Inner Loop Design for PMLSM Drives with Thrust Ripple Compensation and High-Performance Current Control

To realize the precise thrust force control in permanent magnet linear synchronous motor (PMLSM) drives, this paper studies a novel design method of the high-performance current inner loop. First, to increase the control bandwidth, an optimized predictive current controller, which takes account of the one-step delay issue, is presented on the basis of the discrete-time model of the PMLSM. Second, as disturbance factors, the thrust ripple and parameter variation can influence the input and output command of the current controller, respectively. Therefore, an improved sliding mode algorithm with the variable exponential reaching law is introduced to suppress these two disturbances simultaneously, and the stability analysis is given to prove the convergence of the algorithm through the Lyapunov stability theory. Finally, a precise experimental platform on account of the aerostatic guide is established, and experimental results are given to demonstrate the feasibility of the proposed control scheme.