1. Principle of constant tension control

The essence of constant tension control in the process of winding and unwinding is to know the change of winding diameter in 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 machine needs to change with the change of winding diameter. For V series frequency converter, because it can do torque control, so it can complete the control of winding constant tension. V series inverter provides three analog input ports, AUI, AVI, ACI. The three analog inputs can be defined as a variety of functions, so one can be selected as a torque given and the other as a speed limit. 0~ 10V corresponds to the frequency converter output 0~ rated torque of the motor, so that constant tension control can be completed by adjusting the voltage of 0~ 10V. And du Yu stripe machine, the part of the calculation of coil diameter is calculated through the tension controller, of course, with PLC architecture to achieve is no problem. That is to say, 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 size of the motor output can be calculated. The torque given end of the V series converter can be output through the analog quantity.

2. Calculation of synchronous speed

Because we know that when the frequency converter works at low frequency, the characteristics of the stripe machine ac induction motor are not good, the activation torque is low and the division is linear, so we should try to avoid the winding motor working below 2HZ in the whole process of winding. Therefore, there is a minimum speed limit for the winding motor. For a four-level motor, its 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 polar logarithm,n1 is the synchronous speed)

3. Speed limit operation

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

V = PI * D * n/I = Vmin = 60/9 = 3.14 * 1.2 * 25.12 m/min

Tension control, the slitting machine to speed limit, otherwise there will be flying, so speed limit operation.

4. Tension and torque calculation

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, its rated torque calculation is 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)