Abstract: This paper discusses and analyzes the causes of tension generation in the unwinding roll of a rewinder, establishes a dynamic torque balance equation for the unwinding roll, and calculates the roll diameter and armature current setting based on the changes in roll diameter and linear speed. It also performs current compensation during the dynamic process to keep the paper web tension constant. Keywords: rewinder; web tension; scroll diameter calculation; dynamic compensation Abstract: The paper analyzes the procreant cause of the web tension and sets up the dynamic torque equation of the unloading scroll according to the research of the rewinder's scroll tension control. With the change of scroll diameter and velocity, the timing device sets the scroll diameter calculation and armature current calculation by configuration, and compensates the current for the dynamic process. By this way, we can keep the web tension constant. Key words: rewinder; web tension; scroll diameter calculation; dynamic compensation; 1 Description of the characteristics of the unloading roller control The double support roller paper-feeding rewinder is mainly composed of three parts: front and rear bottom rollers and unloading roller. The unloading roller is the core of the system control, and its characteristics are as follows [1]: ① Controlling the unwinding tension is a key factor affecting the quality of the entire rewinder's electrical control system. Due to the long paper web travel between the front and rear bottom rolls and the unwinding roll, numerous tension disturbances, and the large and variable moment of inertia of the unwinding roll, controlling the unwinding tension is challenging. Furthermore, the stability of the unwinding tension is closely related to the quality of the finished paper roll. ② The wide variation in the unwinding roll diameter places demands on the motor's speed range. Using a standard motor would require a large capacity due to the wide speed range. Using a special motor with field-weakening speed regulation allows for voltage-based speed regulation below the base speed and field-weakening speed regulation above the base speed. ③ The unwinding roll requires maintaining a constant unwinding tension during operation, making it a constant power load. ④ The unwinding tension can be directly controlled by adjusting the motor's electric torque or generator braking torque. For details, please click: Dynamic Compensation Analysis of Unwinding Roll Tension Control in Rewinders.