Research And Realization Of Mechanical Resonance Suppression Of Servo System

Three-phase permanent magnet synchronous motor has been widely used in the field of AC servo control because of its many advantages.When the servo motor drives the load to run,the drive shaft of the connecting device between the motor and the load is often not completely rigid,which will cause a flexible transmission between the servo control systems,and the flexible transmission will inevitably produce a mechanical resonance.The existence of mechanical resonance will cause obvious and continuous oscillation of the speed and electromagnetic torque of the servo control system,which will directly affect the response speed and control accuracy of the control system.At the same time,it will limit the increase of the system bandwidth response width.As a result,system instability,damage to the drive linkage,and broken shafts occur,making the servo device less than a pre-designed target.Therefore,the study of the mechanical resonance suppression problem of the servo system becomes extremely important and urgent.In this paper,the status and existing problems of the mechanical resonance in the servo control system at home and abroad are described firstly.The servo motor control theory is studied and the servo motor mathematical model is established to discuss the principle and method of the vector control of the motor in the platform.The motor-load two-inertia mathematical model was used to analyze the mechanism of mechanical resonance in the servo control system,and then the influence of the inertia ratio of the load motor and the stiffness coefficient of the transmission shaft on the mechanical resonance was discussed.The accurate identification of resonant frequency points is the key to passive suppression of resonance.In the following,the identification methods of resonant frequency characteristics in servo systems are studied,including direct measurement method,sweep frequency method,and rotational speed current analysis method.Swept frequency method is the recognition of excitation signals with rich frequency components such as given chirp signal,which belongs to off-line frequency characteristic identification;speed current analysis method is to collect speed errorsignal or quadrature axis current signal when system resonance occurs.After the FFT spectrum analysis method,belongs to online resonant frequency identification.In this paper,the online resonant characteristics are identified and the correctness of the method is verified by matlab simulation.Then based on the previous analysis,a kind of servo system resonance suppression scheme based on adaptive notch filter was designed,and the determination method of each parameter of notch filter was proposed.The program was simulated in matlab and the speed loop oscillates well.Finally,the previous design of the program in the DSP chip for the TMS320F28335 software programming verification.First,adjust the speed of the speed loop to 500 rad/s to make it oscillate resonantly.After adding the designed resonance suppression algorithm,observe that the speed oscillation is significantly reduced.Experimental results show the feasibility and effectiveness of the scheme.