The cable industry is now developing towards higher skill levels such as product diversification and production automation. In the online cable profession, the widely used one now is the pay off stand, and the power pay off stand is a device with high skill content among them. The power cable rack generally requires the frequency converter to have PID regulation function, and PID can be controlled in both directions. In current professional use, the Sifang V560 vector frequency converter can complete this control requirement without adding any auxiliary accessories. This article intends to introduce an automatic cable laying system with constant tension control for cable career planning, based on the PID controller that comes with the Sifang V560 frequency converter.
Introduction to the process of automatic pay off rack
As the forefront of various devices, power cable racks are widely used in the cable industry. Generally speaking, there are several requirements for the power cable rack:
When the drawing speed increases, the wire laying speed also increases rapidly with the drawing speed;
When the pulling speed slows down, the wire laying speed also slows down with the pulling speed;
When operating steadily at a certain speed, the swing rod of the pay off rack should be stable;
When loose or broken wires are present, it is required that the pay off reel can automatically rotate.
The above requirements are all fulfilled by the PID function of the frequency converter, and it is required that the frequency converter has a considerable response to speed
Sensitive. In response to the above requirements, the following control system has been planned using the V560 frequency converter.
Control plan
The constant tension synchronous control of paying off is a PID control system that outputs the voltage signal back to the inverter after the orientation change of the tension pendulum in the system. After the automatic calculation of the PID controller, the inverter changes the output frequency and then adjusts the running speed of the paying off motor to maintain the constant tension. In practice, this is a direct tension control method. Since the fine-tuning of PID is based on the practical orientation of the swing rod for calculation, rather than directly performing tension calculation, and the orientation and tension are satisfied with a certain functional relationship, the requirement of constant tension control can also be achieved by controlling the practical orientation of the swing rod
The system adopts open-loop vector form, imitates the feedback signal (010V) of the swing rod direction input AI1, and sets the desired swing rod direction point for stable operation as the PID setpoint. During the operation of the system, the response signal is always compared with the given value. The PID controller automatically calculates based on the difference and adjusts the output frequency of the frequency converter to regulate the speed of the pay off motor, ensuring the stability of the swing rod orientation, and then achieving constant tension control.
This article introduces a constant tension automatic unwinding control system based on the square V560 vector type frequency converter. The scheme is very sensitive to speed response and satisfies the equipment skill indicators in fast speed tracking and loose wire reverse winding. At the same time, it can also limit the forward unwinding speed and reverse winding speed separately, taking into account the requirements for unwinding speed and winding speed protection in case of wire breakage. It has been successfully used in multiple automatic unwinding systems.