A Novel Superconducting Magnet Excited Linear Generator for Wave Energy Conversion System

In almost every permanent-magnet linear generator (PMLG), demagnetization would greatly degrade the electricity generation capability over time. This paper proposes a novel electromagnetic linear generator (EMLG) for direct-drive power generation from oceanic waves, which consists of superconducting magnets instead of conventional permanent magnets to create sufficiently strong magnetic field to produce electricity. The proposed generator can avoid the demagnetization problem of the conventional PMLG. To verify the feasibility of the new concept, a generator is designed. Yttrium barium copper oxide is used to make the superconducting magnet. The finite-element analysis is performed by using the commercial software package ANSYS/ANSOFT to analyze the performance of the proposed EMLG, 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. Magnetic pole shoes are designed in such a way that they can effectively minimize force ripples and cogging force. The results are analyzed and discussed. The results demonstrate that the proposed generator almost eliminates the demagnetization problem of the conventional PMLG with some other built-in advantages. The maximum efficiency of the proposed generator is found to be approximately 96% without considering frictional and other mechanical losses. The results demonstrate excellent features of the proposed generator.