變頻調速的優點：

　　1、調速(su)的(de)效率高(gao)，屬于g效調速(su)方式。這(zhe)是由于在(zai)頻率變(bian)化后(hou)，電(dian)動機仍在(zai)同步轉速(su)附近(jin)運(yun)行，基本保持額定轉差。只是在(zai)變(bian)頻裝置系統中(zhong)會產生變(bian)流損失，以(yi)及由于高(gao)次諧波的(de)影響，電(dian)動機的(de)損耗增(zeng)加，從而(er)效率有所下降。

　　2、調(diao)速(su)范(fan)(fan)圍寬，一般可(ke)達20:1，并(bing)在(zai)整個調(diao)速(su)范(fan)(fan)圍內具有(you)高(gao)的(de)調(diao)速(su)的(de)效率(lv)。所以變頻(pin)調(diao)速(su)適用于調(diao)速(su)范(fan)(fan)圍寬，且經常處于低負荷狀(zhuang)態下(xia)運(yun)行的(de)場合。

　　3、機械特性(xing)較(jiao)硬，在無自(zi)動(dong)控(kong)制(zhi)時，轉(zhuan)速(su)變化率在5%以下;當采用自(zi)動(dong)控(kong)制(zhi)時，能做(zuo)高精度運行，把轉(zhuan)速(su)波動(dong)率控(kong)制(zhi)在0.5%|~1%左(zuo)右。

　　4、變頻裝置萬一發生(sheng)故(gu)障，可(ke)(ke)以(yi)退出運行(xing)，改由電網直接供(gong)電，泵或風機仍可(ke)(ke)繼續(xu)保持運轉。

　　5、能兼作啟(qi)(qi)動(dong)(dong)設備，即通(tong)過變頻(pin)電(dian)(dian)(dian)(dian)(dian)源(yuan)將電(dian)(dian)(dian)(dian)(dian)動(dong)(dong)機(ji)啟(qi)(qi)動(dong)(dong)到某(mou)一(yi)(yi)轉速，再斷開(kai)變頻(pin)電(dian)(dian)(dian)(dian)(dian)源(yuan)，電(dian)(dian)(dian)(dian)(dian)動(dong)(dong)機(ji)可(ke)直(zhi)接接到工頻(pin)電(dian)(dian)(dian)(dian)(dian)源(yuan)使泵或風機(ji)加速到全速。在變頻(pin)電(dian)(dian)(dian)(dian)(dian)源(yuan)向工頻(pin)電(dian)(dian)(dian)(dian)(dian)源(yuan)切換(huan)時，一(yi)(yi)般有400%~500%的沖(chong)擊電(dian)(dian)(dian)(dian)(dian)流(liu)產生，電(dian)(dian)(dian)(dian)(dian)網電(dian)(dian)(dian)(dian)(dian)壓瞬(shun)時下降，電(dian)(dian)(dian)(dian)(dian)動(dong)(dong)機(ji)受到機(ji)械沖(chong)擊。為(wei)了(le)避(bi)免這種(zhong)現象的產生，可(ke)在電(dian)(dian)(dian)(dian)(dian)動(dong)(dong)機(ji)和工頻(pin)電(dian)(dian)(dian)(dian)(dian)源(yuan)之間并聯一(yi)(yi)個啟(qi)(qi)動(dong)(dong)電(dian)(dian)(dian)(dian)(dian)抗器(qi)，以便(bian)在啟(qi)(qi)動(dong)(dong)時沖(chong)擊電(dian)(dian)(dian)(dian)(dian)流(liu)的產生。若原動(dong)(dong)機(ji)為(wei)同(tong)步電(dian)(dian)(dian)(dian)(dian)動(dong)(dong)機(ji)，則需(xu)進行“同(tong)步切換(huan)”。

　　變頻調速的缺點

　　1、從目前看，變頻器的(de)初投資太(tai)高，是應(ying)用于泵(beng)或風機調速節能中的(de)主要障礙。但隨著電子技術(shu)的(de)發展，產品成本(ben)逐(zhu)步提高，其應(ying)用前景日益廣闊(kuo)。

　　2、因變(bian)頻器輸出的(de)(de)電(dian)(dian)流(liu)或電(dian)(dian)壓的(de)(de)波(bo)形為非(fei)正弦波(bo)而產(chan)生(sheng)的(de)(de)高次諧(xie)波(bo)，對電(dian)(dian)動(dong)機及電(dian)(dian)源會產(chan)生(sheng)種(zhong)種(zhong)不良影響。若采(cai)用PWM型(xing)變(bian)頻器或采(cai)用多(duo)重化技術的(de)(de)電(dian)(dian)流(liu)型(xing)變(bian)頻器，則這個問題(ti)可以得(de)到大(da)大(da)的(de)(de)g善。