Spatial harmonic analysis on a permanent magnet linear generator with Halbach array for direct‐driver wave energy conversion

Abstract

AbstractA tubular permanent magnet linear generator (TPMLG) with Halbach array magnetization is proposed to extract wave energy. The magnetic field is analyzed by analytical analysis and verified by numerical analysis. The air‐gap flux density of TPMLG with Halbach array magnetization has a better sinusoidal shape than quasi‐Halbach and other magnetization based on the spatial harmonic analysis. The harmonic component of flux density varies with the degree of permanent magnet magnetization, through optimizing the angle α (α is the angle between the z‐axis and orientation of magnetization), and the harmonic component is smallest when the angle α equal to π/4. Meanwhile, the amplitude of Br in air‐gap region reaches maximum. Analytical analysis proves that TPMLG with Halbach array magnetization can improve generator performance and power density. Finally, a prototype is manufactured and applied to a direct‐drive power take‐off system experiment. Simulations and experimental results demonstrate that it is an effective method for direct‐drive wave power take‐off system.