A Novel Tubular Partitioned Stator Flux-Reversal Permanent Magnet Linear Machine for Direct-Drive Wave Energy Generation

A novel tubular partitioned stator flux-reversal permanent magnet linear machine (PS-FRPMLM) is proposed for direct-drive wave energy generation. It consists of four flat PS-FRPMLMs and a moving aluminum tube, which not only combines the merits of permanent magnet machines and flux-reversal machines but also overcomes the space constraint between the permanent magnets and electric loadings. First, the topology and the operation principle are presented. Then, the proposed machines with different slot/pole combinations, i.e., 6/4, 6/5, 6/7, and 6/8, are optimized to obtain the maximum no-load electromotive force (EMF). Furthermore, the performances of these proposed machines are compared with those of conventional tubular FRPMLMs in both no-load and on-load states. The results show that this novel structure possesses lower cogging force, better PM utilization, and higher efficiency in the on-load state, which proves it to be suitable for application in direct-drive wave energy generation. Finally, a prototype of a single flat PS-FRPMLM is tested to verify the predicted finite element (FE) results.