外文翻譯--帶式輸送機(jī)牽引系統(tǒng)的發(fā)展

1、<p><b>　　外文原文</b></p><p>　　Belt Conveying Systems Development of Driving System</p><p>　　Among the methods of material conveying emploved, belt conveyors play a very imporient p

2、art in the reliable carrying of material over long distances at competitive cost. Conveyor systems have become larger and more complex and drive systems have a l so been going through a process of evolution and will cont

3、inue to do so. Nowadays, bigger belts require more power and have brought the need for larger individual drives as well as multiple drives such as 3 drives of 750 kW for one belt(this is the c</p><p>　　With

4、a full-voltage starter design, the conveyor head shaft is direct-coupled to the motor through the gear drive. Direct 8 full-voltage starters are adequate for relatively low-power, simple- Profile conveyors. With direct f

5、ull-voltage starters. no control is provided for various conveyor loads and. depending on the ratio between full- and no-load power requirements, empty starting times can be three or our times faster than full load. The

6、maintenance-free starting system is simple, low-cost an</p><p>　　Reduced-voltage starters. As conveyor power requirements increase,controlling theapplied motor torque during the acceleration period becomes i

7、ncreasingly important. Because motor torque is a function of voltage, motor voltage must be controlled. This can be achieved through reduced-voltage starters by employing a silicon controlled rectifier (SCR). A common st

8、arting method with SCR reduced-voltage starters is to apply low voltage initially to take up conveyor belt slack. and then to apply a time</p><p>　　Wound rotor induction motors. Wound rotor induction motors

9、are 9 connected directly to the drive system reducer and are a modified onfiguration of a standard AC induction motor. By inserting resistance in series with the motor's rotor windings. the modified motor control Sys

10、tem controls motor torque. For conveyor starting, resistance is placed in series with the rotor for low initial torque. As the conveyor accelerates,the resistance is reduced slowly to maintain a constant acceleration tor

11、que. </p><p>　　DC motor. DC motors. available from a fraction of thousands of KW，are designed to deliver constant torque below base speed and constant KW above base speed to themaximum allowable revolutions

12、per minute (r/min). with the majority of conveyor drives, a .DC shunt wound motor is used. Wherein the motor's rotating armature is connected externally. The most common technology for controlling DC drives is a SCR

13、device. which allows for continual variable-speed operation. The DC drive system is mechanic</p><p>　　1. 2 Hydrokinetic coupling Hydrokinetic couplings, commonly referred to as fluid couplings. are compo

14、sed of three basic elements; the driven impeller, which acts as a centrifugal pump; the driving hydraulic turbine known as the runner and a casing that encloses the two power components. Hydraulic fluid is pumped from th

15、e 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 r</p><p>　　Fixed-fill fluid coupl

16、ings. Fixed-fill fluid couplings are the most commonly usedsoft-start devices for conveyors with simpler belt profiles and limited convex/concave sections. They are relatively simple,low-cost,reliable,maintenance free de

17、vices that provide excellent soft starting results to the majority of belt conveyors in use today. </p><p>　　Variable-fill drain couplings. Drainable-fluid couplings work on the same principle as fixed-f

18、ill couplings. The coupling's 11 impellersare mounted on the AC motor and therunners on the driven reducer high-speed shaft. Housing mounted to the drive base encloses the working circuit. The coupling's rotating

19、 casing contains bleed-off orifices that continually allow fluid to exit the working circuit into a separate hydraulic reservoir. Oil from the reservoir is pumped through a heat exchanger to a </p><p>　　Hydr

20、okinetic scoop control drive. The scoop control fluid coupling consists of the three standard fluid coupling cmponents: a driven impeller, a driving runner and a casing that encloses the working circuit. The casing is fi

21、tted with fixed orifices that bleed a predetermined amount of fluid into a reservoir. When the scoop tube is fully extended into the reservoir, the coupling is 100 percent filled. The scoop tube, extending outside the fl

22、uid coupling, is positioned using an electric actuator t</p><p>　　2. 1 Power section To meet the demands for medium voltage applications. a three-level neutral point clamped inverter realizes the power s

