A V-F Coordinated Control System for Two Motors without any Tension Sensors

To make the two motors´ velocity-tension coordinated control system in the high-speed production of the web such as plastic film running properly and smoothly, this paper proposes a new V-F coordination control scheme without any tension sensors. In the new control system, the asynchronous motors are both controlled by vector inverters. The master motor is working in the velocity mode, which determines the production rate of the machine. The slave motor is working in torque mode of soft closed-loop tension control, and its maximum velocity is constrained by the velocity of the master motor. A new estimation method for tension variable is also raised in the paper, the system tension is calculated by the velocity signals of the two motors and their ratio parameter, and on this basis, the slave motor is controlled by the tension control system with no need of any tension sensors. The paper introduces the principle of the control system, the soft detection method for tension, the control algorithms, and the technical solution of V-F coordinated controller based on an embedded system. The proposed system is simple, easy to implement, and has been applied to several web productions with good control performance.