Review of magnetic gear technologies and their applications in marine energy

Abstract

The marine energy industry is in its early stages but has a large potential for growth. One of the most significant challenges is the reduction of operation and maintenance costs. Magnetic gears (MGs) offer the potential for long periods between maintenance intervals due to their frictionless torque transmission which could reduce these costs. This study presents a summary of the state of the art in MG technology and then investigates its potential for marine energy applications. A brief overview is given of the state of the marine energy industry and the environment in which marine energy converters (MECs) operate. A short history of MG development over the past century is then presented followed by a discussion of the leading MG technologies and their relative advantages. In order to demonstrate the potential of MGs in marine applications, the current technologies, i.e. mechanically geared and direct drive machines, are examined in terms of sizing, reliability and economic value using previous studies on a similar technology, namely wind. MGs are applied to four types of MECs to demonstrate how the technology can be incorporated. The potential to deploy at scale and potential obstacles to this are then discussed.

Design and optimization of yokeless magnetic gear with asymmetric Halbach permanent magnet array for electric vehicle powertrain

“…Magnetic gear (MG) provides the solution for replacing the mechanical gearbox in the electric vehicle propulsion system [1][2][3][4][5] for its inherent advantages of high transmission efficiency, overload protection, low working noise, and physical isolation [6][7]. To tap the potentials of industrial application, researchers focus on the MG, including radial-flux [8][9][10] MG, axial-flux MG [11,12], and magnetic-geared machines [13][14][15], for finding the better performance solutions. However, due to the limit of machine structures, all those MGs employ rotor iron cores to form the magnetic circuit and reduce the magnetic reluctance, which becomes the major weight of the machine.…”

Resonance Control Based on Hydrodynamic Analysis for Underwater Direct Drive Wave Energy Converter

“…The linear generator should adopt low-speed design for nature of wave, but thus leads to lower output voltage and power density [19]. So increasing the translator stroke of linear generator is the research direction at present, it mainly focuses on the application of magnetic gear technologies in PTO for the limited reciprocating stroke of wave [20]. When the buoy oscillates slightly underwater to keep the hydrodynamic parameters as constant as possible, the motion stroke and field traveling velocity can be expanded by the linear-rotating axial flux permanent magnet generator (LR-AFPMG) and then the power density can be increased.…”

Magnetic field‐modulated linear permanent‐magnet generator for direct‐drive wave energy conversion

“…These generators include linear permanent magnet (PM) synchronous generators [2,3], doubly-fed linear generators [4], switched reluctance linear generators [5,6], transverse-flux PM linear generators [7], linear permanent-magnetassisted synchronous reluctance machines [8], and so on. Since the travelling magnetic field runs at the same low speed as the mover, such linear generators have been adopted with a multi-pole design and suffer from problems such as large volume, low power density, and low efficiency in direct-drive WEC systems [9].…”