1、電壓源型與電流(liu)源型高(gao)壓變頻器(qi)的區別。

　　變(bian)(bian)(bian)頻器的主(zhu)電(dian)(dian)(dian)(dian)路(lu)大(da)體上可分為(wei)兩類：電(dian)(dian)(dian)(dian)壓源(yuan)(yuan)型(xing)和電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)源(yuan)(yuan)型(xing)。電(dian)(dian)(dian)(dian)壓源(yuan)(yuan)型(xing)是將電(dian)(dian)(dian)(dian)壓源(yuan)(yuan)的直(zhi)(zhi)流(liu)(liu)(liu)變(bian)(bian)(bian)換(huan)為(wei)交流(liu)(liu)(liu)的變(bian)(bian)(bian)頻器，直(zhi)(zhi)流(liu)(liu)(liu)回(hui)路(lu)的濾波(bo)元件(jian)是電(dian)(dian)(dian)(dian)容;電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)源(yuan)(yuan)型(xing)是將電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)源(yuan)(yuan)的直(zhi)(zhi)流(liu)(liu)(liu)變(bian)(bian)(bian)換(huan)為(wei)交流(liu)(liu)(liu)的變(bian)(bian)(bian)頻器，其直(zhi)(zhi)流(liu)(liu)(liu)回(hui)路(lu)濾波(bo)元件(jian)是電(dian)(dian)(dian)(dian)感。

 　　2、為什么變頻器(qi)的(de)輸(shu)出電壓與頻率成比例(li)的(de)改(gai)變?

　　異步(bu)電動機(ji)(ji)(ji)(ji)的(de)(de)轉矩是(shi)(shi)電機(ji)(ji)(ji)(ji)的(de)(de)磁(ci)(ci)通與(yu)轉子內流過的(de)(de)電流之間相(xiang)互作用(yong)而產生的(de)(de)，在(zai)額定頻率(lv)下，如果電壓(ya) 而只降低頻率(lv)，那么磁(ci)(ci)通就(jiu)過大，磁(ci)(ci)回路飽(bao)和，電機(ji)(ji)(ji)(ji)電流 ，嚴重時將燒毀(hui)電機(ji)(ji)(ji)(ji)。因此，頻率(lv)與(yu)電壓(ya)要(yao)成(cheng)比(bi)例地改變(bian)，即改變(bian)頻率(lv)的(de)(de)同時控制變(bian)頻器的(de)(de)輸出電壓(ya)，使電動機(ji)(ji)(ji)(ji)的(de)(de)磁(ci)(ci)通保持 ，避免磁(ci)(ci)飽(bao)和現象的(de)(de)產生。這就(jiu)是(shi)(shi)VVVF的(de)(de)定義。這里的(de)(de)電壓(ya)指的(de)(de)是(shi)(shi)電機(ji)(ji)(ji)(ji)的(de)(de)線(xian)電壓(ya)或者相(xiang)電壓(ya)的(de)(de) 值。

　　3、電動機(ji)使(shi)用工頻電源驅(qu)動時(shi)，電壓(ya)(ya)下(xia)降(jiang)則電流(liu)增(zeng)加(jia);對(dui)于變頻器驅(qu)動，如果頻率下(xia)降(jiang)時(shi)電壓(ya)(ya)也(ye)下(xia)降(jiang)，那么電流(liu)是否增(zeng)加(jia)?

　　頻(pin)率下降(低速)時,如(ru)果輸出相(xiang)同(tong)的功率,則電流(liu)增加(jia)，但在轉矩 的條(tiao)件(jian)下,電流(liu)幾乎不變。

　　4、采用變頻器運轉(zhuan)時，電(dian)機的起動(dong)電(dian)流(liu)、起動(dong)轉(zhuan)矩怎樣?

　　采(cai)用變頻器(qi)(qi)運轉(zhuan)，隨著電(dian)(dian)機的(de)加(jia)速相應提高頻率和電(dian)(dian)壓，起(qi)(qi)動(dong)(dong)電(dian)(dian)流被限制在150%額(e)定(ding)電(dian)(dian)流以(yi)下(根(gen)據(ju)機種不同，為(wei)125%～200%)。用工頻電(dian)(dian)源直接起(qi)(qi)動(dong)(dong)時，起(qi)(qi)動(dong)(dong)電(dian)(dian)流為(wei)6～7倍，因(yin)此，將產(chan)生(sheng)機械電(dian)(dian)氣上的(de)沖擊。采(cai)用變頻器(qi)(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)流為(wei)額(e)定(ding)電(dian)(dian)流的(de)1.2～1.5倍，起(qi)(qi)動(dong)(dong)轉(zhuan)矩(ju)為(wei)70%～120%額(e)定(ding)轉(zhuan)矩(ju);對于帶有(you)轉(zhuan)矩(ju)自動(dong)(dong) 功(gong)能的(de)變頻器(qi)(qi)，起(qi)(qi)動(dong)(dong)轉(zhuan)矩(ju)為(wei) 以(yi)上，可以(yi)帶全負載起(qi)(qi)動(dong)(dong)。

　　5、V/f模式是什么意思(si)?

　　頻率下降(jiang)時電(dian)(dian)(dian)(dian)壓(ya)(ya)V也成比(bi)例下降(jiang)，這個問(wen)題已在(zai)回答(da)4說明。保持V/f比(bi)恒定(ding)(ding)控(kong)制(zhi)是異步電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)變頻調速的(de) 基本的(de)控(kong)制(zhi)方式，它在(zai)控(kong)制(zhi)電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)的(de)電(dian)(dian)(dian)(dian)源頻率變化(hua)的(de)同時控(kong)制(zhi)變頻器輸出的(de)電(dian)(dian)(dian)(dian)壓(ya)(ya)，并使二(er)者之比(bi)V/f為恒定(ding)(ding)，從而(er)使電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)的(de)磁通保持恒定(ding)(ding)。在(zai)電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)額定(ding)(ding)運行(xing)情(qing)況下，電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)的(de)定(ding)(ding)子電(dian)(dian)(dian)(dian)阻和漏(lou)抗(kang)的(de)電(dian)(dian)(dian)(dian)壓(ya)(ya)降(jiang)比(bi)較小，電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)的(de)端電(dian)(dian)(dian)(dian)壓(ya)(ya)和電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)的(de)感應電(dian)(dian)(dian)(dian)勢近似(si)相等。