Analysis and design of a novel linear generator for harvesting oceanic wave energy

In almost every permanent magnet linear generator (PMLG), demagnetization would greatly degrade the electricity generation capability over time. This paper proposes a novel PMLG which consists of a permanent magnet excitation generator (PMEG) to supply electrical excitation to the field winding of an electromagnetic linear generator (EMLG) which functions as the main power generator. The proposed generator can reduce the demagnetization problem of the conventional PMLG. The finite element analysis is performed by using the commercial software package ANSYS/ANSOFT for designing the proposed PMLG, and the genetic algorithm has been used to find the optimal pole size, pole pitch, air gap length and load variation to maximize the output power. Special m-shaped stator core is designed for the PMEG to minimize the leakage flux and cogging force. The voltage, current, power, magnetic flux density, force components and applied force are also analyzed and discussed.