【導讀】電氣工程及其自動化專業(yè)畢業(yè)論文--基于PLC的皮帶集。煤礦對保證礦井正常生產起著非常重要的作SIEMENS的S7-300系列。參數(shù)檢測及故障保護裝置8. 32集控系統(tǒng)PLC的設計21. 普通膠帶機鋼繩芯膠帶輸送機鋼繩牽引膠帶輸送機等均屬于此類運輸設備往返。此它內部的基本運輸單元就是單臺膠帶機膠帶輸送機是選煤廣的主要運輸設備。因每個司機的思想素質和技術素質不等常有以外事故發(fā)生影響生產的正常進行。機構由一名司機來完成操作這不但節(jié)省了大量的司機人員也為及時發(fā)現(xiàn)故障縮。多臺膠帶輸送機給煤機煤倉等構成協(xié)調配合完成長距離運輸任務為保證運輸系。統(tǒng)到多臺的集中控制系統(tǒng)有價格相對較貴的PLC構成的系統(tǒng)和低廉的單片機應。皮帶機的綜合自動化控制是整個礦井實現(xiàn)自動控制的重要組成部分目前對。1在安全保護方面為提高膠帶輸送機運行的可靠性安全性減少故障提高效。率多種檢測方法已應用于電動機液力偶合器減速器和膠帶運行系統(tǒng)故障檢測但。2故障檢測系統(tǒng)誤報率高誤報將造成膠帶輸送機不應有的停機使

　　

【正文】 trol system for the induction motor based on programmable logic controller PLC technology is described Also the implementation of the hardware and software for speed control and protection with the results obtained from tests on induction motor performance is provided The PLC correlates the operational parameters to the speed requested by the user and monitors the system during normal operation and under trip conditions Tests of the induction motor system driven by inverter and controlled by PLC prove a higher accuracy in speed regulation as pared to a conventional V f control system The efficiency of PLC control is increased at high speeds up to 95 of the synchronous speed Thus PLC proves themselves as a very versatile and effective tool in industrial control of electric drives Index TermsComputercontrolled systems puterized monitoring electric drives induction motors motion control programmable logic controllers PLCs variablefrequency drives voltage control I INTRODUCTION Since technology for motion control of electric drives became available the use of programmable logic controllers PLCs with power electronics in electric machines applications has been introduced in the manufacturing automation [1] [2]This use offers advantages such as lower voltage drop when turned on and the ability to control motors and other equipment with a virtually unity power factor [3] Many factories use PLCs in automation processes to diminish production cost and to increase quality and reliability [4]– [9] Other applications include machine tools with improved precision puterized numerical control CNC due to the use of PLCs [10]To obtain accurate industrial electric drive systems it is necessary to use PLCs interfaced with power converters personal puters and other electric equipment [11]– [13] Nevertheless this makes the equipment more sophisticated plex and expensive [14] [15] Few papers were published concerning dc machines controlled by PLCs They report both the implementation of the fuzzy method for speed control of a dc motenerator set using a PLC to change the armature voltage [16] and the incorporation of an adaptive controller based on the selftuning regulator technology into an existing industrial PLC [17] Also other types of machines were interfaced with PLCs Thereby an industrial PLC was used for controlling stepper motors in a fiveaxis rotor position direction and speed reducing the number of circuit ponents lowering the cost and enhancing reliability [18] For switched reluctance motors as a possible alternative to adjustable speed ac and dc drives a single chip logic controller for controlling torque and speed uses a PLC to implement the digital logic coupled with a power controller [19] Other reported application concerns a linear induction motor for passenger elevators with a PLC achieving the control of the drive system and the data acquisition [20]To monitor power quality and identify the disturbances that disrupt production of an electric plant two PLCs were used to determine the sensitivity of the equipment [21] Only few papers were published in the field of induction motors with PLCs A power factor controller for a threephase induction motor utilizes PLC to improve the power factor and to keep its voltage to frequency ratio constant under the whole control conditions [3] The vector control integrated circuit uses a plex programmable logic device CPLD and integer arithmetic for the voltage or current regulation of threephase pulsewidth modulation PWM inverters [22] Many applications of induction motors require besides the motor control functionality the handling of several specific analog and digital IO signals home signals trip signalsOn off reverse mands In such cases a control unit involving a PLC must be added to the system structure This paper presents a PLCbased monitoring and control system for a threephase induction motor It describes the design and implementation of the configured hardware and software The test results obtained on induction motor performance show improved efficiency and increased accuracy in variableload constantspeedcontrolled operation Thus the PLC correlates and controls the operational parameters to the speed set point requested by the user and monitors the induction motor system during normal operation and under trip conditions II PLC AS SYSTEM CONTROLLER A PLC is a microprocessorbased control system designed for automation processes in industrial environments It uses a programmable memory for the internal storage of userorientated instructions for implementing specific functions such as arithmetic counting logic sequencing and timing [23] [24]A PLC can be programmed to sense activate and control industrial equipment and therefore incorporates a number of IO points which allow electrical signals to be interfaced Input devices and output devices of the are connected to the PLC and the control program is entered into the PLC memory In our application it controls through analog and digital inputs and outputs the varying loadconstant speed operation of an induction motor Also the PLC continuously monitors the inputs and activates the outputs according to the control program This PLC system is of modular type posed of specific hardware building blocks modules which plug directly into a proprietary bus a central processor unit CPU a power supply unit inputoutput modules IO and a program terminal Such a modular approach has the advantage that the initial configuration can be expanded for other future applications such as multimachine systems or puter linking III CONTROL SYSTEM OF INDUCTION MOTOR In Fig 2 the block diagram of the experimental system is illustrated The following configurations can be obtained from this setup a A closedloop control system for