【正文】 l vp torque, can provide better starting torque when bined with the SCR starters, which are available in sizes up to 750 KW. Wound rotor induction motors. Wound rotor induction motors are connected directly to the drive system reducer and are a modified configuration of a standard AC induction motor. By inserting resistance in series with the motor39。它以一種優(yōu)化方式確定每一次開(kāi)關(guān)時(shí)刻。 HVIGBT 模塊串聯(lián)可使用在 3. RV 和 4. 16kV的設(shè)備。此種液力偶合器同樣由三個(gè)標(biāo)準(zhǔn)的液力偶合單元構(gòu)成，即葉輪、渦輪和一個(gè)包含工作環(huán)路的外殼?？刂?DC 驅(qū)動(dòng)技術(shù)一般應(yīng)用 SCR 裝置，它允許連續(xù)的變速操作。為了負(fù)載分配在多個(gè)驅(qū)動(dòng)上，扭矩和速度控制在驅(qū)動(dòng)系統(tǒng)的設(shè)計(jì)中也是很重要的因 素。因此，這種方式只用于低功率，結(jié)構(gòu)簡(jiǎn)單的傳送驅(qū)動(dòng)中。由于循環(huán)流體產(chǎn)生扭矩和速度，在驅(qū)動(dòng)軸和從動(dòng)軸之間不需要任何機(jī)械連接。 VFC裝置為感應(yīng)電機(jī)提供變化的頻率和電壓，產(chǎn)生優(yōu)良的啟動(dòng)轉(zhuǎn)矩和加速度。例如，當(dāng)開(kāi)關(guān) S1u 和S2u 閉合時(shí)， U 相處于狀態(tài) P(正母線電壓 )，反之，當(dāng)開(kāi)關(guān) S3u 和 S4U 閉合時(shí)， U 相處于狀態(tài) n(負(fù)母線電壓 )。圖 3 為測(cè)試結(jié)果波形。 the driving hydraulic turbine known as the runner and a casing that encloses the two power ponents. Hydraulic fluid is pumped from the driven impeller to the driving runner, producing torque at the driven shaft. Because circulating hydraulic fluid produces the torque and speed, no mechanical connection is required between the driving and driver power produced by this coupling is based on the circulated fluid39。 choices[1]. 1 Analysis on conveyor drive technologies 1. 1 Direct drives Fullvoltage starters. With a fullvoltage starter design, the conveyor head shaft is directcoupled to the motor through the gear drive. Direct fullvoltage starters are adequate for relatively lowpower, simple Profile conveyors. With direct fullvoltage starters. no control is provided for various conveyor loads and. depending on the ratio between full and noload power requirements, empty starting 8 times can be three or four times faster than full load. The maintenancefree starting system is simple, lowcost and very reliable. However, they cannot control starting torque and maximum stall torque。其基本原理是三電平 PWM 調(diào)制器使用兩個(gè)參考波認(rèn) Ur1 和 Ur2，但只使用一個(gè)三角波。這種逆變器目前可以實(shí)現(xiàn)從 2. RV到 4. 16kV 全范圍的應(yīng)用。 勺管控制液力偶合器 也稱為調(diào)速型液力偶合器。 直流 (DC)電機(jī) 大多數(shù)傳送驅(qū)動(dòng)使用 DC 并勵(lì)電機(jī)，電機(jī)的電樞在外部連接。一個(gè)高效的驅(qū)動(dòng)系統(tǒng)應(yīng)該能順利的運(yùn)行，同時(shí)保持輸送帶張緊力在指定的安全極限負(fù)荷內(nèi)。 降壓?jiǎn)?dòng) 隨著傳送驅(qū) 動(dòng)功率的增加，在加速期間控制使用的電機(jī)扭矩變得越來(lái)越重要。