Intelligent Model-Following Position Control for PMSM Servo Drives

In this paper, an intelligent robust position controller for permanent-magnet synchronous motor (PMSM) servo drives is proposed. The intelligent robust position controller consists of a two-degrees-offreedom integral plus proportional & rate feedback (2DOF I-PD) controller in addition to an on-line trained neural-network model-following controller (NNMFC). This controller, 2DOF I-PD NNMFC, combines the merits of the 2DOF I-PD controller and the NNMF controller for PMSM servo drives position control. A systematic mathematical procedure is derived to find the parameters of the 2DOF I-PD position controller according to the required specifications for the PMSM servo drive system. Then, the resulting closed loop transfer function of the servo drive system including the current control, speed control and position control loops is used as the reference model. In addition to the 2DOF I-PD position controller, a neural-network model-following controller whose weights are trained on-line is designed to realize high dynamic performance in disturbance rejection and tracking characteristics. According to the model-following error between the outputs of the reference model and the PMSM servo drive system, the NNMFC generates two adaptive control signal which are added to the 2DOF I-PD speed controller output to attain robust model-following characteristics under different operating conditions regardless of parameter variations and load disturbances. A computer simulation is developed to demonstrate the effectiveness of the proposed 2DOF I-PD NNMF position controller. The results confirm that the proposed 2DOF I-PD NNMF position controller produces robust performance, rapid and accurate response to the reference model regardless of load disturbances or PMSM parameter variations. Key-Words: PMSM Servo Drives, Vector Control, 2DOF I-PD Controller, Neural Network (NN), Model Following Controller (MFC).