The Design Of Servo Control System About Flat Knitting Machine Yarn Constant Tension

There are massive textile industry in China,including many practitioners,meanwhile they have produced significant economic benefit,which is a traditional pillar industry in our country.But our country's textile products are mostly used in the low-end market,high-end market almost completely are dominated by foreign brands.The reason is that the production capacity is very low about China's high-end fabrics.Yarn tension is a very important process parameters of fabric production,whose stability is directly related to the quality of fabric.Tension will increase the rate of broken,tension is too small to cause the bad sides and drop needle.For the above problems,this article designs a constant tension machine to send yarn.Firstly,the domestic and foreign development present situation about the yarn tension control system is presented,then expounds the research significance of this topic.On the basis of the theory about tension control,analyze the main factors which influences the yarn tension.After that,put forward the general design method in which permanent magnet synchronous motor is the actuator,the resistance strain gauge type sensor is tension detection module.The advantages of the scheme is the detection precision and high reliability,and can lower the torque ripple effect on the yarn tension.Secondly,on the basis of the general design method,this paper presents three closed loop servo control method which based on the tension-speed – current.In this article,proportional control is used for the tensile ring,the speed loop and current loop adopt PI controller.In view of the speed loop,fuzzy control is used,which can improve the adaptability of system;Current loop adopts the field-oriented control(FOC)algorithm and pulse width and space voltage vector modulation(SVPWM)algorithm,which can effectively reduce the motor torque ripple and improve the stability of system.Again,on the basis of the overall design,complete the software and hardware design of constant tension send yarn.In the hardware design,mainly complete the power supply of system,motor drive,the design of the detection circuit and the protection circuit.Software design mainly complete the realization of control algorithm about FOC,SVPWM and the fuzzy PID.Finally,using MATLAB to conduct the modeling and simulation about permanent magnet synchronous motor control method,through the simulation analysis,it is concluded that the use of control scheme can satisfy the control demand of yarn tension.On the basis of the control scheme which is correct,the yarn tension control experiment platform is constructed,by means of the analysis of experimental data,it is concluded that the design scheme can meet the design requirements and achieve good control effect.