Research And Application Of Tension Control Of The Solar EVA Film Production Line Based On CompactLogix PAC

Solar EVA(Ethylene Vinyl Acetate) film is widely used and an important material for solar photovoltaic cell production to encapsulate the solar photovoltaic panels. Good quality EVA encapsulation film can guarantee solar cells with up to 25 years of peak generation performance, and proper tension control will make sure EVA encapsulation film with good shrinking ratio to meet the challenge of solar photovoltaic panel encapsulation. Therefore, tension control plays a great role in the production of solar EVA film. As a web transport system with winder for elastic material such as EVA is characteristic with non-linearity and time-variation due to the wide-range variation of the radius of the winder, this presents great difficulty for EVA film production. This paper is mainly about the research and application of tension control system for EVA film production line. According to the mechanical structure and PAC devices, we give a proper design and commission of the tension control system to satisfy the demand of the plastic manufacture.Firstly, this paper gives a brief introduction of tension control such as how the tension occurred and commonly used control strategies in industrial productions. Based on which kind of feedback device is used, a dancer roller or a tension transducer roller, to close the tension control loop, tension control can be classified into position regulation and tension regulation. Because of the importance of radius calculation for taper tension control, we give some methods for radius calculation.In addition, we give a description of the mechanism structure and the hardware and software of the electrical control system. The whole EVA production line is divided into four parts: the extruder, the casting station, pull roller and the winder station and each part is designed with a proper tension control strategy. Then, the CompactLogix PAC 1768-L43S and PowerFlex 755 driver are introduced, this devices are connected by Ethernet/IP network with HMI and Point IO modules to form the whole control system.Lastly, this paper analyzes and commissions the tension control strategy of each part, a tread diagram for each part is presented. Because of the wide-range variation due to the change of the radius of the winder and the line-speed, regular PID algorithm can't get a good result. A gain changeable PI control algorithm is presented and simulated for close-loop tension control, a better result shows its high performance for this system.