變頻調速的優點：

　　1、調速的(de)效(xiao)率(lv)(lv)高，屬(shu)于(yu)調速方式。這(zhe)是(shi)由于(yu)在(zai)頻(pin)率(lv)(lv)變化后，電動(dong)機仍在(zai)同步轉(zhuan)(zhuan)速附近運行，基本保持額(e)定轉(zhuan)(zhuan)差。只是(shi)在(zai)變頻(pin)裝置系統(tong)中(zhong)會產生變流損失(shi)，以及由于(yu)高次諧波的(de)影響，電動(dong)機的(de)損耗增(zeng)加(jia)，從(cong)而效(xiao)率(lv)(lv)有所(suo)下降(jiang)。

　　2、調速(su)范(fan)圍(wei)寬(kuan)(kuan)，一般可(ke)達20:1，并在整個調速(su)范(fan)圍(wei)內具有高(gao)的(de)調速(su)的(de)效率。所以變頻調速(su)適用于調速(su)范(fan)圍(wei)寬(kuan)(kuan)，且經常(chang)處于低負荷狀態下運行(xing)的(de)場合。

　　3、機械特性較硬，在(zai)無自動(dong)(dong)控制時(shi)，轉速變化率(lv)在(zai)5%以(yi)下(xia);當采(cai)用自動(dong)(dong)控制時(shi)，能做高精(jing)度運行(xing)，把轉速波動(dong)(dong)率(lv)控制在(zai)0.5%|~1%左右。

　　4、變頻裝(zhuang)置萬一發生故(gu)障，可以退出(chu)運行(xing)，改由電(dian)網直接供電(dian)，泵或風機仍可繼續(xu)保持運轉。

　　5、能兼作啟動(dong)(dong)(dong)(dong)設備(bei)，即通過(guo)變頻電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)將電(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)(dong)機(ji)啟動(dong)(dong)(dong)(dong)到某一(yi)轉速，再(zai)斷(duan)開變頻電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)，電(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)(dong)機(ji)可直接(jie)接(jie)到工頻電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)使泵或風機(ji)加(jia)速到全速。在變頻電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)向工頻電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)切(qie)換時，一(yi)般有400%~500%的(de)沖擊電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)產生，電(dian)(dian)(dian)(dian)(dian)(dian)網電(dian)(dian)(dian)(dian)(dian)(dian)壓瞬時下(xia)降，電(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)(dong)機(ji)受到機(ji)械沖擊。為(wei)了避免這(zhe)種現象的(de)產生，可在電(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)(dong)機(ji)和工頻電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)之間(jian)并(bing)聯一(yi)個啟動(dong)(dong)(dong)(dong)電(dian)(dian)(dian)(dian)(dian)(dian)抗器，以(yi)便在啟動(dong)(dong)(dong)(dong)時y制沖擊電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)的(de)產生。若原動(dong)(dong)(dong)(dong)機(ji)為(wei)同步電(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)(dong)機(ji)，則(ze)需(xu)進行“同步切(qie)換”。

　　變頻調速的缺點

　　1、從(cong)目前看，變頻器的(de)初投資太(tai)高，是應用(yong)于(yu)泵或風機調速節能中的(de)主要障礙(ai)。但隨著電子技術的(de)發展，產品成本逐步(bu)提高，其(qi)應用(yong)前景(jing)日益廣闊。

　　2、因變(bian)頻器輸出的電(dian)(dian)(dian)流或電(dian)(dian)(dian)壓的波形(xing)為非正弦波而產生的高次諧波，對電(dian)(dian)(dian)動(dong)機及(ji)電(dian)(dian)(dian)源會產生種(zhong)種(zhong)不良影(ying)響。若采用(yong)PWM型(xing)變(bian)頻器或采用(yong)多重(zhong)化技術的電(dian)(dian)(dian)流型(xing)變(bian)頻器，則這個問題可以得到(dao)大大的g善。