[b]1 Introduction[/b] PVC film forming machinery and equipment have many functions. They are used to process PVC granules, which are heated and melted, then extruded, shaped, laminated, and cooled to form PVC film on a production line. In the past, this type of equipment was mainly imported from abroad. Due to high costs and maintenance expenses, and long maintenance cycles, domestic companies have gradually begun to develop their own equipment, which has seen good market application. The author used a Fuji HMI and PLC for synchronous control, and a frequency converter for precise transmission control. This system can meet the control requirements and accuracy of the relevant equipment, greatly simplifying the traditional control system and improving the reliability of the equipment. Its price is only one-fifth of similar foreign products, creating a new economic growth point for users. [b]2 System Requirements[/b] This system is equipped with 12 frequency converters, divided into four parts: System A, System B, System C, and System D. System A has 1 inverter, System B has 1 inverter, System C has 1 inverter, and System D has 9 inverters. The system's working process consists of four parts, each with manual and automatic modes. Since the first three processes are mainly controlled independently by a single unit, this paper focuses on the full-line control process of multiple units working together in a synchronized manner. 2.1 Full-line control process (1) Manual mode: Each system is debugged separately; (2) Automatic mode (a) System A feeds materials according to process requirements; (b) System B controls the rotation speed according to temperature (the raw material heating is controlled by a Fuji temperature controller); (c) System C adjusts the cooling air volume according to production requirements and the signal from the on-site temperature measuring element; (d) System D: Sets the extrusion speed according to the winding speed; The extrusion roller speed is adjusted proportionally to the winding speed; Each group of extrusion rollers is controlled synchronously according to the speed ratio. 2.2 Technical requirements In order to facilitate on-site personnel monitoring, the main screen is required to display the status of each part of the entire system (as shown in Figure 1) and allow operation of the entire system to start/stop. Meanwhile, the operator can switch to the four sub-screens A, B, C, and D through the main screen to monitor the on/off, current/frequency, linear speed and other parameters of all frequency converters, heaters, temperature controllers and each workstation, and adjust the parameters of all devices according to the process requirements. [b]3 System Design[/b] In view of the system requirements for the synchronous and simultaneous start and stop control of multiple frequency converters, the new generation of Fuji human-machine interface is used to realize system integration. The system electrical diagram is shown in Figure 2. 3.1 Hardware System The system consists of 12 frequency converters, 3 heating temperature controllers, 3 cooling temperature controllers and one human-machine interface connected by MODBUS. The control line saves many control lines of PLC, and only three-core shielded cable is needed to realize full digital control and display monitoring. (1) Frequency converter selection Fuji Electric low noise, high performance, multi-functional constant torque G11 series frequency converter is selected. (a) The inverter can realize dynamic torque vector control and can output 200% torque at a low speed of 0.5Hz to prevent speed changes caused by load fluctuations and affect product quality; (b) Synchronization cards are used to control each group of extrusion rollers to maintain the winding flow; (c) The four groups of extrusion rollers are controlled by speed ratio synchronization to ensure system stability. (2) The human-machine interface is selected from Fuji Electric's new generation ultra-thin human-machine interface (POD) UG530-VH4. This machine has a 21-inch color display screen, a 32-bit RISC CPU, and a communication speed of up to 115200bps; it can be directly connected to any brand of PLC, and can also communicate directly with computers, microcontrollers, etc. It has a built-in printer interface and can be connected to Ethernet; it can be controlled by the host computer in the central control room. 3.2 Software system The system software consists of POD screen system, inverter drive system, temperature acquisition, display control. Because the human-machine interface has powerful programming instructions—macro instructions (similar to PLC programming language)—it can perform some functions of PLC software. At the same time, the communication with the frequency converter is all digital, so the accuracy is high and the speed is fast. [b]4 Conclusion[/b] (1) Due to the high control accuracy and strong overload capacity of the system, the production line speed is increased by 10-15%, and the finished product is improved. (2) The system adopts MODBUS, which is a real-time monitoring system with all-digital communication. The original data acquisition setting line is simplified. In terms of operation, various process controls can be completed by simply flipping the screen. (3) The IS485 bus is adopted, and the signal transmission line between the PLC and the frequency converter is simplified to a three-core wire. (4) The equipment transformation investment is only about 200,000 yuan, which greatly improves labor productivity. [b]References[/b] [1] UG30 Series User Manual [Z]. Fuji Electric. [2] MICREX-SX Series SPH User Manual [Z]. Fuji Electric. [3] MICREX-SX SPH D300WIN [Z]. Fuji Electric. [4] FRENIC 5000 VG7S User Manual [Z]. Fuji Electric. [5] FRENIC 5000 G11S/P11S User Manual [Z]. Fuji Electric. About the Author: Chen Kaihua (1953-) Male, Senior Engineer. Graduated from Shanghai Jiaotong University Branch in 1984 with a major in Electrical Automation. He has long been engaged in the development of light industrial products and the digestion and absorption management of imported technologies. He is currently the head of Shanghai Light Industry Science and Technology Development Center.