外文翻譯--皮帶傳送系統(tǒng)及其牽引系統(tǒng)-全文預(yù)覽
【正文】 ositive bus voltage)when the switches S1u and S2u are closed， whereas it is in state N (negative bus voltage) when the switches S3u and S4u are closed。 In parison to a twolevel 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。 This kind of inverter can realize a whole range with a voltage rating from 2． 3 kV to 4． 1 6 kV Series connection of HVIGBT modules is used in the 3． 3 kV and 4． 1 6 kV devices。 Scoop control couplings are applied on conveyors requiring single or multiple drives from 150 kW to 750 kW。 When the scoop tube is fully extended into the reservoir, the coupling is 100 percent filled。 The drive system cost is medium to high, depending upon size specified。 To control the starting torque of a singledrive conveyor system， the AC motor current must be monitored to provide feedback to the solenoid control valve。 The coupling’s impellers are mounted on the AC motor and the runners on the driven reducer highspeed shaft。 Fixedfill fluid couplings are the most monly used softstart devices for conveyors with simpler belt profiles and limited convex/concave sections。the output speed is less than the input speed。 Hydraulic fluid is pumped from the driven impeller to the driving runner, producing torque at the driven shaft。 but it is a reliable, costeffective drive in applications in which torque,load sharing and variable speed are primary considerations。 Wherein the motor’s rotating armature is connected externally。However, the control systems for these can be highly plex， because they are based on puter control of the resistance switching。 For conveyor starting， resistance is placed in series with the rotor for low initial torque。 Motors with higher torque and pull—up 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。 This can be achieved through reducedvoltage starters by employing a silicon controlled rectifier(SCR)。 The maintenancefree starting system is simple， lowcost and very reliable。 1 Analysis on conveyor drive technologies 1． 1 Direct drives Fullvoltage starters 。 An efficient drive system should be able to provide smooth， soft starts while maintaining belt tensions within the specified safe limits。 本科畢業(yè)設(shè)計 外文文獻(xiàn) 及 譯文 文獻(xiàn)、資料題目： Belt conveying systems and driving system 文獻(xiàn)、資料來源： 期刊 文獻(xiàn)、資料發(fā)表（出版）日期： 院 （部）： 機(jī)電 工程學(xué)院 專 業(yè)： 機(jī)械電子 班 級： 姓 名： 學(xué) 號： 指導(dǎo)教師： 翻譯日期： 山東建筑大學(xué)畢業(yè)設(shè)計外文文獻(xiàn)及譯文 1 外文 文獻(xiàn) ： Belt conveying systems and driving system Among the methods of material conveying employed， belt conveyors play a very important part in the reliable carrying of material over long distances at petitive cost。 The ability to control drive acceleration torque is critical to belt conveyors’ performance。 Costeffective and performancedriven conveyor drive systems covering a wide range of power are available for customers’ choices。 With direct fullvoltage starters， no control is provided for various conveyor loads and depending on the ratio between f
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