Comparison of permanent magnet generators for a very low speed renewable energy application

This paper describes the design of a very low speed direct-drive brushless permanent magnet generator for use in a Bristol cylinder device which is used for generation of electrical energy from sea waves. It studies both air-gap wound and slotted stator types of machine. It studies the design of a scaled down machine using air-gap windings then scales the machine up to obtain a full-scale generator. A comparison is made to a slotted alternative. The performance is studied in steady state terms.