Research On Mechanical Resonance Analysis And Suppression Method Of Permanent Magnet Synchronous Motor Servo System

Permanent magnet synchronous motor(PMSM)servo system has the advantages of high control accuracy,fast response speed and high degree of automation.It is widely used in precision control of CNC machine tools,industrial robots,astronomical telescopes,radar,and other fields.With the development of servo control technology,it is necessary to fully study the influence of mechanical transmission mechanism on control performance.The elastic factors of the lead screw,guide rail,coupling and other components in the mechanical transmission mechanism of the servo system cause mechanical resonance,which worsens the performance of the servo system and affects the control accuracy.On the other hand,because the servo drive mechanism is a high-dimensional nonlinear system with many random disturbances,it will also be affected by random factors when determining the mechanical parameters,resulting in the random drift of the resonance point near the theoretical value;And with the change of equipment working conditions and the increase of service life,the mechanical parameters such as stiffness coefficient,inertia ratio and damping coefficient in the mechanical transmission mechanism change,causing the change of mechanical resonance point,which makes it difficult to effectively suppress mechanical resonance.The technical difficulties caused by the mechanical resonance problem are still in the exploration stage,and the research on the corresponding technologies of commercial servo systems lacks highlights at home and abroad.In this dissertation,the mechanical resonance of the servo system is studied as follows:(1)Through the mathematical model of the servo mechanical resonance system,the resonance mechanism is analyzed,and the influence of mechanical parameters on the resonance characteristics is clarified,which lays a theoretical foundation for the design of mechanical resonance suppression strategies.(2)Aiming at the unknown mechanical parameters of the servo system,the Gauss Markov two mass mechanical system model is established based on the Gaussian process,the expression of variance unbiased estimation is derived,the system inertia,damping,stiffness,load torque and other parameters are identified by the least square method.Compared with the existing parameter identification methods,the two-stage identification is simplified to one identification,and the parameter identification is realized in one step to avoid errors in the intermediate link,so the results are more accurate,providing an accurate data basis for the subsequent research on key technologies.(3)Aiming at the phenomenon of random drift of resonance point caused by random factors,a rotating speed negative feedback resonance control method based on control chart and optimization theory is proposed.Firstly,the torque analysis method is used to determine the rotating speed negative feedback controller;Secondly,the control line is determined according to the variation range of resonance point and amplitude and the 3σ principle of normal distribution;Then,the optimization algorithm is used to optimize the design of the rotating speed negative feedback resonant controller,which can effectively and accurately suppress the mechanical resonance of the random drift of the resonant point.Compared with the widely used conventional active suppression method,this method can not only effectively suppress the resonance,but also take into account the stability of the system,so that the tracking error is minimized and the system control accuracy is the best;Compared with manual adjustment of parameters,the optimization algorithm has the characteristics of less time consumption,accuracy and speed.Aiming at the problem of resonance point drift caused by the change of mechanical parameters in the servo system,an online resonance suppression method is proposed based on the mechanical parameters identified by the least square method.Firstly,a fast searching algorithm based on multi frequency sinusoidal signal is proposed to search the drift resonant frequency online;Then,the optimization algorithm is used to optimize the design of the notch filter to achieve rapid and real-time suppression of resonance.This scheme can not only effectively solve the problem of notch filter failure caused by resonant frequency drift,but also minimize the phase angle loss and maintain the stability of the system;Finally,the method is applied to the PMSM servo system,and the simulation and experimental results show that the method has good performance of mechanical resonance suppression and robustness.