How is the looper tension controlled?

The speed and torque of the looper can refer to the relevant calculation formula of the uncoiler, but the difference is that the speed must be divided by the number of steel strips, and the torque must be multiplied by the number of steel strips. In addition, according to the diameter of the winch drum, the loop is constant. There are two methods to compensate the looper torque, one is the closed-loop control of actual measurement, and the other is the comprehensive calculation. Because the steel strip in the loop is long, and the tension of the loop fluctuates greatly, the accurate control mode is closed-loop control, that is, a tension sensor is installed below the steering roller with half the number of loops to calculate the actual tension of the loop, and the difference value is calculated by comparing it with the set value, and the difference value is calculated by the Pl regulator and input into the control system as deviation compensation. The comprehensive calculation algorithm is to add a T400 process board and comprehensively calculate the parameters such as friction additional torque, steel belt weight additional torque and dynamic inertia additional torque. The loop is mostly in reserve state, and the motor does not rotate, but it can still output torque accurately. This is a zero-frequency torque output, which can only be realized under vector control, which is essentially different from the locked-rotor state of inverter-less asynchronous motor.