外文翻譯--皮帶傳送系統(tǒng)及其牽引系統(tǒng)

1、<p><b>　　本科畢業(yè)設(shè)計</b></p><p><b>　　外文文獻及譯文</b></p><p>　　文獻、資料題目：Belt conveying systems and driving system</p><p>　　文獻、資料來源：期刊</p><p>　　文獻、資料發(fā)表

2、（出版）日期：2012.3.2</p><p>　　院 （部）： 機電工程學(xué)院</p><p>　　專 業(yè)： 機械電子</p><p><b>　　班 級： </b></p><p><b>　　姓 名： </b></p><p><b>　　學(xué)

3、 號： </b></p><p><b>　　指導(dǎo)教師： </b></p><p>　　翻譯日期： 2012.4.25</p><p><b>　　外文文獻：</b></p><p>　　Belt conveying systems and driving system <

4、/p><p>　　Among the methods of material conveying employed，belt conveyors play a very important part in the reliable carrying of material over long distances at competitive cost。Conveyor systems have become lar

5、ger and more complex and drive systems have also been going through a process of evolution and will continue to do so。Nowadays，bigger belts require more power and have brought the need for larger individual drives as wel

6、l as multiple drives such as 3 drives of 750 kW for one belt(this is the case f</p><p>　　1 Analysis on conveyor drive technologies</p><p>　　1．1 Direct drives</p><p>　　Full-voltage s

7、tarters。With a full-voltage starter design，the conveyor head shaft is direct-coupled to the motor through the gear drive。Direct full-voltage starters are adequate for relatively low-power, simple-profile conveyors。With d

8、irect full-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 four times faster than full load。

9、The maintenance-free starting system is simple</p><p>　　Reduced-voltage starters。As conveyor power requirements increase，controlling the applied motor torque during the acceleration period becomes increasing

10、ly important。Because motor torque 1second 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 starting me

11、thod with SCR reduced-voltage starters is to apply low voltage initially to take up conveyor belt slack，and then to apply a timed</p><p>　　Wound rotor induction motors。Wound rotor induction motors are connec

12、ted directly to the drive system reducer and are a modified configuration of a standard AC induction motor。By inserting resistance in series with the motor’s rotor windings。the modified motor control system controls moto

13、r 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 torque。On multi</p&g

14、t;<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 the maximum allowable revolutions per minute

15、(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 device，which allows

16、 for continual variable-speed operation。The DC drive system is mechanically</p><p>　　1．2 Hydrokinetic coupling</p><p>　　Hydrokinetic couplings，commonly referred to as fluid couplings，are compose

17、d 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 the dr

18、iven 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 drive</p>&l

19、t;p>　　Fixed-fill fluid couplings。Fixed-fill fluid couplings are the most commonly used soft-start devices for conveyors with simpler belt profiles and limited convex/concave sections。They are relatively simple,low-cos

20、t,reliable,maintenance free devices 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 s

21、ame principle as fixed-fill couplings。The coupling’s impellers are mounted on the AC motor and the runners on the driven reducer high-speed shaft。Housing mounted to the drive base encloses the working circuit。The couplin

22、g’s rotating 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 solenoi</p>

23、;<p>　　Hydrokinetic scoop control drive。The scoop control fluid coupling consists of the three standard fluid coupling components：a driven impeller, a driving runner and a casing that encloses the working circuit。

24、The casing is fitted 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

25、outside the fluid coupling，is positioned using an electric actuator to eng</p><p>　　2 Neutral point clamped(NPC)three-level inverter using IGBTs</p><p>　　Three-level voltage-fed inverters have r

26、ecently become more and more popular for higher power drive applications because of their easy voltage sharing features。lower dv/dt per switching for each of the devices，and superior harmonic quality at the output。The av

27、ailability of HV-IGBTs has led to the design of a new range of medium-high voltage inverter using three-level NPC topology。This kind of inverter can realize a whole range with a voltage rating from 2．3 kV to 4．1 6 kV Ser

28、ies connection of HV</p><p>　　2．1 Power section</p><p>　　To meet the demands for medium voltage applications。a three-level neutral point clamped inverter realizes the power section。In comparison

29、 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 frequency is necessary。Moreo

30、ver the voltage ratings of the switches in NPC inverter topology will be reduced to 1/2。and the additional transient voltage stress on the moto</p><p>　　The switching states of a three-level inverter are sum

31、marized in Table 1．U．V and W denote each of the three phases respectively；P N and O are the dc bus points。The phase U，for example，is in state P(positive bus voltage)when the switches S1u and S2u are closed，whereas it is

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

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

34、For even higher requirements 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 rec

35、tifier, using the same structure as the inverter。</p><p>　　3 Testing results</p><p>　　After Successful installation of three 750 kW /2．3 kV three-level inverters for one 2．7 km long belt conveyo

36、r driving system in Chengzhuang Mine。The performance of the whole VFC system was tested。Fig3 is taken from the test，which shows the excellent characteristic of the belt conveyor driving system with VFC controller。</p&

37、gt;<p>　　Fig．3 includes four curves。The curve 1 shows the belt tension。From the curve it can be find that the fluctuation range of the belt tension is very small。Curve 2 and curve 3 indicate current and torque sep

38、arately。Curve 4 shows the velocity of the controlled belt。The belt velocity have the“s”shape characteristic。All the results of the test show a very satisfied characteristic for belt driving system。</p><p>　　

39、4 Conclusions</p><p>　　Advances in conveyor drive control technology in recent years have resulted in many more reliable。Cost-effective and performance-driven conveyor drive system choices for users。Among th

