Scheme background
The cable industry is currently evolving to a higher technological level such as product diversification and production automation. In the cable industry, the most widely used is the pay-off rack, which is a kind of equipment with high technical content. The power-discharge rack generally requires the frequency converter to have PID adjustment function, and the PID can be controlled bidirectionally. In the current industry application, Sifang Electric V560 vector inverter can achieve this control requirement without any auxiliary accessories. This article proposes to combine the PID controller of the four-party electrical V560 inverter and introduces a constant tension control active line-out system designed for the cable industry.
Technology introduction
Power take-off racks are the front end of many types of equipment and have a wide range of applications in the cable industry. In general, the following are the requirements for power takeoff racks:
1. When the picking speed is quickened, the payoff speed can be quickly accelerated along with the pulling speed.
2. When decelerating at the pulling speed, the line speed is also decelerated along with the pulling speed;
3. When stable operation is at a certain speed, the swing bar of the pay-off frame must be stable;
4. When loose wires and breaks occur, it is required that the pay-off reels be automatically reversed.
The above requirements are all completed by the PID function of the inverter, and require the inverter to respond to the speed to be quite sensitive.
Control plan
The constant tension synchronous control of the payoff line is through the position change of the tension pendulum in the system, and the output voltage signal is fed back to the PID control system of the frequency converter. After the PID controller automatically calculates, the frequency changer changes the output frequency to adjust the payoff motor Run speed to maintain constant tension. In fact, this is an indirect tension control method, because the fine tuning of PID is based on the actual position of the pendulum, not the direct tension calculation, but the position and tension also satisfy a certain functional relationship, so the pendulum The actual position control can also achieve the constant tension control requirements.
Control principle
The system adopts the open-loop vector mode, and the analog input AI1 connects with the position feedback signal (0~10V) of the pendulum, and the position point of the desired stable operation of the pendulum is set as the PID given value. During the operation of the system, the feedback signal is always compared with the given value. The PID controller automatically calculates the difference according to the difference, and the output frequency of the inverter is changed to adjust the rotation speed of the payoff motor to ensure the stable position of the pendulum, thereby achieving a constant tension. control. The system block diagram is as follows:
Control effect
Based on the constant tension automatic line control system of the Quartet V560 vector frequency converter, this solution is very sensitive to the speed response. It fully meets the technical specifications of the equipment in both the fast speed tracking and the loose line reversal, and can also separately Forward line speed and reverse line speed are limited respectively, taking into account the demand for line speed and line speed protection at the time of disconnection. Currently, it has been successfully applied to multiple active line-out systems, and the application effect is good.
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