Design Aspects of a Novel Topology Air-Cored Permanent Magnet Linear Generator for Direct Drive Wave Energy Converters

• Published in: IEEE transactions on industrial electronics (1982) Vol. 59; no. 5; pp. 2104 - 2115
• Main Authors: Vermaak, R., Kamper, M. J.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-05-2012; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Air-cored; analytical models; Attraction; Coils; Copper; design optimization; direct drive; Direct power generation; electrical machines; Finite element analysis; finite element methods; Generators; linear generator; Magnetic flux; Mathematical analysis; Mathematical models; nonoverlapping windings; permanent magnet (PM); Stators; Studies; Topology; wave energy; Windings
• ISSN: 0278-0046; 1557-9948
• DOI: 10.1109/TIE.2011.2162215

Direct drive wave energy converters are attractive due to the elimination of intermediate mechanical power conversion stages. Longitudinal flux (LF) linear generators with iron-cored stators have so far been dominant in experimental direct drive WECs, but suffer from high bearing loads and unwanted end effects. A novel linear air-cored topology is presented in this paper which eliminates most of the end effects associated with LF iron-cored machines as well as the attraction forces between iron-cored stators and magnet translators. The attraction forces between the opposing sides of the translators of double-sided air-cored machines are also ideally eliminated. An analytical model and an exhaustive optimization procedure for finding the minimum active mass subject to certain performance specifications are developed for the novel topology. Finite element analysis is used to verify and further analyze the model. First test results from a 1 kW experimental machine correspond well with designed values and confirm the feasibility of implementing the novel topology on a small scale.