負(fù)載轉(zhuǎn)矩TL與轉(zhuǎn)速n無關(guān),，任何轉(zhuǎn)速下TL總保持恒定或基本恒定,。例如傳送帶、攪拌機,，擠壓機等摩擦類負(fù)載以及吊車,、提升機等位能負(fù)載都屬于恒轉(zhuǎn)矩負(fù)載。變頻器拖動恒轉(zhuǎn)矩性質(zhì)的負(fù)載時,，低速下的轉(zhuǎn)矩要足夠大,，并且有足夠的過載能力。如果需要在低速下穩(wěn)速運行,，應(yīng)該考慮標(biāo)準(zhǔn)異步電動機的散熱能力,，避免電動機的溫升過高。

2,、功率負(fù)載

廈門岳航計算機工程有限公司

聯(lián)系人：李素云

企業(yè)QQ：2851195446,，2851195466

手機：18965423501

座機：0592-5165501

機床主軸和軋機、造紙機,、塑料薄膜生產(chǎn)線中的卷取機,、開卷機等要求的轉(zhuǎn)矩，大體與轉(zhuǎn)速成反比,，這就是所謂的恒功率負(fù)載,。負(fù)載的恒功率性質(zhì)應(yīng)該是就一定的速度變化范圍而言的,。當(dāng)速度很低時，受機械強度的限制,，TL 不可能增大,，在低速下轉(zhuǎn)變?yōu)楹戕D(zhuǎn)矩性質(zhì)。負(fù)載的恒功率區(qū)和恒轉(zhuǎn)矩區(qū)對傳動方案的選擇有很大的影響,。電動機在恒磁通調(diào)速時,，*大允許輸出轉(zhuǎn)矩不變，屬于恒轉(zhuǎn)矩調(diào)速;而在弱磁調(diào)速時,，*大允許輸出轉(zhuǎn)矩與速度成反比,，屬于恒功率調(diào)速。如果電動機的恒轉(zhuǎn)矩和恒功率調(diào)速的范圍與負(fù)載的恒轉(zhuǎn)矩和恒功率范圍相一致時,，即所謂“匹配”的情況下,，電動機的容量和變頻器的容量均*小。

3,、平方轉(zhuǎn)距負(fù)載

在各種風(fēng)機,、水泵、油泵中,，隨葉輪的轉(zhuǎn)動，空氣或液體在一定的速度范圍內(nèi)所產(chǎn)生的阻力大致與速度n的2次方成正比,。隨著轉(zhuǎn)速的減小,，轉(zhuǎn)矩按轉(zhuǎn)速的2 次方減小。這種負(fù)載所需的功率與速度的3 次方成正比,。當(dāng)所需風(fēng)量,、流量減小時，利用變頻器通過調(diào)速的方式來調(diào)節(jié)風(fēng)量,、流量,，可以大幅度地節(jié)約電能。由于高速時所需功率隨轉(zhuǎn)速增長過快,，與速度的三次方成正比,，所以通常不應(yīng)使風(fēng)機、泵類負(fù)載超工頻運行,。

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