Study On Disturbance Suppression Of The Tubular Permanent Magnet Synchronous Linear Motor Servo System

The high-grade CNC machine tools require strict performance indicators such as higher speed,bigger acceleration and higher accuracy.Hence,the linear motor,which simplifies the intermediate drive mechanism,contributes to guaranteeing the performance index.However,the unique structure also means that external disturbance and the load variation can affect the mover directly.Hence,the disturbance suppression is a key problem to be solved for the linear motor system.To reduce effects of the disturbance and improve performance of the system,this paper researches the disturbance suppression.The researches are based on a tubular permanent magnet linear synchronous motor(TPMLSM).According to the topological relations between rotating motor and the linear motor,the mathematical model of the linear motor is deduced.Further model which takes the asymmetry of inductance values into account is also obtained.Vector control methods and principles of space vector modulation are summarized.On the basis,a three closed-loop vector control system,which take the strategy of_di(28)0,is established.Simulations and experiments of the system prove the effectiveness and practicability.The typical disturbance situations of the system are analyzed,namely,the persistent disturbance represented by the detent force and the instantaneous disturbance represented by the impact.By means of simulation calculation,the effects of the model-based and the non-model-based disturbance suppression methods are studied.The advantages and disadvantages of the two methods are illustrated,and a disturbance suppression structure which combines both of the methods is proposed.The structure is verified by simulations and experiments,and the results prove the effectiveness.The detent force of the linear motor will affect the initial position estimation directly.Through the equivalence,the effects of detent force on the pre-positioning are analyzed in detail.An iterative estimation algorithm is proposed to estimate initial position of the pre-positioning under detent force.The correctness of the algorithm is verified by simulations and experiments.The phases of three-phase inductances in linear motors are asymmetry,which aggravates the thrust fluctuation and affects the performance and accuracy.In this case,the traditional coordinate transformation can't reflect the asymmetry very well.Hence,a novel non-orthogonal coordinate system is proposed and the corresponding transformation matrix is derived.Then the mathematical model of the motor can be deduced.Based on the novel coordinate transformation matrix and the corresponding motor mathematical model,a compensation structure on the given-signal side is proposed to suppress effects of the phase asymmetry.The effectiveness and compatibility of the control structure are verified by further simulations and experiments.