Special Synchronous Linear Actuators. Structures and Performances

The linear displacement of a mechanical load can be carried out with several processes by either indirect or direct linear actuators. For long (and possibly unlimited) courses, the direct drives perform better, with the linear induction machines and the synchronous machines being better adapted. For small strokes, electromagnets and voice-coil actuators prove to be the most suitable. This paper focuses primarily on synchronous linear drives. After recalling the main selection criteria for linear actuators, we briefly present the various possible topologies of synchronous actuators. Several examples of linear electrical structures to be developed, especially those at the LESiR facility, as well as their performances are then provided. In particular, we will describe two original structures and their respective performances: a low-cost actuator called "flux-switching", and multi-air gap structures which allow attaining a high specific thrust.