Tubular-Linear Synchronous Machines: Application to Wave Energy Harvesting

The chapter is aimed at one of the emergent sustainable applications, that is wave energy (WE) harvesting using appropriate converters (WECs). The survey is started by a classification of WECs according to the technology of their power take-off systems with emphasis on the topology of the integrated generator including rotating and linear topologies. Linear PM synchronous machines represent the most viable candidates thanks to their high force density and energy efficiency at low speeds. Of particular interest is the inset PM (IPM) tubular topology which offers an increase of the energy efficiency and an intrinsic-cancellation of the radial attractive forces. The IPM tubular-linear synchronous machines (T-LSMs) are then the subject of modelling considering its magnetic equivalent circuit (MEC). Following its synthesis, the MEC is solved considering an iterative numerical procedure. The preliminary results reveal that the IPM T-LSM features are affected by the end effect. Two design approaches dedicated to the minimization of such a drawback are proposed and their effectiveness checked by finite element analysis. The survey is achieved by an extension of the validity of the proposed model to the time-varying features by incorporating the mover position in the MEC.