高低溫試驗箱功率因數校正方法

在(zai)高低溫試驗箱中，若采用單相交流(liu)(liu)，一般經過不(bu)可控(kong)橋式整流(liu)(liu)，將(jiang)交流(liu)(liu)電源(yuan)整流(liu)(liu)成(cheng)直(zhi)流(liu)(liu)電源(yuan)(接大容(rong)量電(dian)解電(dian)容(rong))來驅動壓縮機。然而，不可控整(zheng)流(liu)導(dao)致整(zheng)機功率因(yin)數(shu)很低(di)、電流(liu)諧(xie)波很高，難以滿足(zu)電流(liu)諧(xie)波標準IEC 61000-3-2。因此，必(bi)須在(zai)整流(liu)后，電(dian)解(jie)電(dian)容前增(zeng)加功率因數校正(zheng)(Power factor correction, PFC)電路，提(ti)高系統的功(gong)率因數(shu)、減小輸入(ru)電流諧(xie)波。

功率因(yin)數(shu)(shu)校正電路可分為無源(yuan)功率因(yin)數(shu)(shu)校正(Passive PFC)方(fang)法和(he)有源功率因數校正(Active PFC)方法(fa)。其中，Boost升壓型功率(lv)因數(shu)(shu)校(xiao)正電路，不僅能(neng)夠提高(gao)高(gao)低溫(wen)試驗(yan)箱(xiang)的功率(lv)因數(shu)(shu)，而且能(neng)起到(dao)提升流(liu)母線電壓的作用，更加利于高(gao)低溫(wen)試驗(yan)箱(xiang)的高(gao)頻運行，故而成(cheng)為單相高(gao)低溫(wen)試驗(yan)箱(xiang)有源功率(lv)因數(shu)(shu)校(xiao)正主流(liu)解決方案(an)。

Boost升壓(ya)(ya)型(xing)功(gong)(gong)率(lv)因(yin)數校(xiao)正的(de)控(kong)制(zhi)(zhi)(zhi)方(fang)法(fa)主要(yao)(yao)兩種：一(yi)種是(shi)基于(yu)(yu)直(zhi)流母線電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)、輸(shu)(shu)入(ru)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)和輸(shu)(shu)入(ru)電(dian)(dian)(dian)(dian)(dian)流檢測的(de)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)電(dian)(dian)(dian)(dian)(dian)流雙閉環(huan)控(kong)制(zhi)(zhi)(zhi)方(fang)法(fa)，另一(yi)種是(shi)基于(yu)(yu)直(zhi)流母線電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)和輸(shu)(shu)入(ru)電(dian)(dian)(dian)(dian)(dian)流檢測的(de)單(dan)周(zhou)期(qi)控(kong)制(zhi)(zhi)(zhi)方(fang)法(fa)。其中，單(dan)周(zhou)期(qi)控(kong)制(zhi)(zhi)(zhi)方(fang)法(fa)不(bu)需要(yao)(yao)檢測輸(shu)(shu)入(ru)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)，能(neng)夠降低系統硬(ying)件成本，故(gu)而(er)成為設計的(de)首選。但(dan)是(shi)，在功(gong)(gong)率(lv)因(yin)數校(xiao)正開啟時刻，由于(yu)(yu)初始(shi)占(zhan)空(kong)比不(bu)定(ding)，在輸(shu)(shu)入(ru)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)較高(gao)時，較大(da)的(de)占(zhan)空(kong)比必然造(zao)成電(dian)(dian)(dian)(dian)(dian)流超調沖擊，進耐導(dao)致過流保護而(er)故(gu)障(zhang)停機(ji)，甚至損壞(huai)試驗箱的(de)硬(ying)件電(dian)(dian)(dian)(dian)(dian)路(lu)。因(yin)此，功(gong)(gong)率(lv)因(yin)數校(xiao)正需要(yao)(yao)在輸(shu)(shu)入(ru)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)過零點(dian)。

由于(yu)采用單(dan)周期(qi)控制的Boost升(sheng)壓(ya)(ya)型功率因數校正(zheng)電(dian)路時，沒(mei)有輸入電(dian)壓(ya)(ya)檢(jian)測(ce)電(dian)路，因此應該(gai)提(ti)出一種基于輸入電(dian)流的頻率與過流檢(jian)測(ce)方法(fa)。首先，根(gen)據輸入電(dian)流波形的上升(sheng)與下降進行電(dian)網電(dian)壓(ya)(ya)頻率的檢(jian)測(ce);然(ran)后，在已知(zhi)頻率的基(ji)礎(chu)上，采用輸入電流峰值閉(bi)環跟蹤的方法進行過零檢(jian)測，用于(yu)開啟(qi)PFC;同時，根據輸入電(dian)流波形可以進行電(dian)網電(dian)壓短(duan)時中斷實時偵測。該方法能(neng)夠自(zi)動適應50Hz與60Hz應用(yong)，在國(guo)內市(shi)場與海外市(shi)場通(tong)用(yong)。