Speed Ripple Minimization For Permanent Magnet Synchronous Motor Drives

Permanent magnet synchronous motor(PMSM)drives has been widely applied in aerospace,traction drive,robots,electric vehicles and other industrial fields because of the advantages of high efficiency,good control performance,high power density and so on.The non ideal factors such as dead time effect,flux harmonic and current sampling error can cause the speed ripples,which seriously weakens the steady-state control performance of the PMSM drives.To solve this problem,this paper studies the speed ripple minimization algorithm from two aspects of traditional proportional integral(PI)control and linear quadratic optimal control.Aiming at the problem of speed ripples in PMSM vector control system based on PI controller,this article estimates the main order speed ripple components by Kalman filter,and embeds these estimated components in forward channel of speed loop by paralleling them with the PI controller.Then,according to attenuation degree of periodic disturbance torques,the values of proportional gain compensation corresponding to these speed ripple components are selected.Thus these periodic disturbance torques are suppressed.The experimental results show that the proposed strategy can efficiently improve the steady-state performance of the PMSM drives.In order to improve the steady-state performance and reduce the influence of non ideal factors for PMSM drives based on the traditional linear quadratic optimal control,this article establishes an augmented state space model containing information of periodic disturbances according to the characteristics and distribution of periodic disturbances in PMSM drives.Then,based on the model,the linear quadratic optimal control law of state feedback controller is solved.Because it is incapable to directly measure the augmented state variables related to periodic disturbances in the augmented state space model,this paper designs a periodic disturbance observer to estimate these augmented state variables.Thus the state feedback control is realized.The experimental results show that the proposed method can efficiently improve the steady-state performance of the PMSM drives without sacrificing dynamic-state performance.