The Application Of The Frequency Changer And PLC In The Multiple-speed Control Of The Conveyer Belt

With the rapid development of industrial automation, production line has been applied to different sorts of manufacturing industries and enterprises. The materials on the production line should be stopped reliably and quickly at the designated location during the processing, which requires a variety of changes of speed on the conveyor belt. The traditional adjustable speed motors have the disadvantages of large bulk, single speed, high prices, narrow scopes and so on. The application of PLC and frequency changer can solve these problems efficiently. PLC control system is suitable for all kinds of common motors. Centered on application and based on computer technology, it meets motors'requirements of speed with high quality supported by specific equipment. Frequency changer, with a variety of arithmetic and logical operations, intelligent control functions, high precision output frequency, can easily change the motor speed. It also has the advantages of high precision, good stability, high reliability, storage capacity and flexibility.In this background, this paper designs the multiple-speed control of the conveyer belt by combining the frequency changer and PLC. This paper firstly introduces the principle of induction motor speed control, speed control methods and the characteristics of the inverter and the PLC, analyzes RS-485 communications in detail, makes an introduction about the choice of hardware, and then gives a full description about the key technologies of the system. Finally it programs the PLC control and realizes the multiple-speed control of the conveyer belt by combining the frequency changer and PLC.