Nonlinear Model Predictive Speed Control with Variable Predictive Horizon for PMSM Rotor Position

Predictive horizon in model predictive control (MPC) or nonlinear MPC (NMPC) is a constant value which limits the performance of system. A nonlinear model predictive speed control (NMPSC) with variable predictive horizon during each sampling period is proposed in this paper, and applied into the rotor position control system of permanent magnet synchronous motor (PMSM). The prediction horizon can be adjusted to improve control accuracy and decrease calculation burden. The proposed method is compared with the improved NMPSC strategy with extra weighting factors, and it exhibits high performances in tracking process, robustness of stator resistance and magnet flux linkage mismatches. Even with rated load torque, the proposed method still achieves high servo stiffness. Simulation and experimental results verify the effectiveness and feasibility of the proposed control strategy, under the condition of a sinusoidal reference which makes system operate in transient state continuously.