Research On Speed Loop Auto-tuning Technology Of Ac Servo System

Permanent magnet synchronous motors have the advantages of small size,light weight,high power density,high efficiency,small torque ripple,thus are widely used in AC servo systems.However,due to the limitation of the technology,there are still deficiencies in the research of high performance AC servo systems in China compared with the research results abroad,which is mainly reflected in the fact that the domestic products ge nerally do not have the parameters self-tuning function and the mechanical resonance suppression function.Therefore,in this paper,the speed loop of AC servo system is taken as the research object.For the permanent magnet synchronous motor and AC servo system,the offline inertia and online inertia identification,the self-tuning of the speed loop controller parameters and the suppression of the mechanical resonance are studied in this paper.It is of great significance to promote the development of AC servo systems in high-end CNC machining systems and in the field of industrial automation.Firstly,according to the mechanical motion equation of permanent magnet synchronous motor,the offline inertia identification method is designed by giving the triangle wave command.The recursive least squares method is used to identify the online inertia of the motor online;The steady state error and other issues have made specific improvements by the identification method,and an online inertia recognition online identification strategy based on variable forgetting factor recursive least-squares method has been implemented;and a speed loop controller has been developed based on the speed ring mechanical parameters which have been obtained through parameter identifi cation.Secondly,the cause of mechanical resonance is analyzed.The mathematical model is abstracted based on the physical structure of the dual-inertia system,and the output under a given input is analyzed in the time domain to determine the amplitude and frequency of the mechanical resonance.Bode diagrams and other mathematical tools in the frequency domain are used to analyzed this system.The frequency spectrum of the inertial system and the entire AC servo system is analyzed to determine the specific relationship between the mechanical resonance frequency and related parameters,which lays a theoretical foundation for the related research on mechanical resonance suppression.Next,on the basis of the previous section,the mechanical resonance suppression method based on white noise is studied.White noise is given as the input signal.At the same time,the output signal is read and subjected by Fast Fourier analysis.The notch filter is designed based on the analysis result and the filter parameters are adjusted adaptively to achieve mechanical resonance suppression.Finally,based on the theoretical analysis,a dual-inertia system drive control experiment platform is set up,hardware and software algorithm of the drive controller is designed,feasibility and effectiveness of the speed loop auto-tuning method are verified through experiments.