23、ection. In comparison to a two-level inverter. the NPC inverter offers the benefit that three voltage levels can be supplied to the output terminals, so for the same output current quality, only 1/4 of the switching freq

24、uency is necessary. Moreover the voltage ratings of the switches in NPC inverter topology will be reduced to 1/2. and the additional transi</p><p>　　The switching states of a three-level inverter are summari

25、zed in Table 1. U. V and W denote each of the three phases respectively; P N and 0 are the do bus points. The phase U, for example, is in state P (positive bus voltage)when the switches S1uand S2u are closed, whereas it

26、is in state N (negative bus voltage) when the switches S3u and S4u, are closed. At neutral point clamping, the phase is in 0 state when either S2u.or S3u, conducts depending on positive or negative phase current polarity

27、, </p><p>　　2. 2 Line side converter For standard applications. a 12-pulse diode rectifier feeds the divided DC-link capacitor. This topology introduces low harmonics on. the line side. For even higher r

28、equirements a 24-pulse diode rectifier can be used as an input converter. For more advanced applications where regeneration. capability is necessary, an active front. end converter can replace the diode rectifier, using

29、the same structure as the inverter.</p><p>　　2. 3 Inverter control Motor Control. Motor control of induction machinesis realized by using a rotor flux. oriented vector controller. Fig. 2 shows the block

30、diagram of indirect vector controlled drive that incorporates both constant torque and high speed field-weakening regions where the PW M modulator was used. In this figure, the command fluxψ.is generated as function of s

31、peed. The feedback speed is added with the feed 15 forward slip command signalψ,the resulting frequency signal is inte</p><p>　　PWM Modulator. The demanded voltage vector is generated using an elaborate PWM

32、modulator. The modulator extends the concepts of space-vector modulation to the three-level inverter. The operation can be explained by starting from a regularly sampled sine-triangle comparison from two-level inverter.

33、Instead of using one set of reference waveforms and one triangle defining the switching frequency, three-level Modulator uses two sets of reference waveforms Uand U and just one triangle. Thus, each sw</p><p&g

34、t;<b>　　外文資料翻譯譯文</b></p><p>　　帶式輸送機(jī)牽引系統(tǒng)的發(fā)展 在運(yùn)送大量的物料時，帶式輸送機(jī)在長距離的運(yùn)輸中起到了非常重要的競爭作用。輸送系統(tǒng)將會變得更大、更復(fù)雜，而驅(qū)動系統(tǒng)也己經(jīng)歷了一個演變過程，并將繼續(xù)這樣下去。如今，較大的輸送帶和多驅(qū)動系統(tǒng)需要更大的功率，比如3驅(qū)動系統(tǒng)需耍給輸送帶750KW(成莊煤礦輸送機(jī)驅(qū)動系統(tǒng)的要求)?？刂乞?qū)動力和加速度扭矩是輸送機(jī)

35、的關(guān)鍵。一個高效的驅(qū)動系統(tǒng)應(yīng)該能順利的運(yùn)行，同時保持輸送帶張緊力在指定的安全極限負(fù)荷內(nèi)。為了負(fù)載分配在多個驅(qū)動上，扭矩和速度控制在驅(qū)動系統(tǒng)的設(shè)計中也是很重要的因素。由于輸送機(jī)驅(qū)動系統(tǒng)控制技術(shù)的進(jìn)步，目前更多可靠的低成本和高效驅(qū)動的驅(qū)動系統(tǒng)可供顧客選擇。</p><p><b>　　帶式輸送機(jī)驅(qū)動 </b></p><p>　　1.1 帶式輸送機(jī)驅(qū)動方式 &l

36、t;/p><p>　　全電壓啟動 在全電壓啟動設(shè)計中，帶式輸送機(jī)驅(qū)動軸通過齒輪傳動直接連接到電機(jī)。直接全壓驅(qū)動沒有為變化的傳送負(fù)載提供任何控制，根據(jù)滿載和空載功率需求的比率，空載啟動時比滿載可能快3-4倍。此種方式的優(yōu)點是:免維護(hù)，啟動系統(tǒng)簡單，低成本，可靠性高。但是，不能控制啟動扭矩和最大停止扭矩。因此，這種方式只用于低功率，結(jié)構(gòu)簡單的傳送驅(qū)動中。 降壓啟動 隨著傳送驅(qū)動功率的增加，在加速期間控制使