40、ese choices，the Variable frequency control (VFC) method shows promising use in the future for long distance belt conveyor drives due to its excellent performances。The NPC three-level inverter using high voltage IGBTs mak

41、e the Variable frequency control in medium voltage applications become much more simple because </p><p><b>　　中文譯文：</b></p><p>　　皮帶傳送系統(tǒng)及其牽引系統(tǒng)</p><p>　　在運送大量的物料時，帶式輸送機在長距離

42、的運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)也已經(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)需要給輸送帶750KW (成莊煤礦輸送機驅(qū)動系統(tǒng)的要求)?？刂乞?qū)動力和加速度扭矩是輸送機的關(guān)鍵。一個高效的驅(qū)動系統(tǒng)應(yīng)該能順利的運行,同時保持輸送帶張緊力在指定的安全極限負荷內(nèi)。為了負載分配在多個驅(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。由于輸送機驅(qū)

43、動系統(tǒng)控制技術(shù)的進步,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[1]。</p><p><b>　　1 帶式輸送機驅(qū)動</b></p><p>　　1.1 帶式輸送機驅(qū)動方式</p><p>　　全電壓啟動 在全電壓啟動設(shè)計中，帶式輸送機驅(qū)動軸通過齒輪傳動直接連接到電機。直接全壓驅(qū)動沒有為變化的傳送負載提供任何控制,根據(jù)滿載和

44、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,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。</p><p>　　降壓啟動 隨著傳送驅(qū)動功率的增加,在加速期間控制使用的電機扭矩變得越來越重要。由于電機扭矩是電壓的函數(shù),電機電壓必須得到控制，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

45、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,控制電機電壓的SCR 鎖定在全導(dǎo)通，為電機提供全壓。此種控制方式功率可達到750kW。</p><p>　　繞線轉(zhuǎn)子感應(yīng)電機 繞線轉(zhuǎn)子感應(yīng)電機直接連接到驅(qū)動系統(tǒng)減速機上,通過在電機轉(zhuǎn)子繞組中串聯(lián)電阻控制電機轉(zhuǎn)矩。在傳送裝置啟動時,把電阻串聯(lián)進轉(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

46、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)子繞組回路中以幫助均分負載。該方式的電機系統(tǒng)設(shè)計相對簡單，但控制系統(tǒng)可能很復(fù)雜，因為它們是基于計算機控制的電阻切換。當(dāng)今，控制系統(tǒng)的大多數(shù)是定制設(shè)計來滿足傳送系統(tǒng)的特殊規(guī)格。繞線轉(zhuǎn)子電機適合于需要400kW以上的系統(tǒng)。</p><p>　　直流(DC)電機 大多數(shù)傳送驅(qū)動使用DC 并勵電機，電機的電樞在外部連接?？刂艱C 驅(qū)動技術(shù)一般應(yīng)用SCR裝置，

47、它允許連續(xù)的變速操作。DC 驅(qū)動系統(tǒng)在機械上是簡單的,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)的選擇是昂貴的，但在轉(zhuǎn)矩、負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 電機一般使用在功率較大的輸送裝置上,包括需要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><b>　　1.2 液力偶合器</b></p>&l

48、t;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,推進水壓的渦輪和裝進兩個動力部件的外殼。流體從葉輪到渦輪，在從動軸產(chǎn)生扭矩。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 %。傳遞功率可達幾千千瓦。</p><p>

49、;　　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)輸送機能提供優(yōu)良的軟啟動效果。</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

50、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。為了控制單機傳動系統(tǒng)的啟動轉(zhuǎn)矩,必須監(jiān)測AC 電機電流,給電磁閥的控制提供反饋。可變充液液力偶合器可使用在中大功率輸送系統(tǒng)中，功率可達到數(shù)千千瓦。這種驅(qū)動無論在機械,或在電氣上都是很復(fù)雜的，其驅(qū)動系統(tǒng)成本中等。</p><p>　　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

51、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，但其計算機控制系統(tǒng)很復(fù)雜。勺管控制液力偶合器可以應(yīng)用在單機或多機驅(qū)動系統(tǒng)， 功率范圍為150kW～750kW。</p><p>　　2 使用IGBT的中性點箝位三電平逆變器</p&

52、gt;<p>　　由于串聯(lián)器件電壓均分容易,器件每次開關(guān)的d v/ d t 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)用三電平中性點箝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逆變器每個開關(guān)只需要

53、一個HV-IGBT[2,3]。</p><p>　　2．1 主功率逆變電路</p><p>　　主功率逆變電路用三電平中點箝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，三電平中點箝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 ，附加到電機上的額外的瞬態(tài)電壓應(yīng)力也

54、可能減少到原來的1/ 2 。</p><p>　　三電平中點箝位電壓型逆變器的開關(guān)狀態(tài)可歸納于表1 ，U ，V 和W 分別表示三相， P，N 和O 是直流母線上的三個點。例如，當(dāng)開關(guān)S1U和S2U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 (負母線電壓) 。在中性點箝位時,該相在O 狀態(tài)，這時根據(jù)相電流極性的正負,或者是S2U導(dǎo)通或者是S3U導(dǎo)通。為了保證中性點電

55、壓平衡，在O 點被注入的平均電流應(yīng)該是零。</p><p>　　2.2 輸入端變流器</p><p>　　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>

56、;<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. 7km 長帶式輸送機驅(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

57、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驅(qū)動系統(tǒng)令人滿意的特性。</p><p><b>　　結(jié)論</b></p><p>　　近年來輸送機驅(qū)動控制技術(shù)的進步已更為可靠，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扮演了重要的角色。使用