高壓變頻器和(he)低壓變頻器有(you)什(shen)么區別?又(you)有(you)什(shen)么聯系(xi)呢?下(xia)面，小編就(jiu)為大家詳細介紹(shao)一下(xia)：

　　1、高壓(ya)(ya)變(bian)頻(pin)器與低壓(ya)(ya)變(bian)頻(pin)器的區別(bie)在(zai)哪里呢?

　　變(bian)頻器大體上可分為(wei)兩類(lei)：高壓變(bian)頻器和低壓變(bian)頻器。

　　從用途來講，適(shi)用對(dui)象不一樣，高壓(ya)電機從調(diao)速原理來講，二者都是(shi)一樣的。從拓撲結構看，二者差別很大(da)，主要是(shi)因為目(mu)前廣泛應用的IGBT模塊耐壓(ya)不足造成(cheng)的。高壓(ya)變頻器由于電壓(ya)高，對(dui)驅動電路等的干(gan)擾(rao)也大(da)，通常(chang)都采用的光(guang)纖進行隔離。

　　2、為什么變(bian)頻器的輸(shu)出電(dian)壓與頻率成比例的改變(bian)?

　　異(yi)步電(dian)(dian)動(dong)機(ji)(ji)(ji)的(de)(de)(de)轉矩是電(dian)(dian)機(ji)(ji)(ji)的(de)(de)(de)磁(ci)通(tong)與(yu)轉子(zi)內流(liu)過的(de)(de)(de)電(dian)(dian)流(liu)之間相互(hu)作用而產(chan)生的(de)(de)(de)，在額定(ding)頻(pin)率(lv)(lv)下，如果電(dian)(dian)壓(ya) 而只降低頻(pin)率(lv)(lv)，那么磁(ci)通(tong)就過大，磁(ci)回路飽(bao)和，電(dian)(dian)機(ji)(ji)(ji)電(dian)(dian)流(liu) ，嚴重時(shi)將燒(shao)毀電(dian)(dian)機(ji)(ji)(ji)。因此(ci)，頻(pin)率(lv)(lv)與(yu)電(dian)(dian)壓(ya)要成比例(li)地改變，即(ji)改變頻(pin)率(lv)(lv)的(de)(de)(de)同時(shi)控制變頻(pin)器(qi)的(de)(de)(de)輸(shu)出電(dian)(dian)壓(ya)，使電(dian)(dian)動(dong)機(ji)(ji)(ji)的(de)(de)(de)磁(ci)通(tong)保(bao)持 ，避(bi)免磁(ci)飽(bao)和現象的(de)(de)(de)產(chan)生。這(zhe)就是VVVF的(de)(de)(de)定(ding)義。這(zhe)里的(de)(de)(de)電(dian)(dian)壓(ya)指的(de)(de)(de)是電(dian)(dian)機(ji)(ji)(ji)的(de)(de)(de)線電(dian)(dian)壓(ya)或者相電(dian)(dian)壓(ya)的(de)(de)(de) 值。

　　3、電動(dong)機使用工頻電源(yuan)驅動(dong)時，電壓下降(jiang)(jiang)則電流增(zeng)加;對于變(bian)頻器驅動(dong)，如果頻率(lv)下降(jiang)(jiang)時電壓也下降(jiang)(jiang)，那么電流是否增(zeng)加?

　　頻(pin)率下(xia)降(低速)時,如果輸出(chu)相同(tong)的功率,則電(dian)流(liu)增加，但在轉矩 的條件下(xia),電(dian)流(liu)幾乎(hu)不變。

　　4、采用變頻器運轉時，電機的起動電流、起動轉矩怎樣?

　　采用(yong)變頻器(qi)運轉，隨著電(dian)(dian)機(ji)的(de)加(jia)速相(xiang)應提高(gao)頻率和電(dian)(dian)壓，起(qi)(qi)動(dong)(dong)電(dian)(dian)流(liu)(liu)被限制(zhi)在(zai)150%額定(ding)電(dian)(dian)流(liu)(liu)以(yi)下(根據(ju)機(ji)種(zhong)不同，為(wei)(wei)125%～200%)。用(yong)工頻電(dian)(dian)源直接(jie)起(qi)(qi)動(dong)(dong)時，起(qi)(qi)動(dong)(dong)電(dian)(dian)流(liu)(liu)為(wei)(wei)6～7倍，因此，將產生機(ji)械電(dian)(dian)氣(qi)上的(de)沖擊。采用(yong)變頻器(qi)傳動(dong)(dong)可以(yi)平(ping)滑地起(qi)(qi)動(dong)(dong)(起(qi)(qi)動(dong)(dong)時間變長)。起(qi)(qi)動(dong)(dong)電(dian)(dian)流(liu)(liu)為(wei)(wei)額定(ding)電(dian)(dian)流(liu)(liu)的(de)1.2～1.5倍，起(qi)(qi)動(dong)(dong)轉矩為(wei)(wei)70%～120%額定(ding)轉矩;對(dui)于(yu)帶有(you)轉矩自(zi)動(dong)(dong) 功(gong)能(neng)的(de)變頻器(qi)，起(qi)(qi)動(dong)(dong)轉矩為(wei)(wei) 以(yi)上，可以(yi)帶全負載(zai)起(qi)(qi)動(dong)(dong)。

　　5、V/f模式是什么意思?