這種連接產(chǎn)生的動(dòng)力決定于液力偶合器的充液量 ，扭矩正比于輸入速度。VFC 設(shè)備是一個(gè)電力電子控制器，首先把 AC 整流成 DC，然后利用逆變器，再將 DC 轉(zhuǎn)換成頻率、電壓可控的 AC. VFC 驅(qū)動(dòng)采用矢量控制或直接轉(zhuǎn)矩控制 (DTC)技術(shù) ，能根據(jù)不同的負(fù)載采用不同的運(yùn)行速度。在中性點(diǎn)箱位時(shí)，該相在 o 狀態(tài)，這時(shí)根據(jù)相電流極性的正負(fù)，或者是 S2U 導(dǎo)通或者是 S3U 導(dǎo)通。由圖看出，曲線 1 顯示受控帶速，帶速呈 S 形曲線形狀，曲線 3 分別表示電流和扭矩，曲線 4 顯示帶張力。s amount and density and the torque in proportion to input 10 speed. Because the pumping action within the fluid coupling depends on centrifugal forces. the output speed is less than the input speed. Referred to as slip. this normally is between 1% and 3%. Basic hydrokiic couplings are available in configurations from fractional to several thousand KW. Fixedfill fluid couplings. Fixedfill fluid couplings are the most monly used softstart devices for conveyors with simpler belt profiles and limited convex/concave sections. They are relatively simple,lowcost,reliable,maintenance free devices that provide excellent soft starting results to the majority of belt conveyors in use today. Variablefill drain couplings. Drainablefluid couplings work on the same principle as fixedfill couplings. The coupling39。s design. Due to the advances in conveyor drive control technology, at present many more reliable. Costeffective and performance driven conveyor drive systems covering a wide range of power are available for customers39。 PWM調(diào)制器 該調(diào)制器實(shí)際上是把空間矢量調(diào)制概念擴(kuò)展到三電平逆變器。高壓 IGBT(HVIGBT)的出現(xiàn)使得應(yīng)用三電平中性點(diǎn)箱位原理的中高壓逆變器設(shè)計(jì)有了更大的應(yīng)用范圍?？勺兂湟阂毫ε己掀骺墒褂迷谥写蠊β瘦斔拖到y(tǒng)中，功率可達(dá)到數(shù)千千瓦口這種驅(qū)動(dòng)無(wú)論在機(jī)械，或在電氣上都是很復(fù)雜的，其驅(qū)動(dòng)系統(tǒng)成本中等。當(dāng)今，控制系統(tǒng)的大多數(shù)是定制設(shè)計(jì)來(lái)滿足傳送系統(tǒng)的特殊規(guī)格繞線轉(zhuǎn)子電機(jī)適合于需要 400kVV 以上的系統(tǒng)?？刂乞?qū)動(dòng)力和加速度扭矩是輸送機(jī)的關(guān)鍵。由于電機(jī)扭矩是電壓的函數(shù)，電機(jī)電壓必須得到控制，一般用可控硅整流器 (SCR}構(gòu)成的降壓?jiǎn)?dòng)裝置，先施加低電壓拉緊輸送帶，然后線性的增加供電電壓直到全電壓和最大帶速。因在流體偶合中輸出速度小于輸入速度，其間的差值稱為滑差，一般為 1%3%。 VFC 驅(qū)動(dòng)能根據(jù)給定的 S 曲線啟動(dòng)或停車，實(shí)現(xiàn)自動(dòng)跟蹤啟動(dòng)或停車曲線。為了保證中性點(diǎn)電壓平衡，在 o 點(diǎn)被注入的平均電流應(yīng)該是零 。從圖中可以發(fā)現(xiàn)，帶張力的波動(dòng)范圍很小，所有檢測(cè)結(jié)果顯示出帶式輸送機(jī)驅(qū)動(dòng)系統(tǒng)令人滿意的特性。s impellers are mounted on the AC motor and the runners on the driven reducer highspeed shaft. Housing mounted to the drive base encloses the working circuit. The coupling39。 performance. A efficient drive system should be able to provid