37、用的電機(jī)扭矩變得越來越重要。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)成的降壓啟動裝置，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。但是，這種啟動方式不會產(chǎn)生穩(wěn)定的加速度，當(dāng)加速完成時，控制電機(jī)電壓的SCR2 鎖定在全導(dǎo)通，為電機(jī)提供全壓。此種控制方式功率可達(dá)到750kW。 繞線轉(zhuǎn)子感應(yīng)電機(jī) 繞線轉(zhuǎn)子感應(yīng)電機(jī)直接連接到驅(qū)動系統(tǒng)減速機(jī)上，通過在電機(jī)轉(zhuǎn)子繞組中串聯(lián)電阻

38、控制電機(jī)轉(zhuǎn)矩。在傳送裝置啟動時，把電阻串聯(lián)進(jìn)轉(zhuǎn)子產(chǎn)生較低的轉(zhuǎn)矩，當(dāng)傳送帶加速時，電阻逐漸減少保持穩(wěn)定增加轉(zhuǎn)矩。在多驅(qū)動系統(tǒng)中，一個外加的滑差電阻可能將總是串聯(lián)在轉(zhuǎn)</p><p>　　直流(DC)電機(jī) 大多數(shù)傳送驅(qū)動使用DC并勵電機(jī)，電機(jī)的電樞在外部連接?？刂艱C驅(qū)動技術(shù)一般應(yīng)用SCR裝置，它允許連續(xù)的變速操作。DC驅(qū)動系統(tǒng)在機(jī)械上是簡單的，但設(shè)計的電子電路，監(jiān)測和控制整個系統(tǒng)，相比于其他軟啟動系統(tǒng)的選擇是昂

39、貴的，但在轉(zhuǎn)矩、負(fù)載均分和變速為主要考慮的場合，它又是一個可靠的，節(jié)約成本的方式。DC電機(jī)一般使用在功率較大的輸送裝置上，包括需耍輸送帶張力控制的多驅(qū)動系統(tǒng)和需要寬變速范圍的輸送裝置上。</p><p>　　1.2 液力偶合器 </p><p>　　流體動力偶合器通常被稱為液力偶合器，由三個基本單元組成:充當(dāng)離心泵的葉輪，推進(jìn)水壓的渦輪和裝進(jìn)兩個動力部件的外殼。流體從葉輪到渦輪，在從動產(chǎn)生

40、扭矩。由于循環(huán)流體產(chǎn)生扭矩和速度，在驅(qū)動軸和從動軸之間不需要任何機(jī)械連接。這種連接產(chǎn)生的動力決定于液力偶合器的充液量，扭矩正比于輸入速度。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%。傳遞功率可達(dá)幾千千瓦。 固定充液液力偶合器 固定充液液力偶合器是在結(jié)構(gòu)較簡單和僅3 具有有限的彎曲部分的輸送裝置中最常用的軟啟動裝置，其結(jié)構(gòu)相對比較簡單，成本又低對現(xiàn)在使用的大多數(shù)輸送機(jī)能提供優(yōu)良的軟啟動效果。 &

41、lt;/p><p>　　可變充液液力偶合器 也稱為限矩型液力偶合器。偶合器的葉輪裝在AC電機(jī)上，渦輪裝在從動減速器高速軸上，包含操作部件的軸箱安裝在驅(qū)動基座。偶合器的旋轉(zhuǎn)外殼有溢出口，允許液體不斷地從工作腔中流出進(jìn)入一個分離的輔助腔，油從輔助腔通過一個熱交換器泵到控制偶合器充液量的電磁閥。為了控制單機(jī)傳動系統(tǒng)的啟動轉(zhuǎn)矩，必須監(jiān)測AC電機(jī)電流給電磁閥的控制提供反饋?？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

