Analysis of a Hybrid Field-Modulated Linear Generator For Wave Energy Conversion

Direct-drive wave energy converter (DD-WEC) is limited by low power density caused by low direct-drive speed. A tubular hybrid field-modulated linear generator is proposed to improve the performance of DD-WEC. The generator adopted a field-modulated design to increase the output voltage of the linear generator. A hybrid excited field coil can be used to adapt to different wave situations and effectively improve the output performance of this kind of generator. The operation of the proposed generator is analyzed, and the generator performance is evaluated through finite element method and compared with those of three other generators, namely, a field modulated linear generator with parallel magnetic-circuit, a secondary surface PM field modulated linear generator, and a secondary surface PM fractional-slot linear generator. Results show that the proposed generator exhibits high power density and low cogging force. The steady output power and output voltage of are marginally higher in the proposed generator than in the conventional generators.