The direct-drive radial flux synchronous generator is considered as the modern wind turbine drive train. Both the electrically (e.g., Enercon) and permanent magnet (PM; e.g., Siemens) excited direct-drive generators are gaining popularity on the market today. Compared with the matured geared counterpart, the electrically excited direct-drive generator is heavier and more expensive but more reliable per unit capacity. The PM-excited generator is expensive, is simpler in electromechanical design, has a high power-to-weight ratio, and yields a higher energy conversion efficiency than its electrically excited equivalent. The PM generator technology has the potential to yield the highest energy-to-cost ratio. However, standardization of this direct-drive generator parts/subassemblies may overcome the existing cost barrier. Most current literature focuses on PM generator wind turbine technology, specifically on generator energy conversion optimization, and the scalability of technologies to capacities in access of 5 MW. Strangely, PM generator's mass and cost reductions through optimized structural design incorporating manufacturing, transportation, and installation constraints are less studied. This paper solely focuses on the mechanical and structural design aspects of large radial flux synchronous PM generators specific to direct-drive wind turbines. Generator topologies such as the common iron-cored and unconventional air-cored generator are discussed. However, design considerations specific to the iron-cored generator topology are studied. The design considerations investigated involve the geometries and the configurations of rotor/stator active and inactive structures, the interfaces, and the conductor/PM mounting methods.

Pinardi et al. Marine Monitoring to Services resulting from the observations and data management. Future developments should enhance coordination in these three program areas by considering the inclusion of new and emergent observing technologies, the interoperability of met-ocean data assembly centers and the establishment of efficient research to operations protocols, in addition to better fit-for-purpose customized services in both the public and private sectors.

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The modular slip‐synchronous permanent magnet generator (SSPMG) is viewed as an induction‐synchronous machine pair that is electromagnetically decoupled by a free‐rotating rotor that in turn houses two different sets of permanent magnets. This machine pair combines the advantages of both conventional induction and permanent magnet synchronous machines. It therefore has the potential to realize a new path in reliable, robust and cost‐effective wind turbine drivetrains. However, which electromagnetic SSPMG topology is best and how does it compare with conventional drivetrain designs for various capacities? To date, the most published SSPMG advances are specific to winding design, torque quality and performance optimization in the small capacity range. This paper presents optimized analytic electrical designs of modular, radially and axially separable, radial flux SSPMG topologies of capacities ranging from 100 kW to 5 MW. Designs are based on lumped analytic models and are optimized for minimum specific active mass (mass/torque). A rated efficiency of 95 % and an inductive power factor of 0.95 are applied to all designs. The analytic models are validated with transient two‐dimensional finite element analysis results. The best SSPMG topologies are determined and compared with conventional drivetrain designs. The axially separable topology seems to be the best SSPMG design. Copyright © 2014 John Wiley & Sons, Ltd.

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