Research On Force Ripple Compensation Of Permanent Magnet Linear Synchronous Motor

Permanent magnet linear synchronous motor(PMLSM)has the characteristics of high speed,high precision,high thrust density and high dynamic response.PMLSM eliminates the rotating mechanical transmission mechanism,which can realize the direct drive movement and reduce the mechanical loss caused by friction.However,this kind of direct drive structure will also make various external disturbances such as thrust ripple add to the linear motor without buffer,making the motor's ability to resist external force disturbances decline.How to reduce the impact of thrust ripple on the operation of linear motor is the key to ensure the excellent performance of linear motor.In this paper,the control system is optimized to reduce the impact of thrust ripple on linear motor operation.First,this paper starts from the causes of thrust ripple,and carries out mathematical modeling of all kinds of thrust ripple.In order to analyze the data of thrust ripple,a method of collecting the data of thrust ripple is designed,and an off-line identification scheme is designed for the data of thrust ripple,and the approximate mathematical model of the thrust ripple is obtained.Second,in order to realize the on-line observation of thrust ripple,this paper establishes the state space expression of the linear motor motion system,and designs two kinds of thrust ripple observers,namely the Luenberger observer with constant gain and the kalman filter with variable gain respectively.The algorithm establishment process,parameter design and stability analysis of kalman filter are introduced in detail.Using the data of thrust ripple obtained from the observer,the current compensation is used to reduce the influence of thrust ripple on the operation of linear motor.Third,considering the shortcoming of the traditional kalman filter,an incremental kalman filter is designed from the mathematical model of linear motor,which can realize the order reduction operation of the observer.A priori parameter design method is proposed for the improved thrust ripple observer.Last,on the basis of theoretical analysis,the drive control platform of linear motor is built,and the hardware circuit design and software system design of the control system are introduced.The true value of thrust ripple of linear motor is measured by force sensor on this platform,which is used for comparative experiment.The thrust ripple data acquisition experiment was carried out on the platform,the data were identified off-line and the approximate mathematical model was obtained,and the feedforward compensation was carried out online,and the improvement of the stability of the linear motor was analyzed.On this basis,the thrust fluctuation compensation experiments with the conventional and improved kalman filter as thrust ripple observers are carried out,and the performance and the calculated load of the system are compared and analyzed.