Research On Precision Yarn Tension Controller

The textile industry is a pillar industry of our national economy since ancient times. With the development of technology, the applications of textile technology is no longer confined to spinning, and it has been widely used in the high-tech area of aerospace, medical, military.In the weaving process, yarn tension is an important parameter that affects the quality of fabrics and processing efficiency, so it must be controlled precisely. With the rapid development of electronic and computer technology, foreign textile equipment has been very intelligent, and yarn tension control technology has been matured. But in China, mechanical textile equipment is still dominated due to weak industrial base, which results in ineffecient fabric forming and reduction of the added value of products. This article is aimed at developing a sophisticated yarn tension controller that can keep the tension constant during weaving process and improve the quality of fabric and processing efficiency.The control mode of yarn tension was studied, then the using of active unwinding tension control structure was determined, and its mathematical model was established, meanwhile an overall program based on the mathematical model was developed: Permanent magnet synchronous motor was selected to be the actuator, and the constant yarn tension control was realized by controlling motor speed. Dual closed-loop of current and speed control strategy were used to ensure the accurate and stable control of yarn tension. Fuzzy PID control algorithm was used in the speed loop, which can improve the adaptability of the system, and field oriented control algorithm and space vector pulse width modulation algorithm were used in the current loop, which can improve the stability of the system.Then the hardware circuit of tension controller was designed based on the mathematical model,including the design of the motor drive circuit and the three-phase inverter circuit. And the detection hardware circuit of current, voltage, tension and speed were also designed to realize the real-time data feeds. The temperature detection and over-current protection hardware circuit were developed which were able to achieve self-protection.The programs of tension controller, including the algorithm programs of field oriented control and space vector pulse width modulation were written by C language. The fuzzy PID algorithm was written by MATLAB fuzzy toolbox. ADC collection, PWM output and LCD display programs based on STM32 firmware library were also completed.Through the research on tension detection and control technology, constant yarn tension control was achieved. The results of debugging and experiments showed that the equipment runs smoothly, controls precisely, and the resolution is up to 0.1g and the error is 1%.