Pole-modulated PM direct-drive generator for wave energy conversion

This paper describes the general design considerations and analysis for a direct-drive generator for wave energy conversion. Direct drive wave energy converters have been proposed in view of the disadvantage of mechanical complexity and low conversion efficiencies in conventional wave energy converters. By directly coupling an electrical generator to an oscillating wave energy device, it is suggested direct-drive power take-off could be a viable alternative to hydraulic based systems. The operation fundamentals, combined with FE (Finite Element) analysis are discussed with the target operation in the low speed high torque requirements. The pole modulated design converts the slow motion to a higher generator output frequency. The generator design principle, comparisons between different topologies, as well as prototype designs at different speeds are analyzed and compared with conventional permanent magnet (PM) type machines.