1. Constant tension control principle

For the essence of constant tension control in the process of winding and unwinding, it is necessary to know the change of winding diameter during the operation of the load. Due to the change of winding diameter, in order to maintain the operation of the load, the output torque of the motor of the split machine needs to change with the change of winding diameter. For V series frequency converter, because it can do torque control, it can complete the control of winding constant tension. V series frequency converter provides three analog input ports, AUI, AVI and ACI. These three analog inputs can be defined as multiple functions. Therefore, one can be selected as torque setting and the other as speed limit. 0 ~ 10V corresponds to the frequency converter to output 0 ~ motor rated torque, so the constant tension control can be completed by adjusting the voltage of 0 ~ 10V. And Du Yu Slitter, the part of calculating the coil diameter is calculated through the tension controller. Of course, there is no problem to realize it with PLC architecture. In other words, the tension can be set on the man-machine or text, and the winding diameter can be calculated by PLC, t = f * D / 2, so the torque required to be output by the motor can be calculated, and the analog output can be connected to the torque setting end of V series frequency converter.

2. Synchronous speed calculation

As we know that when the frequency converter works at low frequency, the AC asynchronous motor of the slitter has poor characteristics, low activation torque and partial linearity. Therefore, in the whole process of winding, we should try to avoid the winding motor working below 2Hz. Therefore, the winding motor has a minimum speed limit. For four-stage motor, the synchronous speed is calculated as follows: N1 = 30f1 / P = N1 = 1500r / min = 2Hz / 50Hz = n / 1500 = n = 60rpm / min

(F1 is the rated frequency, P is the number of poles, and N1 is the synchronous speed)

3. Speed limit operation

When the maximum winding diameter is reached, the lowest speed during the whole winding process can be calculated:

V=π*D*n/i=Vmin=3.14*1.2*60/9=25.12m/min

During tension control, the slitter shall limit the speed, otherwise there will be flying, so it shall run at a speed limit.

4. Calculation of tension and torque

If f * D / 2 = t / I (F -- tension, D -- winding diameter, T -- torque, I -- reduction ratio), = f = 2 * t * I / D, for 3.7KW AC motor, the rated torque is calculated as follows: T = 9550 * P / N = t = 24.88n. M, so Fmax = 2 * 24.88 * 9 / 0.6 = 74.64n (T -- rated torque of motor, P -- rated power of motor, n = = rated speed of motor)