Abstract : This paper analyzes the principle, implementation method, and corresponding control algorithm of indirect tension control based on frequency converter slip compensation, and presents the application effect. Keywords : frequency converter; slip compensation; indirect tension control 1. Significance of Tension Control in Electrical Drives of Paper Machines Most paper machines have in-machine sizing and in-machine coating, thus the drying cylinder section of the paper machine is divided into two parts: the pre-drying cylinder before sizing or coating, and the post-drying cylinder after sizing or coating. Generally speaking, after the paper web has passed through pre-drying, the moisture content of the paper is close to that of the finished paper, so that sizing or coating can be carried out smoothly. The shrinkage rate of the paper at this dryness is very small. Once there is a slight deviation in the speed ratio between the last set of cylinders in the pre-drying cylinder and the sizing machine or the coating machine, it will cause a large change in the tension of the paper web, which is very easy to cause paper breakage; similarly, the same problem exists between the post-drying cylinder and the calender. A common method to solve this problem is direct tension control: installing paper web tension sensors on the guide rollers of the last cylinder in the pre-drying section and the last cylinder in the post-drying section to directly control the tension of the sizing and calendering machines. The operation involves manually disengaging the tension control during paper feeding and manually re-engaging it after feeding, using a tension regulator to automatically maintain constant tension. However, installing tension sensors is a significant investment and increases maintenance difficulty. Instead of direct tension control, we use indirect tension control: utilizing the slip compensation of the frequency converter softens the mechanical characteristics of the sizing or calendering machine's drive points, using electrical elasticity to compensate for the paper's elasticity, achieving better results. [b][align=center]For details, please click: Frequency Converter Slip Compensation for Indirect Paper Tension Control[/align][/b]