【正文】 2. 7 km long belt conveyor drives in Chengzhuang Mine indicates that the performance of NPC threelevel inverter using HVTGBTs together with the control strategy of rotor fieldoriented vector control for induction motor drive is excellent for belt conveyor driving system. 。s 11 impellersare mounted on the AC motor and therunners on the driven reducer highspeed shaft. Housing mounted to the drive base encloses the working circuit. The coupling39。 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。s rotating armature is connected externally. The most mon technology for controlling DC drives is a SCR device. which allows for continual variablespeed operation. The DC drive system is mechanically simple, but can include plex customdesigned electronics to monitor and control the plete system. this system option is expensive in parison to othersoftstart systems. but it is a reliable, costeffective drive in applications in which torque,load sharing and variable speed are primary considerations. DC motors generally are used with higherpower conveyors, 10 including plex profile conveyors with multipledrive systems, booster tripper systems needing belt tension control and conveyors requiring a wide variablespeed range. 1. 2 Hydrokiic coupling Hydrokiic couplings, monly referred to as fluid couplings. are posed of three basic elements。s rotor windings. the modified motor control System 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 torque. On multipledrive systems. an external slip resistor may be left in series with the rotor windings to aid in load sharing .the motor systems have a relatively simple a ,the control systems for these can be highly plex, because they are based on puter control of the resistance switching. Today, the majority of control systems are custom designed to meet a conveyor system39。 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 8 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 times can be three or our 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。 performance. A efficient drive system should be able to provide smooth, soft starts while maintaining belt tensions within the specified safe limits. For load sharing on multiple drives. torque and speed control are also considerations in the drive system39。通過成莊煤礦 2. 7km 長帶式輸送機(jī)中采用的中點(diǎn)嵌位三電平逆變器變頻調(diào)速 (VFC)控制系統(tǒng)的測試結(jié)果表明，采用 BVIGBT 的中點(diǎn)嵌位三電平逆變器以及使用轉(zhuǎn)子磁場矢量控制策略的感應(yīng)電機(jī)變頻傳動，使帶式輸送機(jī)驅(qū)動系統(tǒng)具有非常優(yōu)秀的性能，顯示出良好的應(yīng)用前景。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。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。圖 3 為測試結(jié)果波形。作為一個(gè)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(diǎn)的電流平衡。它以一種優(yōu)化方式確定每一次開關(guān)時(shí)刻。 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。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。對于需要有再生能力的更高級應(yīng)用，可以用一個(gè)有源輸入變流器取代二極管整流器，這時(shí)輸入整流器與輸出逆變器為同一結(jié)構(gòu)。 輸入端變流器 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。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。三電平中點(diǎn)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(gè)點(diǎn)。 主功率逆變電路 主功率逆變電路用三電平中點(diǎn)箱位電壓型逆變器實(shí)現(xiàn)，可以滿足中高壓交流傳動應(yīng)用的需要。HVIGBT 模塊串聯(lián)可使用在 和 。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。由三臺 750kW/ 的這種逆變器構(gòu)成的 VFC 系統(tǒng)已經(jīng)