A vector control scheme for a PMLSM considering a nonuniform flux distribution

We consider the permanent magnet linear synchronous motor (PMLSM) in which the primary winding is moving between permanent magnet arrays. As a means of increasing the stroke of the PMLSM, we consider the problem of controlling the force even when the primary winding is partially out of the permanent magnet field range. As the primary winding travels beyond the PM field range, the outed portion of winding experiences zero flux. Due to the outed part of the winding, the generated force will be reduced with the increase of the force ripples. In this work, we analyze the back EMF variation when the winding is out of the PM field range and propose a compensation method. Finally, we have demonstrated the effectiveness of the proposed method through experimental results.