主(zhu)電(dian)(dian)路(lu)是(shi)(shi)給異(yi)步電(dian)(dian)動(dong)機提供調壓(ya)調頻(pin)電(dian)(dian)源(yuan)的(de)(de)(de)(de)電(dian)(dian)力(li)變(bian)(bian)換(huan)部分(fen)，變(bian)(bian)頻(pin)器(qi)(qi)的(de)(de)(de)(de)主(zhu)電(dian)(dian)路(lu)大體(ti)上可分(fen)為(wei)兩(liang)類：電(dian)(dian)壓(ya)型(xing)(xing)是(shi)(shi)將電(dian)(dian)壓(ya)源(yuan)的(de)(de)(de)(de)直流(liu)變(bian)(bian)換(huan)為(wei)交(jiao)流(liu)的(de)(de)(de)(de)變(bian)(bian)頻(pin)器(qi)(qi)，直流(liu)回(hui)路(lu)的(de)(de)(de)(de)濾波是(shi)(shi)電(dian)(dian)容。電(dian)(dian)流(liu)型(xing)(xing)是(shi)(shi)將電(dian)(dian)流(liu)源(yuan)的(de)(de)(de)(de)直流(liu)變(bian)(bian)換(huan)為(wei)交(jiao)流(liu)的(de)(de)(de)(de)變(bian)(bian)頻(pin)器(qi)(qi)，其直流(liu)回(hui)路(lu)濾波是(shi)(shi)電(dian)(dian)感。 它由三部分(fen)構成，將工頻(pin)電(dian)(dian)源(yuan)變(bian)(bian)換(huan)為(wei)直流(liu)功(gong)率的(de)(de)(de)(de)“整流(liu)器(qi)(qi)”，吸收在變(bian)(bian)流(liu)器(qi)(qi)和逆變(bian)(bian)器(qi)(qi)產生的(de)(de)(de)(de)電(dian)(dian)壓(ya)脈動(dong)的(de)(de)(de)(de)“平波回(hui)路(lu)

      整(zheng)流器

      大量使用的(de)是二(er)極管的(de)變流器，它把工頻電源(yuan)(yuan)變換(huan)為直(zhi)流電源(yuan)(yuan)。也(ye)可(ke)(ke)用兩組(zu)晶體管變流器構成可(ke)(ke)逆變流器，由于(yu)其功率方向(xiang)可(ke)(ke)逆，可(ke)(ke)以進行再生運轉(zhuan)。

      平波回路

      在整(zheng)(zheng)流(liu)器(qi)整(zheng)(zheng)流(liu)后的直(zhi)流(liu)電(dian)(dian)(dian)壓(ya)中(zhong)，含有電(dian)(dian)(dian)源6倍頻率的脈動(dong)(dong)(dong)電(dian)(dian)(dian)壓(ya)，此(ci)外逆變器(qi)產(chan)生的脈動(dong)(dong)(dong)電(dian)(dian)(dian)流(liu)也使(shi)直(zhi)流(liu)電(dian)(dian)(dian)壓(ya)變動(dong)(dong)(dong)。為了(le)抑制(zhi)電(dian)(dian)(dian)壓(ya)波動(dong)(dong)(dong)，采用電(dian)(dian)(dian)感和電(dian)(dian)(dian)容(rong)吸收(shou)脈動(dong)(dong)(dong)電(dian)(dian)(dian)壓(ya)（電(dian)(dian)(dian)流(liu)）。裝置容(rong)量小(xiao)時，如(ru)果電(dian)(dian)(dian)源和主(zhu)電(dian)(dian)(dian)路構成器(qi)件有余量，可(ke)以(yi)省去電(dian)(dian)(dian)感采用簡單的平(ping)波回(hui)路。

      逆變(bian)器(qi)

      同整流器(qi)相(xiang)反(fan)，逆變(bian)器(qi)是將直流功率(lv)變(bian)換為(wei)所(suo)要求頻率(lv)的交流功率(lv)，以(yi)(yi)所(suo)確定(ding)的時(shi)間使6個開關(guan)器(qi)件導(dao)通、關(guan)斷就(jiu)可以(yi)(yi)得到3相(xiang)交流輸(shu)出(chu)。以(yi)(yi)電壓(ya)型pwm逆變(bian)器(qi)為(wei)例示出(chu)開關(guan)時(shi)間和電壓(ya)波形。

      控制電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)是給異步電(dian)(dian)(dian)(dian)(dian)(dian)動(dong)機(ji)供(gong)電(dian)(dian)(dian)(dian)(dian)(dian)（電(dian)(dian)(dian)(dian)(dian)(dian)壓、頻率可調）的主電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)提供(gong)控制信號(hao)的回(hui)路(lu)(lu)，它有頻率、電(dian)(dian)(dian)(dian)(dian)(dian)壓的“運(yun)算電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)”，主電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)的“電(dian)(dian)(dian)(dian)(dian)(dian)壓、電(dian)(dian)(dian)(dian)(dian)(dian)流檢(jian)測電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)”，電(dian)(dian)(dian)(dian)(dian)(dian)動(dong)機(ji)的“速度檢(jian)測電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)”，將運(yun)算電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)的控制信號(hao)進行(xing)放大的“驅動(dong)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)”，以及(ji)逆(ni)變器和電(dian)(dian)(dian)(dian)(dian)(dian)動(dong)機(ji)的“保護電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)”組(zu)成。

      （1）運(yun)算(suan)電路：將(jiang)外部的(de)速(su)度、轉矩等(deng)指令同檢測電路的(de)電流、電壓(ya)信號進行比(bi)較運(yun)算(suan)，決定逆變器的(de)輸(shu)出電壓(ya)、頻率(lv)。

      （2）電(dian)壓、電(dian)流檢測電(dian)路(lu)：與主(zhu)回路(lu)電(dian)位隔(ge)離檢測電(dian)壓、電(dian)流等。

      （3）驅動(dong)電(dian)(dian)路(lu)：驅動(dong)主電(dian)(dian)路(lu)器件的電(dian)(dian)路(lu)。它與控制電(dian)(dian)路(lu)隔離使主電(dian)(dian)路(lu)器件導通、關斷。

      （4）速(su)(su)度(du)(du)檢測(ce)電路:以裝在異(yi)步電動(dong)機(ji)軸機(ji)上的(de)速(su)(su)度(du)(du)檢測(ce)器(tg、plg等)的(de)信號為速(su)(su)度(du)(du)信號，送(song)入運(yun)(yun)算(suan)回路，根(gen)據指(zhi)令和運(yun)(yun)算(suan)可(ke)使電動(dong)機(ji)按(an)指(zhi)令速(su)(su)度(du)(du)運(yun)(yun)轉。

      （5）保護電(dian)(dian)路：檢(jian)測主電(dian)(dian)路的電(dian)(dian)壓、電(dian)(dian)流等，當發生過(guo)載(zai)或過(guo)電(dian)(dian)壓等異(yi)常時，為了防止逆變(bian)器和異(yi)步電(dian)(dian)動機損壞