42、可達(dá)到數(shù)千千瓦。這種驅(qū)動無論在機(jī)械，或在電氣上都是很復(fù)雜的，其驅(qū)動系統(tǒng)成本中等。 勺管控制液力偶合器 也稱為調(diào)速型液力偶合器。此種液力偶合器同樣由三個標(biāo)準(zhǔn)的液力偶合單元構(gòu)成，即葉輪、渦輪和一個包含工作環(huán)路的外殼。此種液力偶合器需要在工作腔以外設(shè)置導(dǎo)管(也稱勺管)和導(dǎo)管腔，依靠調(diào)節(jié)裝置改變勺管開度(勺管頂端與旋轉(zhuǎn)外殼間距)人為的改變工作腔的充液量，從而實現(xiàn)對輸出轉(zhuǎn)速的調(diào)節(jié)。這種控制提供了合理的平滑加速度，但其計算機(jī)控制系統(tǒng)很

43、復(fù)雜。勺管控制液力偶合器可以應(yīng)用在單機(jī)或多機(jī)驅(qū)動系統(tǒng)，功率范圍為150kW-750kW。 </p><p>　　1.3 變頻控制(VFC) </p><p>　　變頻控制也是一種直接驅(qū)動方式，它具有非常獨特的高性能。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)良的啟動轉(zhuǎn)矩和加速度。VFC設(shè)備是一個電力電子控制器，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。

44、VFC驅(qū)動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。VFC驅(qū)動能根據(jù)給定的S曲線啟動或停車，實現(xiàn)自動跟蹤啟動或停車曲線。VFC驅(qū)動4為傳送帶啟動提供了優(yōu)良的速度和轉(zhuǎn)矩控制，也能為多機(jī)驅(qū)動系統(tǒng)提供負(fù)載均分。VFC控制器可以容易地裝在小功率輸送機(jī)驅(qū)動上。過去在中高電壓使用時，VFC設(shè)備的結(jié)構(gòu)由于受電力半導(dǎo)體器件的電壓額定值限制而變得很復(fù)雜，中高電壓的變速傳動常常使用低壓逆變器，然后在輸出端使用升壓變壓器，

45、或使用多個低壓逆變器串聯(lián)來解決。與簡單的器件串聯(lián)連接的兩電平逆變器系統(tǒng)比較，由于串聯(lián)器件之間容易均壓以及輸出端可以有更好的諧波特性，三電平電壓型PWI\逆變器系統(tǒng)在數(shù)兆瓦工業(yè)傳動中近年來獲得了越來越多的應(yīng)用。由三臺750kW/ 2.3kv的這種逆變器構(gòu)成的VFC系統(tǒng)已經(jīng)成功安裝在成莊煤礦長2.71m二的帶式輸送機(jī)驅(qū)動系統(tǒng)中。 </p><p><b>　　使用IGBT</b></p&g

46、t;<p>　　IGBT的中性點箱位三電平逆變器 由于串聯(lián)器件電壓均分容易，器件每次開關(guān)的dv/dt低以及輸出端出色的諧波品質(zhì)，三電平電壓型逆變器在大功率傳動應(yīng)用中變得越來越流行。高壓IGBT(HV-IGBT)的出現(xiàn)使得應(yīng)用三電平中性點箱位原理的中高壓逆變器設(shè)計有了更大的應(yīng)用范圍。這種逆變器目前可以實現(xiàn)從2.3kV到4.16kV全范圍的應(yīng)用。HV-IGBT模塊串聯(lián)可使用在3.3kV和4.16kV的設(shè)備。2.3kV逆

47、變器每個開關(guān)只需要一個HV-IGBT[2,3]。 </p><p>　　2.1 主功率逆變電路 主功率逆變電路用三電平中點箱位電壓型逆變器實現(xiàn)，可以滿足中高壓交流傳動應(yīng)用的需要。與兩電平電壓型逆變器相比，三電平中點箱位電壓型逆變器提供三個電壓級別給輸出端，對于同樣的輸出電流品質(zhì)，開關(guān)頻率可降低到原來的1/4，開關(guān)器件的電壓額定值可減小到原來的1/2，附加到電機(jī)上的額外的瞬態(tài)電壓應(yīng)力也可能減少到原來的1/2

