1、電(dian)(dian)壓源型與(yu)電(dian)(dian)流源型高壓變頻器(qi)的區別。
變(bian)頻(pin)器(qi)(qi)的(de)(de)主電(dian)(dian)路(lu)大(da)體(ti)上可分為(wei)兩類：電(dian)(dian)壓源(yuan)(yuan)(yuan)(yuan)型(xing)和電(dian)(dian)流源(yuan)(yuan)(yuan)(yuan)型(xing)。電(dian)(dian)壓源(yuan)(yuan)(yuan)(yuan)型(xing)是(shi)將(jiang)(jiang)電(dian)(dian)壓源(yuan)(yuan)(yuan)(yuan)的(de)(de)直流變(bian)換(huan)為(wei)交(jiao)流的(de)(de)變(bian)頻(pin)器(qi)(qi)，直流回(hui)路(lu)的(de)(de)濾(lv)波元(yuan)件(jian)是(shi)電(dian)(dian)容;電(dian)(dian)流源(yuan)(yuan)(yuan)(yuan)型(xing)是(shi)將(jiang)(jiang)電(dian)(dian)流源(yuan)(yuan)(yuan)(yuan)的(de)(de)直流變(bian)換(huan)為(wei)交(jiao)流的(de)(de)變(bian)頻(pin)器(qi)(qi)，其直流回(hui)路(lu)濾(lv)波元(yuan)件(jian)是(shi)電(dian)(dian)感。
2、為什(shen)么變頻器的輸(shu)出電壓與(yu)頻率成比例的改變?
異步電(dian)(dian)(dian)(dian)(dian)動(dong)機(ji)(ji)的(de)(de)(de)(de)轉矩(ju)是(shi)(shi)電(dian)(dian)(dian)(dian)(dian)機(ji)(ji)的(de)(de)(de)(de)磁通與轉子內流(liu)過的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)流(liu)之間(jian)相互(hu)作用(yong)而產生(sheng)的(de)(de)(de)(de)，在額定頻(pin)率(lv)(lv)下，如果電(dian)(dian)(dian)(dian)(dian)壓(ya)一定而只降(jiang)低頻(pin)率(lv)(lv)，那么磁通就過大，磁回路(lu)飽和(he)，電(dian)(dian)(dian)(dian)(dian)機(ji)(ji)電(dian)(dian)(dian)(dian)(dian)流(liu)增(zeng)大，嚴重時(shi)將(jiang)燒(shao)毀電(dian)(dian)(dian)(dian)(dian)機(ji)(ji)。因此(ci)，頻(pin)率(lv)(lv)與電(dian)(dian)(dian)(dian)(dian)壓(ya)要成比(bi)例(li)地改(gai)變(bian)，即改(gai)變(bian)頻(pin)率(lv)(lv)的(de)(de)(de)(de)同時(shi)控制變(bian)頻(pin)器的(de)(de)(de)(de)輸出電(dian)(dian)(dian)(dian)(dian)壓(ya)，使電(dian)(dian)(dian)(dian)(dian)動(dong)機(ji)(ji)的(de)(de)(de)(de)磁通保持一定，避免磁飽和(he)現(xian)象的(de)(de)(de)(de)產生(sheng)。這就是(shi)(shi)VVVF的(de)(de)(de)(de)定義(yi)。這里的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)壓(ya)指的(de)(de)(de)(de)是(shi)(shi)電(dian)(dian)(dian)(dian)(dian)機(ji)(ji)的(de)(de)(de)(de)線電(dian)(dian)(dian)(dian)(dian)壓(ya)或者相電(dian)(dian)(dian)(dian)(dian)壓(ya)的(de)(de)(de)(de)有效(xiao)值。
3、電(dian)(dian)(dian)動機使(shi)用工頻電(dian)(dian)(dian)源驅(qu)動時，電(dian)(dian)(dian)壓下(xia)降(jiang)則電(dian)(dian)(dian)流增加(jia);對于變頻器驅(qu)動，如果頻率下(xia)降(jiang)時電(dian)(dian)(dian)壓也下(xia)降(jiang)，那么(me)電(dian)(dian)(dian)流是否增加(jia)?
頻率(lv)下降(jiang)(低速(su))時,如果(guo)輸(shu)出相(xiang)同的(de)功(gong)率(lv),則電流增(zeng)加(jia)，但在轉(zhuan)矩一(yi)定的(de)條(tiao)件下,電流幾乎不變。
4、采用變頻器(qi)運(yun)轉(zhuan)時，電機的起(qi)動電流、起(qi)動轉(zhuan)矩怎樣?
采用變(bian)頻(pin)器運轉(zhuan)，隨著電(dian)(dian)機的(de)加(jia)速相應(ying)提高(gao)頻(pin)率和電(dian)(dian)壓，起(qi)(qi)動(dong)電(dian)(dian)流被限制在150%額(e)定(ding)(ding)電(dian)(dian)流以下(根據機種(zhong)不同(tong)，為125%～200%)。用工頻(pin)電(dian)(dian)源(yuan)直接起(qi)(qi)動(dong)時(shi)，起(qi)(qi)動(dong)電(dian)(dian)流為6～7倍(bei)，因此，將(jiang)產生機械(xie)電(dian)(dian)氣上的(de)沖擊。采用變(bian)頻(pin)器傳(chuan)動(dong)可以平(ping)滑地起(qi)(qi)動(dong)(起(qi)(qi)動(dong)時(shi)間(jian)變(bian)長(chang))。起(qi)(qi)動(dong)電(dian)(dian)流為額(e)定(ding)(ding)電(dian)(dian)流的(de)1.2～1.5倍(bei)，起(qi)(qi)動(dong)轉(zhuan)矩(ju)為70%～120%額(e)定(ding)(ding)轉(zhuan)矩(ju);對于帶有(you)轉(zhuan)矩(ju)自(zi)動(dong)增強功能的(de)變(bian)頻(pin)器，起(qi)(qi)動(dong)轉(zhuan)矩(ju)為100%以上，可以帶全負載起(qi)(qi)動(dong)。