Abstract: Traditional tension control schemes typically use a tension controller, connecting a tension sensor to it for tension feedback. The required tension is set on the tension controller as the tension setpoint. The tension controller then performs PID calculations on the setpoint and the feedback tension, finally outputting an analog signal to the frequency converter as the master signal to drive the load. This tension control system places high demands not only on the tension controller but also on the frequency converter, requiring not only a fast response time but also excellent filtering time for the analog signal. Therefore, the control cost is high, and on-site commissioning is inconvenient. This paper proposes a scheme using an Emerson TD3300 frequency converter to replace the tension controller for tension control. Keywords: Tension controller, PID calculation, tension control, dedicated frequency converter. In the post-processing combined machine for polypropylene spunbond nonwoven fabric, the nonwoven fabric is first stretched through a diffusion duct, then formed into a web on a web-laying machine, and then formed for the first time using pre-pressing rollers, followed by a second forming using a hot rolling mill. The second forming hot rolling mill can roll out different patterns according to user requirements to meet market needs. The nonwoven fabric formed in the second stage then passes through several spreading rollers, cooling rollers, tension rollers, etc., and is finally wound up by a winding machine, as shown in Figure (I). The quality of the winding effect often depends on the constant tension between the hot rolling mill and the winding machine. Stable tension control will definitely result in a satisfactory winding effect. [align=center] Figure (I) Schematic diagram of the post-processing machine for polypropylene spunbond nonwoven fabric [/align] In traditional tension control schemes, a tension controller is generally used. The tension sensor is connected to the tension controller as tension feedback; the tension required for the process is set on the tension controller as the tension setpoint; then the tension controller performs PID calculations on the setpoint tension and the feedback tension, and finally outputs an analog signal to the frequency converter as the master signal to drive the load. In this tension control system, not only are the requirements for the tension controller quite high, but the requirements for the frequency converter are also very high. The frequency converter must not only have a fast response time, but also a good filtering time for adjusting the analog signal. Therefore, the control cost is not only high, but it is also very inconvenient to debug on site. Therefore, a scheme is proposed to use the Emerson TD3300 frequency converter to replace the tension controller for tension control. According to the supplier, there are two common and mature options for using the Emerson TD3300 frequency converter for tension control: one is open-loop tension control torque mode; the other is closed-loop tension control speed mode. Open-loop tension control mode does not require tension feedback, has fewer system configurations, but its tension control accuracy is slightly lower, and the tension control effect during acceleration and deceleration is not as good as during steady-speed operation. Closed-loop tension control mode requires tension feedback, but it can maintain constant tension throughout acceleration, deceleration, and steady-speed operation. Therefore, we decided to adopt the closed-loop tension control mode of the TD3300 tension control inverter. When selecting the closed-loop tension control speed mode of the TD3300 inverter, F3.06=1 must be selected in the TD3300 inverter parameters. As is well known, the TD3300 series inverters have three analog input terminals, each with its own independent filtering time, and the signal type (voltage, current, etc.) received by the terminals can be set via function codes. In this scheme, the actual tension signal detected by the tension sensor is connected to a tension display meter. The tension meter can convert the sensor signal into different types of analog signals (0-5V, 0-10V, ±10V, etc.), and then send them to the inverter as tension feedback signals. Its connection form is shown in Figure (II). [align=center] Figure (II) Schematic Diagram of Tension Feedback [/align] Assuming the actual operating frequency of the winding machine is set to F, in actual operation, F = F[sub]1[/sub] + F[sub]PID[/sub], where F[sub]1[/sub] is the synchronization frequency, which in this scheme originates from the analog output of the hot rolling mill frequency converter and is calculated as the synchronization frequency after considering parameters such as the mechanical transmission ratio, front and rear pressure rollers, and the winding drum; F[sub]PID[/sub] is the calculated frequency obtained by the frequency converter after PID calculation. When the TD3300 frequency converter performs PID calculation, two conditions must be ensured: tension feedback and tension setting. The synchronization frequency output from the hot rolling mill frequency converter is connected to the TD3300 analog port AI1, and the analog signal from the tension meter is connected to the TD3300 analog port AI2 as tension feedback. Tension setting can be done in different ways: it can be directly set via panel F8.02, via Profibus digital communication, or manually set via analog potentiometer AI3. Different tension setpoints are set under different process requirements. The actual tension value of the system can be directly displayed on the tension meter after passing through the tension sensor for monitoring by process personnel. The specific connection is shown in Figure (III). [align=center] Figure (III) Schematic diagram of electrical drive system configuration [/align] AI1, AI2, and AI3 all have corresponding function codes for selection, namely F6.00, F6.01, and F6.02, and there are also corresponding function codes for adjusting the filter time, F6.03, F6.04, and F6.05. Synchronization frequency: AI1 can be determined by the FC group parameters. The FC group parameters determine its linear speed type and maximum linear speed. Once calibrated, the hot rolling mill and the winding machine are basically synchronized, laying the foundation for subsequent PID calculations (FC0.00 linear speed input selection, FC0.03 maximum linear speed input, etc.). Tension Feedback: AI2 can use parameter group F7 to determine the selection of the feedback channel (F7.02 for feedback selection); Tension Setting: AI3 can use parameter group F8 to determine whether the setpoint is manually set, panel set, analog potentiometer set, or Profibus digital communication set (F8.00 for winding mode, F8.01 for tension selection, F8.02 for digital tension setting, F8.03 for maximum tension, etc.). For detailed operation instructions, please refer to the TD3300 operation manual. Conclusion: This article summarizes the electrical control in the chemical fiber industry. In the polypropylene spunbond nonwoven fabric post-processing combined machine, the winding machine using the Emerson TD3300 frequency converter features a simple on-site configuration, stable operation, and convenient debugging. The actual winding effect is very ideal, with neat end faces and stable tension. It is precisely based on the tension control characteristics of the TD330 frequency converter, coupled with its comprehensive functions, high reliability, and excellent performance-price ratio, that the user's requirements are met. My mailing address is: Electrical Department, Chemical Fiber Institute, Technology Center, Shaoyang Textile Machinery Co., Ltd., Hunan Province. My email address is: [email protected]. My phone number is: 13787499852.