　　頻(pin)率下降時電(dian)(dian)(dian)壓(ya)V也成(cheng)比例(li)下降，這個問題已(yi)在回答(da)4說(shuo)明。保(bao)持V/f比恒定控(kong)制(zhi)是異步電(dian)(dian)(dian)機(ji)變(bian)頻(pin)調速的 基本的控(kong)制(zhi)方式，它在控(kong)制(zhi)電(dian)(dian)(dian)機(ji)的電(dian)(dian)(dian)源頻(pin)率變(bian)化(hua)的同時控(kong)制(zhi)變(bian)頻(pin)器輸出(chu)的電(dian)(dian)(dian)壓(ya)，并使二者(zhe)之比V/f為恒定，從而使電(dian)(dian)(dian)機(ji)的磁(ci)通保(bao)持恒定。在電(dian)(dian)(dian)機(ji)額定運行情(qing)況下，電(dian)(dian)(dian)機(ji)的定子電(dian)(dian)(dian)阻和(he)漏抗的電(dian)(dian)(dian)壓(ya)降比較小，電(dian)(dian)(dian)機(ji)的端(duan)電(dian)(dian)(dian)壓(ya)和(he)電(dian)(dian)(dian)機(ji)的感應電(dian)(dian)(dian)勢近似相等。

　　V/f比(bi)(bi)恒定(ding)(ding)控(kong)制存在的(de)主要問題是(shi)(shi)低速性能(neng)較差。其原因一是(shi)(shi)低速時異步電(dian)(dian)(dian)機(ji)(ji)(ji)定(ding)(ding)子(zi)電(dian)(dian)(dian)阻電(dian)(dian)(dian)壓降所(suo)占比(bi)(bi)例變(bian)大，已不(bu)能(neng)忽略，不(bu)能(neng)再認為定(ding)(ding)子(zi)電(dian)(dian)(dian)壓和(he)電(dian)(dian)(dian)機(ji)(ji)(ji)感應電(dian)(dian)(dian)勢近似(si)相等，仍按V/f比(bi)(bi) 控(kong)制已不(bu)能(neng)保持電(dian)(dian)(dian)機(ji)(ji)(ji)磁通(tong)恒定(ding)(ding)。電(dian)(dian)(dian)機(ji)(ji)(ji)磁通(tong)的(de)減小(xiao)必然造(zao)(zao)成電(dian)(dian)(dian)機(ji)(ji)(ji)的(de)電(dian)(dian)(dian)磁轉矩減小(xiao);另外變(bian)頻器(qi)功(gong)率(lv)器(qi)件的(de) 區(qu)時間也是(shi)(shi)影響電(dian)(dian)(dian)機(ji)(ji)(ji)低速性能(neng)的(de)重(zhong)要原因， 區(qu)時間造(zao)(zao)成電(dian)(dian)(dian)壓下降同(tong)時還(huan)會引起轉矩脈動，在 條(tiao)件下還(huan)會引起轉速、電(dian)(dian)(dian)流(liu)的(de)振蕩。

　　V/f比恒(heng)(heng)定控制常用于(yu)(yu)通用變頻器(qi)上(shang)。這類變頻器(qi)主(zhu)要(yao)用于(yu)(yu)風機、水(shui)泵的調速功能，以及對(dui)調速范圍要(yao)求(qiu)不高的場(chang)合。V/f比恒(heng)(heng)定控制的突出(chu)優點是(shi)可以進行(xing)電(dian)機的開環速度控制。

　　6、按比例地改V和(he)f時(shi)，電機的轉矩如何(he)變化?

　　頻(pin)率下降(jiang)(jiang)時(shi) 成比例地降(jiang)(jiang)低(di)電壓(ya)，那么由于交(jiao)流阻抗變(bian)小(xiao)而電阻不變(bian)，將造成在低(di)速下產生的轉(zhuan)矩有減小(xiao)的傾向。因此(ci)，在低(di)頻(pin)時(shi)給定V/f,要使輸出電壓(ya)提(ti)高(gao)一些,以便獲得 的起動(dong)轉(zhuan)矩,這種(zhong)(zhong)補償稱 起動(dong)。可以采(cai)用各種(zhong)(zhong)方(fang)法實現,有自動(dong)進行(xing)的方(fang)法、選(xuan)擇V/f模式(shi)或調整電位器等方(fang)法。

　　7、所謂開環是什(shen)么意思?

　　給所(suo)使用(yong)的(de)電(dian)機(ji)裝(zhuang)(zhuang)設速(su)(su)度傳(chuan)感器(qi)，將(jiang)實際(ji)轉速(su)(su)反(fan)饋給控制(zhi)裝(zhuang)(zhuang)置進行控制(zhi)的(de)，稱為(wei)“閉環(huan)”，不用(yong)速(su)(su)度傳(chuan)感器(qi)運(yun)轉的(de)就叫(jiao)作“開環(huan)”，通用(yong)變頻器(qi)多為(wei)開環(huan)方式。

　　8、高壓變頻器自身的保護功能(neng)

　　輸(shu)出過(guo)載(zai)、輸(shu)出過(guo)流、電(dian)(dian)(dian)(dian)網(wang)過(guo)電(dian)(dian)(dian)(dian)壓(ya)、電(dian)(dian)(dian)(dian)網(wang)欠(qian)電(dian)(dian)(dian)(dian)壓(ya)、電(dian)(dian)(dian)(dian)網(wang)失電(dian)(dian)(dian)(dian)、直流母線(xian)過(guo)電(dian)(dian)(dian)(dian)壓(ya)、直流母線(xian)欠(qian)電(dian)(dian)(dian)(dian)壓(ya)、變壓(ya)器(qi)過(guo)熱(re)、缺相、控制電(dian)(dian)(dian)(dian)源掉電(dian)(dian)(dian)(dian)、驅動故障、功率器(qi)件過(guo)熱(re)、散熱(re)風機故障、外部給定(ding)掉線(xian)、接地故障、光(guang)纖故障等(deng)等(deng)