引起變(bian)頻器(qi)動(dong)作。電(dian)(dian)(dian)源(yuan)輸入側的(de)低(di)電(dian)(dian)(dian)壓(ya)(ya)主(zhu)(zhu)要是由于電(dian)(dian)(dian)網電(dian)(dian)(dian)壓(ya)(ya)的(de)波(bo)(bo)動(dong)或(huo)主(zhu)(zhu)電(dian)(dian)(dian)力(li)線路切換、雷(lei)擊(ji)使電(dian)(dian)(dian)源(yuan)正弦波(bo)(bo)幅值(zhi)受影(ying)響、電(dian)(dian)(dian)廠(chang)本身的(de)變(bian)壓(ya)(ya)器(qi)超(chao)載或(huo)負荷不平衡等。

???（?2）、來自負載側的低(di)電壓

? ? 這方面的(de)原因主要(yao)是(shi)大型設(she)備啟(qi)(qi)動和(he)應用、線路過載或啟(qi)(qi)動大型電(dian)(dian)(dian)(dian)(dian)動機(ji)等。變頻(pin)(pin)器(qi)(qi)是(shi)由整流器(qi)(qi)和(he)逆(ni)變器(qi)(qi)兩部分組(zu)成。通過對(dui)變頻(pin)(pin)器(qi)(qi)的(de)研(yan)究，變頻(pin)(pin)器(qi)(qi)低(di)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)指(zhi)其中間(jian)直流回路低(di)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(即(ji)逆(ni)變器(qi)(qi)輸入(ru)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)過低(di))。一(yi)般(ban)的(de)變頻(pin)(pin)器(qi)(qi)都具有(you)過壓(ya)(ya)、失(shi)(shi)壓(ya)(ya)和(he)瞬間(jian)停(ting)(ting)(ting)(ting)(ting)(ting)(ting)電(dian)(dian)(dian)(dian)(dian)的(de)保(bao)護功能(neng)(neng)。變頻(pin)(pin)器(qi)(qi)的(de)逆(ni)變器(qi)(qi)件分為GTR和(he)IGBT兩種(zhong)，變頻(pin)(pin)器(qi)(qi)的(de)逆(ni)變器(qi)(qi)件為GTR時(shi)，一(yi)旦失(shi)(shi)壓(ya)(ya)或停(ting)(ting)(ting)(ting)(ting)(ting)(ting)電(dian)(dian)(dian)(dian)(dian)，控(kong)制(zhi)(zhi)電(dian)(dian)(dian)(dian)(dian)路將停(ting)(ting)(ting)(ting)(ting)(ting)(ting)止向驅動電(dian)(dian)(dian)(dian)(dian)路輸出信號，使(shi)驅動電(dian)(dian)(dian)(dian)(dian)路和(he)GTR全部停(ting)(ting)(ting)(ting)(ting)(ting)(ting)止工作，電(dian)(dian)(dian)(dian)(dian)動機(ji)將處(chu)于(yu)自由制(zhi)(zhi)動狀態。逆(ni)變器(qi)(qi)件為IGBT時(shi)，在失(shi)(shi)壓(ya)(ya)或停(ting)(ting)(ting)(ting)(ting)(ting)(ting)電(dian)(dian)(dian)(dian)(dian)后，將允許變頻(pin)(pin)器(qi)(qi)繼(ji)續工作一(yi)個短時(shi)間(jian)td，若失(shi)(shi)壓(ya)(ya)或停(ting)(ting)(ting)(ting)(ting)(ting)(ting)電(dian)(dian)(dian)(dian)(dian)時(shi)間(jian)totd，變頻(pin)(pin)器(qi)(qi)自我(wo)保(bao)護停(ting)(ting)(ting)(ting)(ting)(ting)(ting)止運(yun)行(xing)。一(yi)般(ban)td都在15～25ms,而(er)電(dian)(dian)(dian)(dian)(dian)源“晃電(dian)(dian)(dian)(dian)(dian)”時(shi)間(jian)to一(yi)般(ban)都在幾秒鐘(zhong)以上，變頻(pin)(pin)器(qi)(qi)均(jun)會自我(wo)保(bao)護停(ting)(ting)(ting)(ting)(ting)(ting)(ting)止運(yun)行(xing)，使(shi)電(dian)(dian)(dian)(dian)(dian)動機(ji)停(ting)(ting)(ting)(ting)(ting)(ting)(ting)止運(yun)行(xing)。因此解決變頻(pin)(pin)器(qi)(qi)低(di)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)跳(tiao)閘問題不能(neng)(neng)從變頻(pin)(pin)器(qi)(qi)固有(you)時(shi)間(jian)td和(he)失(shi)(shi)壓(ya)(ya)時(shi)間(jian)to入(ru)手(shou)(shou)，而(er)必須從能(neng)(neng)夠(gou)承受降壓(ya)(ya)的(de)幅(fu)值著手(shou)(shou)。

??? 2、變頻器低電壓跳閘解決方法：

? ? 解決變頻(pin)器(qi)低電壓跳(tiao)閘問(wen)題要掌(zhang)握好兩個關(guan)鍵點：

?（1）是要選擇具(ju)備IGBT逆(ni)變器(qi)(qi)件的(de)變頻器(qi)(qi);

