Abstract : This paper proposes a variable tension torque control mode that uses a frequency converter to automatically calculate the roll diameter in real time during winding. The working condition and control principle of the winding drive section in the German-imported NWT production line are introduced; the function blocks and parameter setting methods of the Lenze9326 servo frequency converter are described; finally, the implementation of the variable tension torque control mode that uses a frequency converter to automatically calculate the roll diameter in real time is detailed according to process requirements, and the method for online automatic roll diameter calculation and the signal flow diagram in the frequency converter used for winding are given. Keywords: Inorganic felt, GDC software, variable tension torque control mode 1 Overview This paper studies the winding drive section in the German-imported NWT production line. Its working principle is shown in Figure 1. The production line products, glass fiber felt of different thicknesses (20-130 g/m²) (such as printed circuit board substrates), are continuously fed into the winding section via frequency converter motors FM4-5. The main frequency converter motor FM5-1 then winds the fiber onto the roll 1 where the frequency converter motor FM5-2 is located with a certain tension, while the frequency converter motor FM5-4 drives the roll changing operation. When the felt product wound on FM5-2 reel 1 reaches the preset length, the reel 2 driven by the variable frequency motor FM5-3 changes rolls with reel 1. FM5-4 drives the changing reel to rotate clockwise at low speed, and reel 1 and reel 2 begin to switch positions. When reel 1 reaches the unwinding position, reel 2 reaches the winding working position. At this time, the length counter sends a felt-cutting signal, the cutter cuts the felt, and the new felt head is wound onto reel 2 with adhesive tape attached. Reel 1 stops working, completing one roll change operation. At this time, the wound felt roll can be unloaded. When the felt roll on reel 2 reaches the required length, the length counter sends a roll change signal to perform another roll change operation, the process being the same as above. 2 Control Principle [b][align=center]For details, please click: Variable Tension Torque Control Mode for Automatic Calculation of Reel Diameter by Variable Frequency Drive in Winding Drive[/align][/b]