1、完整版外文翻译基于PLC异步电动机运行监控系统设计与实施毕业论文Design and Implementation of PLC-Based Monitoring Control System for Induction Motor ZHU Shao-ying，XU Yu，He Zheng-wen Xi an Jiaotong University，Xi an 710049，P.R.ChinaAbstract：The implementation of a monitoring and control system for the induction motor based on progra
2、mmable logic controller (PLC) technology is described. Also, the implementation of the 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
3、 under trip conditions. Tests of the induction motor system driven by inverter and controlled by PLC prove a speed regulation as compared to a conventional control system. The efficiency of PLC control is increased at industrial control of electric drives.Keywords：Computer-controlled systems, comput
4、erized monitoring, electric drives, induction motors, motion control, programmable logic controllers (PLCs), variable-frequency drives, voltage control.I. INTRODUCTIONSince technology for motion control of electric drives became available, the use of programmable logic controllers (PLCs) with power
5、electronics in electric machines applications 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 proce
6、sses to diminish production cost and to increase quality and reliability 49. Other applications include machine tools with improved precision computerized numerical control (CNC) due to the use of PLCs 10. To obtain accurate industrial electric drive systems, it is necessary to use PLCs interfaced w
7、ith power converters, personal computers, and other electric equipment 1113. Nevertheless, this makes the equipment more sophisticated, complex, 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
8、 control of a dc motorgenerator set using a PLC to change the armature voltage 16, and the incorporation of an adaptive controller based on the self-tuning regulator technology into an existing industrial PLC 17. Also, other types of machines were interfaced with PLCs. Thereby, an industrial PLC was
9、 used for controlling stepper motors in a five-axis rotor position, direction and speed, reducing the number of circuit components, 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 cont
10、roller 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 powe
11、r quality and identify the disturbances that disrupt production of an electric plant, two PLCs were used to determine the sensitivity of the equipment 21. II. PLC AS SYSTEM CONTROLLERA PLC is a microprocessor-based control system, designed for automation processes in industrial environments. It uses
12、 a programmable memory for the internal storage of user-orientated 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 o
13、f IO points, which allow electrical signals to be interfaced. Input devices and output devices of the process are connected to the PLC and the control program is entered into the PLC memory (Fig. 1).Fig. 1. Control action of a PLC. III. CONTROL SYSTEM OF INDUCTION MOTORIn Fig. 2, the block diagram o
14、f the experimental system is illustrated. The following configurations can be obtained from this setup.a) A closed-loop control system for constant speed operation, configured with speed feedback and load current feedback. The induction motor drives a variable load, is fed by an inverter, and the PL
15、C controls the inverter Vf output.b) An open-loop control system for variable speed operation. The induction motor drives a variable load and is fed by an inverter in constant Vf control mode. c) The standard variable speed operation. The induction motor drives a variable load and is fed by a consta
16、nt voltage-constant frequency standard three-phase supplyThe open-loop configuration b) can be obtained from the closed-loop configuration a) by removing the speed and load feedback. On the other c) results if the entire control system is bypassed. IV. HARDWARE DESCRIPTIONThe control system is imple
17、mented and tested for a wound rotor induction motor, in Table I. The induction motor drives a dc generator, which supplies a variable R load. The three-phase power supply is connected to a three-phase main switch and then to a three-phase thermal overload relay, which provides protection against cur
18、- rent overloads. The relay output is connected to the rectifier, which rectifies the three-phase voltage and gives a dc input to the insulated gate bipolar transistor (IGBT) inverter. Its technical specifications 25 are summarized in Table II. The IGBT inverter converts the dc voltage input to thre
19、e-phase voltage output, which is supplied to the stator of the induction motor. On the other a PLC modular system 5, 2628. The PLC architecture refers to its internal are shown in Tables III and IV.A speed sensor is used for the speed feedback, a current sensor is used for the load current feedback,
20、 and a second current sensor is connected to the stator circuits 32. Thus, the two feedback loops of the closed-loop system are setup by using the load current sensor, the speed sensor, and the AIM. V. RESULTSThe system was tested during operation with varying loads including tests on induction moto
21、r speed control performance and tests for trip situations. The PLC monitors the motor operation and correlates the parameters according to the software.At the beginning, for reference purposes, the performance of induction motor supplied from a standard 380 V, 50-Hz network was measured. Then, the e
22、xperimental control system was operated between no load and full load (1.0 N m) in the two different modes described in Section III:a) induction motor fed by the inverter and with PLC control;b) induction motor fed by the inverter.The range of load torque and of speed corresponds to the design of th
23、e PLC the previous sections.The speed versus torque characteristics were studied in the range 5001500 rmin and is illustrated in Fig. 7. The results show that configuration b) operates with varying speed-varying load torque characteristics for different speed setpoints. Configuration a) operates wit
24、h constant-speed-varying load torque characteristics in the speed range 01400 rmin and 0100% loads. However, in the range of speeds 1400 rmin and loads 70%, the system operates with varying-speed-varying-load and the constant speed was not possible to be kept. Thus, for 1400 rmin both con-figuration
25、s a) and b) 93% of the synchronous.Fig.6. Flowchart of cutoffrestart motor software.The efficiency for different values of was also studied. In Fig. 8, the efficiency is shown normalized, using as base value or 1 p.u. the efficiency of the induction motor supplied from the standard network. As depic
26、ted in Fig. 8, the results show that configuration a) in all cases configuration b). Also, at operation with loads 70%, the normalized efficiency is 1, meaning that the obtained efficiency with PLC control is the efficiency of induction motor operated from the standard 380-V, 50-Hz network without t
27、he control of PLC and without the inverter. According to this figure, the efficiency of PLC-controlled system is increased up to 1012% compared to the standard motor operation.From a theoretical point of view, if we neglect magnetizing current, an approximate value for the efficiency iswhere s is th
28、e slip and are the stator and rotor winding resistances, respectively. As can be seen from Fig. 7, the PLC-controlled system a) works with very low slip values, almost zero. In all speed and load torque conditions, the configuration a) configuration b), thus the be justified and especially at increa
29、se in magnetizing current resulting in increased losses.This system presents a similar dynamic response as the closed-loop system with Vf speed control. Its transient performance is limited due to oscillations on torque 32 and this behavior restricts the application of this system to processes that
30、only require slow speed variation.VII. CONCLUSIONSuccessful experimental results were obtained from the previously described scheme indicating that the PLC can be used in automated systems with an induction motor. The monitoring control system of the induction motor driven by inverter and controlled
31、 by PLC proves its speed regulation at constant-speed-variable-load operation.The effectiveness of the PLC-based control software is satisfactory up to 96% of the synchronous speed. The obtained efficiency by using PLC control is increased as compared to the open-loop configuration of the induction
32、motor fed by an inverter. Specifically, at of the induction motor supplied from a standard network.Despite the simplicity of the speed control method used, this system presents: constant speed for changes in load torque; full torque available over a wider speed range; very good accuracy in closed-loop speed control scheme; .Thus, the PLC proved to be a versatile and efficient control tool in industrial electric drives applications.References1 Bashore D, Oliaro G, Roney P, et al. Fusion Engineering and Design, 1999, 43:2392 zuru Yon