? （2）是要選(xuan)擇在(zai)大幅度失(shi)壓(ya)條件(jian)下仍能正常工作的(de)變(bian)頻器(qi)。

? ? 電動機能(neng)夠旋轉，但(dan)運行電流(liu)超過了額定值(zhi)，稱為(wei)過載。過載的基(ji)本反(fan)映是(shi)：電流(liu)雖然超過了額定值(zhi)，但(dan)超過的幅度不(bu)大，一般也(ye)不(bu)形(xing)成較大的沖(chong)擊電流(liu)。

? ??變頻器過載跳閘的(de)原(yuan)因及檢(jian)查方法?

??? 1、變頻器過載的主要原因

? ?（1）誤動作，變頻(pin)器內部的電流(liu)檢測(ce)部分發生(sheng)故障，檢測(ce)出的電流(liu)信號偏(pian)大，導致跳閘。

? ?（2）機械(xie)負荷(he)(he)過重(zhong)，負荷(he)(he)過重(zhong)的主要特征(zheng)是電(dian)動機發熱，并可(ke)從(cong)顯示(shi)屏上讀(du)取運(yun)行電(dian)流來發現。

? ?（3）三相電壓不平衡，引起某相的運(yun)行(xing)電流過大，導(dao)致過載跳閘，其特(te)點是電動(dong)機發熱不均衡，從顯示屏(ping)上讀取(qu)運(yun)行(xing)電流時不一定(ding)能發現(因顯示屏(ping)只顯示一相電流)。

??? 2、變頻器是否過載的檢查方法

? （1）檢(jian)查電(dian)動機側三(san)相(xiang)電(dian)壓是(shi)否平衡(heng)(heng)，如果電(dian)動機側的三(san)相(xiang)電(dian)壓不平衡(heng)(heng)，則(ze)應再檢(jian)查變頻器輸出端的三(san)相(xiang)電(dian)壓是(shi)否平衡(heng)(heng)，如也不平衡(heng)(heng)，則(ze)問題(ti)在變頻器內部。

? ? 如(ru)變(bian)(bian)頻器(qi)(qi)輸出端的電(dian)壓平衡，則(ze)問題在(zai)從變(bian)(bian)頻器(qi)(qi)到電(dian)動(dong)機之間的線(xian)路上，應檢(jian)查所有接(jie)線(xian)端的螺釘是否(fou)都已擰(ning)緊，如(ru)果在(zai)變(bian)(bian)頻器(qi)(qi)和電(dian)動(dong)機之間有接(jie)觸(chu)器(qi)(qi)或其他電(dian)器(qi)(qi)，則(ze)還應檢(jian)查有關電(dian)器(qi)(qi)的接(jie)線(xian)端是否(fou)都已擰(ning)緊，以及觸(chu)點的接(jie)觸(chu)狀況是否(fou)良(liang)好等(deng)。

? ? 如果電(dian)動機側三(san)相(xiang)電(dian)壓(ya)平衡，則應了(le)解跳閘時的(de)工(gong)(gong)作(zuo)(zuo)頻率(lv)：如工(gong)(gong)作(zuo)(zuo)頻率(lv)較(jiao)低(di)，又未用矢(shi)量控制(或無矢(shi)量控制)，則首先降低(di)U/f比，如果降低(di)后仍能帶(dai)動負載，則說明原來預置的(de)U/f比過高，勵磁電(dian)流(liu)的(de)峰值(zhi)偏大，可通(tong)過降低(di)U/f比來減小(xiao)電(dian)流(liu);

? ? 如(ru)果(guo)降(jiang)低(di)后帶不動負載了(le)，則應考慮加大變頻(pin)器的容量(liang);如(ru)果(guo)變頻(pin)器具有矢量(liang)控制功能(neng)，則應采(cai)用矢量(liang)控制方(fang)式。

? ? （2）檢查(cha)電動機是(shi)否發熱，如果電動機的溫(wen)升不高，則(ze)首(shou)先應檢查(cha)變頻(pin)器的電子熱保護功(gong)能預置(zhi)得(de)是(shi)否合(he)理，如變頻(pin)器尚有余量(liang)，則(ze)應放寬電子熱保護功(gong)能的預置(zhi)值。

? ? 如果電動(dong)機(ji)(ji)的溫升過高(gao)，而所出現(xian)的過載又屬(shu)于(yu)正常過載，則(ze)說明是電動(dong)機(ji)(ji)的負(fu)荷過重。這時(shi)，首先應能(neng)否適當加(jia)(jia)大傳動(dong)比，以減輕(qing)電動(dong)機(ji)(ji)軸上(shang)的負(fu)荷。如能(neng)夠加(jia)(jia)大，則(ze)加(jia)(jia)大傳動(dong)比。如果傳動(dong)比無(wu)法(fa)加(jia)(jia)大，則(ze)應加(jia)(jia)大電動(dong)機(ji)(ji)的容(rong)量。