變頻調速的優點：

　　1、調速(su)的效(xiao)率高(gao)，屬于(yu)g效(xiao)調速(su)方式。這是由(you)于(yu)在頻(pin)率變(bian)化(hua)后，電動機(ji)(ji)仍在同(tong)步轉速(su)附近運(yun)行，基本保(bao)持額定(ding)轉差。只是在變(bian)頻(pin)裝(zhuang)置(zhi)系統中(zhong)會產生變(bian)流損失，以及(ji)由(you)于(yu)高(gao)次諧波的影響(xiang)，電動機(ji)(ji)的損耗增加，從而效(xiao)率有(you)所下降。

　　2、調(diao)速(su)范(fan)圍(wei)寬，一(yi)般可(ke)達(da)20:1，并在整個調(diao)速(su)范(fan)圍(wei)內具有高的(de)(de)調(diao)速(su)的(de)(de)效率(lv)。所以變頻調(diao)速(su)適用于調(diao)速(su)范(fan)圍(wei)寬，且(qie)經常(chang)處于低負荷狀態下(xia)運行的(de)(de)場(chang)合。

　　3、機械特(te)性較(jiao)硬，在(zai)無自(zi)動(dong)控(kong)制時，轉(zhuan)速變(bian)化率(lv)在(zai)5%以下(xia);當(dang)采用自(zi)動(dong)控(kong)制時，能做高精度運行，把轉(zhuan)速波(bo)動(dong)率(lv)控(kong)制在(zai)0.5%|~1%左右。

　　4、變頻裝置萬一發(fa)生故障(zhang)，可以退(tui)出運行，改(gai)由電網(wang)直接供電，泵(beng)或風機仍(reng)可繼續保持運轉。

　　5、能(neng)兼(jian)作啟(qi)(qi)(qi)動(dong)(dong)(dong)設備，即通過(guo)變頻(pin)電(dian)(dian)(dian)(dian)(dian)源將電(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)啟(qi)(qi)(qi)動(dong)(dong)(dong)到某一轉速，再斷開變頻(pin)電(dian)(dian)(dian)(dian)(dian)源，電(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)可直接(jie)接(jie)到工(gong)頻(pin)電(dian)(dian)(dian)(dian)(dian)源使泵或風機(ji)加速到全速。在變頻(pin)電(dian)(dian)(dian)(dian)(dian)源向(xiang)工(gong)頻(pin)電(dian)(dian)(dian)(dian)(dian)源切(qie)換時(shi)，一般有400%~500%的(de)沖(chong)擊電(dian)(dian)(dian)(dian)(dian)流產生(sheng)，電(dian)(dian)(dian)(dian)(dian)網(wang)電(dian)(dian)(dian)(dian)(dian)壓瞬時(shi)下(xia)降，電(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)受(shou)到機(ji)械沖(chong)擊。為(wei)了避(bi)免這(zhe)種現象的(de)產生(sheng)，可在電(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)和工(gong)頻(pin)電(dian)(dian)(dian)(dian)(dian)源之間(jian)并(bing)聯一個(ge)啟(qi)(qi)(qi)動(dong)(dong)(dong)電(dian)(dian)(dian)(dian)(dian)抗器，以便在啟(qi)(qi)(qi)動(dong)(dong)(dong)時(shi)y制沖(chong)擊電(dian)(dian)(dian)(dian)(dian)流的(de)產生(sheng)。若原(yuan)動(dong)(dong)(dong)機(ji)為(wei)同步電(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)，則需進行(xing)“同步切(qie)換”。

　　變頻調速的缺點

　　1、從目前看，變(bian)頻器的初投資太高(gao)，是(shi)應(ying)用于泵或風機(ji)調速節能中的主要障礙。但隨著電子技術的發展(zhan)，產品成本逐步提高(gao)，其應(ying)用前景日益廣闊。

　　2、因變頻(pin)器輸出(chu)的(de)電(dian)流或(huo)電(dian)壓的(de)波(bo)形為非正弦(xian)波(bo)而產(chan)生的(de)高次諧(xie)波(bo)，對電(dian)動機及電(dian)源會產(chan)生種種不良影響。若采(cai)用PWM型變頻(pin)器或(huo)采(cai)用多重化技(ji)術的(de)電(dian)流型變頻(pin)器，則這個問題(ti)可以(yi)得到大(da)大(da)的(de)改善。