Research On Anti-electromechanical Torsional Vibration Control Of Large-power Drive System

Large-power drive system is a multi mass elastic drive chain,which has electromechanical resonance and torsional vibration.This phenomenon will cause equipment damage and affect the operation characteristics and product quality.For a long time,the anti electromechanical torsional vibration control of electric drive system is an important subject in the field of electrical and mechanical science.Aiming at the mechanical and electrical torsional vibration of large-power drive system,the dynamic model of drive system,torsional vibration model of rolling mill drive,load observer control,virtual inertia and virtual damping control are deeply studied in this paper.The main contents are as follows:Firstly,the two mass electromechanical dynamic model of large-power drive system is established,and the transfer function of the two mass electromechanical dynamic model is derived.The Bode diagram is used to analyze the influence of mechanical parameters on the resonance characteristics of the drive system.It is proposed that the moment of inertia ratio will change the resonance frequency of the system,that is,the decrease of the inertia of the motor will increase the resonance frequency,and vice versa.In this paper,the transmission system of large rolling mill is studied,which is simplified as multi mass elastomer transmission chain.The mathematical model of mechanical and electrical torsional vibration of rolling mill is established,and the frequency characteristics of the system are studied.The torsional vibration amplification factor TAF is calculated.The effects of resonant frequency,mechanical parameters and nip in time on TAF were analyzed.Under the condition of constant load inertia,the reduction of motor inertia is beneficial to the reduction of TAF.For the load observer control system based on disturbance invariance,this paper points out that under the condition of sudden load,the load observer positive feedback control can significantly reduce the dynamic speed drop,but it makes the resonant frequency decrease,the resonant point of frequency characteristics shift to the left,and aggravates the oscillation of the connecting shaft torque.At the same time,it is pointed out that the negative feedback control of load observer can increase the resonance frequency and shift the resonance point of frequency characteristic to the right,which can obviously reduce the torque oscillation of connecting shaft,but aggravate the dynamic speed drop.The effectiveness of the proposed theory and method is verified by simulation and electromechanical torsional vibration experiment.This paper presents a "virtual inertia" control,which can change the control ratio of the system,adjust the inertia ratio,change the resonance frequency,and achieve the effect of suppressing electromechanical torsional vibration.In this paper,the mathematical theory of virtual inertia control is analyzed in detail,and the effect of virtual inertia control on torsional vibration is verified by simulation and electrical torsional vibration experiment.In this paper,a "virtual damping" control system with inertia link in the feedback channel and a simple "virtual damping" control system with differential feedback of motor speed to current control are proposed.The control only changes the amplitude of the transfer function at the resonance point without changing the resonance frequency of the system,so as to achieve the "damping" effect of suppressing the torsional vibration amplitude.In this paper,an experimental platform for torsional vibration of electric drive is built,and the simulation and experimental results verify the effectiveness of the proposed theory and method.