Composite Single-Loop Model Predictive Control Design for PMSM Servo System Speed Regulation Based on Disturbance Observer

In order to optimize the control performance of the permanent magnet synchronous motor (PMSM) in the presence of strong disturbances and model uncertainty, a composite single-loop model predictive control (MPC) based on disturbance observer (DOB) is studied in this paper. Firstly, a DOB is employed to estimate the lumped disturbance including the uncertain parameters and the external disturbance in real time. Afterwards, benefitting from model-based design, estimations are introduced into the prediction model of the PMSM, then a composite single-loop MPC is designed based on this model. Finally, the optimal control input is obtained, by introducing Lagrange vector and solving the quadratic programming problem with constraints. Simulation results show that the proposed composite control method has a faster transient response and a better disturbance rejection ability. In addition, compared with the generally cascade structure, only the predictive horizon and the observer poles are needed to be adjusted, so it provides a more practical optimization algorithm for the engineering application.