Optimal, Combined Speed, and Direct Thrust Control of Linear Permanent Magnet Synchronous Motors

An optimal control scheme synthesized using a linear quadratic regulator-based approach for combined speed and direct thrust force control of permanent magnet synchronous motor (PMSM) is proposed. A novel multiple-input-multiple-output state space model, having stator flux, thrust force, and mover's speed as states, is formulated for the linear PMSM where the state transition matrix is independent of mover's speed. An optimal linear state feedback control scheme is designed using the optimal linear quadratic regulator technique. Integral action is added to the designed control scheme by state augmentation to minimize the steady-state error. Experimental results clearly prove that the proposed optimal control scheme results in a faster transient response of speed and force with improved steady-state regulation of force and flux when compared with the state of the art.