Tension control solution

In the field of industrial automation, in some ribbon and linear products, it is often necessary to control the tension to meet the production requirements. Tension control refers to the ability to permanently control the tension of the raw materials when they are conveyed on the equipment.

Description

Tension control mechanism can be divided into unwinding mechanism, rewinding mechanism, stretching mechanism, tension adjustment roller control mechanism. According to the control method, it can be divided into open-loop tension torque mode, closed-loop tension torque mode, and closed-loop tension speed mode. The open-loop tension torque mode does not require a tension detection mechanism, and the tension is controlled by adjusting the output torque of the motor. It is suitable for occasions where the accuracy of tension is not required; closed-loop tension torque mode is based on the open-loop tension torque mode The tension feedback mechanism is added to adjust the output torque by PID to achieve precise control of the tension; the closed-loop tension speed mode is based on the tension feedback signal and adjusts the operating frequency to indirectly control the tension, and the tension control accuracy is higher .

1. There is no tension feedback in the open-loop tension torque mode. The inverter achieves the purpose of controlling tension by controlling the output torque. The relationship between the tension F of the wire or strip on the reel, the current winding diameter D and the output torque T of the reel shaft is: T = F × D / 2. Controlling the tension in this way requires high accuracy in the calculation of the coil diameter and torque control. In addition, since there is no tension feedback, the system inertia and friction torque must be compensated to ensure that the tension on the wire or strip is constant. The MV600T has a built-in rich curling radius calculation module, supports multiple curling radius calculation modes, and also integrates inertia compensation and friction compensation functions to support tension control in open-loop tension torque mode. 

2. Closed-loop tension torque mode requires tension detection and feedback. PID torque fine-tuning is added on the basis of open-loop tension torque mode. The fine-tuning amount is obtained by tension setting and tension feedback through PID adjustment. The closed-loop tension torque mode has more feedback than the open-loop tension torque mode, so the system is more robust and has better performance. It is suitable for occasions where precise tension control is required. The MV600T has a fast and accurate process PID adjustment module, vector torque control with excellent accuracy and dynamic response capability, which meets the stringent requirements for tension control in the closed-loop tension torque mode.

3. The closed-loop tension speed mode also requires tension detection and feedback, as well as the linear velocity signal of the material. The frequency converter indirectly controls the tension on the wire or strip by controlling the motor speed. This mode has high requirements on the PID adjustment capability and speed control performance of the inverter. Because the MV600T has a PID control module with good performance and precise speed control capabilities, it can easily respond to this mode of tension control applications and achieve precise control of tension. 

Features

Advantages of MV600T series variable frequency drive in tension control application:

• The excellent vector control performance guarantees the steady-state accuracy and dynamic response of torque and speed control, thereby reducing the fluctuation of tension.

• Rich curling radius calculation module, support curling radius calculation through line speed, direct input curling radius signal through analog port, and curling radius calculation method.

• Support inertia compensation and friction torque compensation, can strengthen the tension control accuracy of torque mode.

• Powerful PID adjustment function, suitable for tension control system with tension feedback, to meet the more stringent tension control accuracy requirements.

• Supports high-speed torque compensation to counteract the effect of system friction with speed changes, making tension constant. 

• Support flexible tension taper setting.