| Permanent magnet synchronous linear motor(PMSLM)plays an increasingly important role in the field of high precision control.The ripple force,one of the main external disturbances,seriously affects the position tracking accuracy of the control system.Therefore,the study of ripple force compensation strategy is of great significance to improve the control performance of linear motor.In order to compensate the ripple force of linear servo system on-line,the following research has been accomplished in this paper.Firstly,the cause of ripple force is analyzed,and its mathematical model is established to prepare theory for on-line compensation.Secondly,an ripple force compensation method based on IREFOP is proposed.The characteristic value of ripple force is obtained at low and uniform speed.On this basis,the parameters of ripple thrust model are identified online by IREFOP and recursive least square method.Because the traditional REFOP algorithm has too much computation,it improves the update strategy of variable matrix database,and improves the real-time performance and running speed of the algorithm.The feed-forward compensation component is constructed based on the identification results to suppress the ripple thrust.To overcome the disadvantage that the above method can only obtain eigenvalues at low and uniform speed,an on-line ripple thrust compensation method based on MP algorithm is proposed.An atomic library with time-frequency characteristics of ripple thrust is constructed.The optimum atoms are obtained by matching the current thrust current with the atoms in the atomic library.The eigenvalues and model parameters are analyzed.The feed-forward compensation component is constructed based on the identification results to suppress the ripple thrust.Finally,a simulation experiment platform is built in Matlab/Simulink to verify the online ripple thrust compensation method based on IREFOP algorithm and MP algorithm,and the results prove its effectiveness. |
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