主(zhu)(zhu)電(dian)(dian)(dian)路(lu)(lu)是給(gei)異步電(dian)(dian)(dian)動機(ji)提供(gong)調(diao)(diao)壓(ya)(ya)調(diao)(diao)頻(pin)(pin)電(dian)(dian)(dian)源(yuan)的電(dian)(dian)(dian)力變(bian)換部分，變(bian)頻(pin)(pin)器(qi)的主(zhu)(zhu)電(dian)(dian)(dian)路(lu)(lu)大體(ti)上可(ke)分為(wei)兩(liang)類：電(dian)(dian)(dian)壓(ya)(ya)型是將電(dian)(dian)(dian)壓(ya)(ya)源(yuan)的直(zhi)流(liu)變(bian)換為(wei)交流(liu)的變(bian)頻(pin)(pin)器(qi)，直(zhi)流(liu)回路(lu)(lu)的濾波是電(dian)(dian)(dian)容(rong)。電(dian)(dian)(dian)流(liu)型是將電(dian)(dian)(dian)流(liu)源(yuan)的直(zhi)流(liu)變(bian)換為(wei)交流(liu)的變(bian)頻(pin)(pin)器(qi)，其直(zhi)流(liu)回路(lu)(lu)濾波是電(dian)(dian)(dian)感。 它由(you)三部分構成，將工頻(pin)(pin)電(dian)(dian)(dian)源(yuan)變(bian)換為(wei)直(zhi)流(liu)功率的“整流(liu)器(qi)”，吸收在變(bian)流(liu)器(qi)和逆變(bian)器(qi)產生的電(dian)(dian)(dian)壓(ya)(ya)脈動的“平波回路(lu)(lu)

      整流(liu)器

      大量使(shi)用的是二極管的變(bian)(bian)流器，它把工頻電源變(bian)(bian)換為直流電源。也可(ke)用兩(liang)組晶體管變(bian)(bian)流器構(gou)成可(ke)逆變(bian)(bian)流器，由于其(qi)功(gong)率方向可(ke)逆，可(ke)以進行再生運轉(zhuan)。

      平波(bo)回路(lu)

      在整流器(qi)整流后的(de)直流電(dian)(dian)(dian)(dian)壓中，含有(you)電(dian)(dian)(dian)(dian)源(yuan)6倍頻率(lv)的(de)脈動(dong)電(dian)(dian)(dian)(dian)壓，此外(wai)逆(ni)變(bian)器(qi)產(chan)生(sheng)的(de)脈動(dong)電(dian)(dian)(dian)(dian)流也使直流電(dian)(dian)(dian)(dian)壓變(bian)動(dong)。為了抑制電(dian)(dian)(dian)(dian)壓波動(dong)，采(cai)用電(dian)(dian)(dian)(dian)感和電(dian)(dian)(dian)(dian)容吸收脈動(dong)電(dian)(dian)(dian)(dian)壓（電(dian)(dian)(dian)(dian)流）。裝置容量(liang)小時(shi)，如果電(dian)(dian)(dian)(dian)源(yuan)和主電(dian)(dian)(dian)(dian)路(lu)構成器(qi)件有(you)余量(liang)，可以省去電(dian)(dian)(dian)(dian)感采(cai)用簡單的(de)平波回(hui)路(lu)。

      逆變器(qi)

      同整流(liu)器相反，逆(ni)變(bian)器是將直流(liu)功率(lv)(lv)變(bian)換為(wei)所(suo)要求頻率(lv)(lv)的交流(liu)功率(lv)(lv)，以所(suo)確定的時間(jian)使(shi)6個開關器件導通、關斷就可以得到(dao)3相交流(liu)輸出。以電(dian)壓型pwm逆(ni)變(bian)器為(wei)例示出開關時間(jian)和(he)電(dian)壓波形。

      控(kong)制電(dian)(dian)路(lu)是給(gei)異步(bu)電(dian)(dian)動(dong)機(ji)(ji)供(gong)電(dian)(dian)（電(dian)(dian)壓(ya)、頻率可調）的(de)(de)主電(dian)(dian)路(lu)提供(gong)控(kong)制信號的(de)(de)回路(lu)，它有頻率、電(dian)(dian)壓(ya)的(de)(de)“運算電(dian)(dian)路(lu)”，主電(dian)(dian)路(lu)的(de)(de)“電(dian)(dian)壓(ya)、電(dian)(dian)流檢(jian)測(ce)電(dian)(dian)路(lu)”，電(dian)(dian)動(dong)機(ji)(ji)的(de)(de)“速(su)度檢(jian)測(ce)電(dian)(dian)路(lu)”，將(jiang)運算電(dian)(dian)路(lu)的(de)(de)控(kong)制信號進行(xing)放大的(de)(de)“驅動(dong)電(dian)(dian)路(lu)”，以及(ji)逆變器和電(dian)(dian)動(dong)機(ji)(ji)的(de)(de)“保護(hu)電(dian)(dian)路(lu)”組(zu)成。

      （1）運算電(dian)(dian)路：將(jiang)外部的速度、轉矩等指令同檢測電(dian)(dian)路的電(dian)(dian)流、電(dian)(dian)壓信號(hao)進行比較運算，決定逆變器的輸(shu)出(chu)電(dian)(dian)壓、頻(pin)率。

      （2）電(dian)壓、電(dian)流檢(jian)測(ce)電(dian)路(lu)：與主(zhu)回路(lu)電(dian)位隔離(li)檢(jian)測(ce)電(dian)壓、電(dian)流等(deng)。

      （3）驅動(dong)電路(lu)：驅動(dong)主電路(lu)器(qi)件的(de)電路(lu)。它與控制電路(lu)隔(ge)離使主電路(lu)器(qi)件導通、關斷。

      （4）速度(du)檢測電路:以裝(zhuang)在異步(bu)電動(dong)機軸(zhou)機上的(de)速度(du)檢測器(tg、plg等(deng))的(de)信號(hao)為(wei)速度(du)信號(hao)，送入(ru)運(yun)算(suan)回路，根據指(zhi)令和運(yun)算(suan)可(ke)使電動(dong)機按(an)指(zhi)令速度(du)運(yun)轉。

      （5）保護電(dian)(dian)(dian)路(lu)：檢測(ce)主(zhu)電(dian)(dian)(dian)路(lu)的電(dian)(dian)(dian)壓(ya)、電(dian)(dian)(dian)流等(deng)，當(dang)發(fa)生過載或過電(dian)(dian)(dian)壓(ya)等(deng)異常時(shi)，為(wei)了防止逆(ni)變器和(he)異步電(dian)(dian)(dian)動機損壞(huai)