48、。三電平中點箱位電壓型逆變器的開關(guān)狀態(tài)可歸納于表1，U，V和W5分別表示三相，P，N和G是直流母線上的三個點。例如，當(dāng)開關(guān)S1u和2u閉合時，U相處于狀態(tài)P(正母線電壓)，反之，當(dāng)開關(guān)S3u和S4U閉合時，U相處于狀態(tài)n(負(fù)母線電壓)。在中性點箱位時，該相在o狀態(tài)，這時根據(jù)相電流極性的正負(fù)，或者是S2U導(dǎo)通或者是S3U導(dǎo)通。為了保證中性點電壓平衡，在o點被注入的平均電流應(yīng)該是零。</p><p>　　2.2 輸入

49、端變流器 為通常使用12脈沖二極管整流器給直流環(huán)節(jié)電容器充電，在輸入端引入的諧波是很小的。若對輸入諧波有更高的要求，可以使用24脈沖二極管整流器作為輸入變流器。對于需要有再生能力的更高級應(yīng)用，可以用一個有源輸入變流器取代二極管整流器，這時輸入整流器與輸出逆變器為同一結(jié)構(gòu)。 </p><p>　　2.3 逆變器控制 電機(jī)控制感應(yīng)電機(jī)的控制可以使用轉(zhuǎn)子磁場定向矢量控制器實現(xiàn)，通過使用PWM調(diào)制器完成了

50、恒轉(zhuǎn)矩區(qū)和高速弱磁區(qū)的控制。圖2為間接矢量控制框圖圖中指令磁通甲ψr是速度的函數(shù)，反饋速度和前饋滑差控制信號川赫目加。對相加結(jié)果的頻率信號積分，然后產(chǎn)生單位矢量(cosθ e和sinOθe )，最后通過矢量旋轉(zhuǎn)器產(chǎn)生電壓V’角θ控制PWM調(diào)制器。 </p><p>　　PWM調(diào)制器 該調(diào)制器實際上是把空間矢量調(diào)制概念擴(kuò)展到三電平逆變器。其基本原理是三電平PWM調(diào)制器使用兩個參考波Ur1和Ur2，但只使用一個三

51、角波。它以一種優(yōu)化方式確定每一次開關(guān)時刻。產(chǎn)生的諧波盡可能的小，使用盡可能低的開關(guān)頻率以最小化開關(guān)損耗；可將零序成分加到每一個參考波里以便最大化基波電壓。作為一個附加的自由度，參考波與三角波的相對位置可改變，這可以用于直流環(huán)節(jié)6中點的電流平衡。</p><p><b>　　3 測試結(jié)果</b></p><p>　　三個750kW/2.3KV三電平逆變器在成莊煤礦2.

52、7km.長帶式輸送機(jī)驅(qū)動系統(tǒng)成功安裝之后，對整個變頻傳動系統(tǒng)(VFC)的性能進(jìn)行了測試，測試結(jié)果顯示出使用VFC控制系統(tǒng)的帶式輸送機(jī)的優(yōu)良特性。圖3為測試結(jié)果波形。由圖看出，曲線1顯示受控帶速，帶速呈S形曲線形狀，曲線2、3分別表示電流和扭矩，曲線4顯示帶張力。從圖中可以發(fā)現(xiàn)，帶張力的波動范圍很小，所有檢測結(jié)果顯示出帶式輸送機(jī)驅(qū)動系統(tǒng)令人滿意的特性。 </p><p><b>　　4 結(jié)論 &l

53、t;/b></p><p>　　近年來輸送機(jī)驅(qū)動控制技術(shù)的進(jìn)步已更為可靠，符合低成本效益和高效驅(qū)動的驅(qū)動系統(tǒng)為用戶提供了選擇。在這些選擇中，可變頻率控制(VFC)的方法顯現(xiàn)出在將來長距離輸送中帶式輸送機(jī)扮演了重要的角色。使用高壓GBT的中點嵌位三電平逆變器本身可以提供電機(jī)終端所需的供電中高壓，使變頻控制的應(yīng)用更為簡單。通過成莊煤礦2. 7km長帶式輸送機(jī)中采用的中點嵌位三電平逆變器變頻調(diào)速(VFC)控制系統(tǒng)