Performances Analysis of a Tubular Permanent Magnet Linear Generator with 120° Phase Belt Toroidal Windings

Tubular permanent magnet linear generator (TPMLGs) is widely used in direct drive wave energy conversion system (DD-WECs) due to their simple structure, friendly maintenance and high efficiency. Unfortunately, the power density of this type of generator is relatively small due to their low operation speed. To improve the power density, a TPMLG with 120° phase belt toroidal windings (120°-TPMLG) is proposed in this paper. Firstly, the structure of the 120°-TPMLG is introduced, and its operation principle is analyzed by describing the variation of the magnetic field generated by the permanent magnet. Furthermore, to investigate the performances and the unique advantages of the 120°-TPMLG, a traditional toroidal windings tubular permanent magnet linear generator (T-TPMLG) is compared with the generator based on the similar dimensions. Finally, the unstable AC electricity generated by the generators is rectified, which can transform the AC electricity to the stable DC electricity for supping the equipment. The results indicate that the proposed 120°-TPMLG has superiority in detent force, power density and generation efficiency than the T-TPMLG.