Development and Wave Tank Demonstration of a Fully Controlled Permanent Magnet Drive for a Heaving Wave Energy Converter

Baker, Nick; Almoraya, Ahmed A.; Raihan, M. A. H.; McDonald, Steve; McNabb, Luke

doi:10.3390/en15134811

Cited by 4 publications

(4 citation statements)

References 45 publications

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“…Figure 1c showed the end winding and the active part of the winding. The cylindrical variant of G3 would need space for the end windings, and Figure 14 shows an example of a cylindrical linear machine, developed in [5], which consists of three single tooth windings. The end windings are highlighted as running in the direction of motion, axially into the plain of the figure.…”

Section: Cylindrical Variants and Manufacturing Issuesmentioning

confidence: 99%

An Innovative H-Type Flux Switching Permanent Magnet Linear Generator for Thrust Force Enhancement

2023

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In this paper, two H-type flux switching permanent magnet linear generators with outer-translator and inner-translator configurations are discussed and compared to a more conventional flux switching topology. The stators consist of H-Type modules housing circumferential coils and are surrounded by two annular permanent magnets. In conventional flux switching machines, the windings are orientated perpendicular to the direction of motion and the conductors twist around the magnets. In H-type topologies, the orientation of the windings is in the same plain as the magnets and parallel to the direction of motion, resulting in an increase in flux linkage. The proposed topologies are designed for a low operating speed and a large magnetic gap, as found in wave energy converters. All topologies are optimized using the Taguchi optimization approach with the goals of reducing force ripple and increasing the average thrust force and efficiency. The 2D finite element method (FEM) is used in the optimization stage to calculate the optimized parameters of the presented generators, after which the optimized structures are simulated using 3D FEM, and the results are extracted. The results of the optimization show that the H-type topologies deliver a 20% higher shear stress whilst offering an easier to assemble structure.

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Section: Cylindrical Variants and Manufacturing Issuesmentioning

confidence: 99%

An Innovative H-Type Flux Switching Permanent Magnet Linear Generator for Thrust Force Enhancement

2023

Self Cite

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“…The electrical generator will oscillate slowly compared to conventional generators implying the use of some form of magnetic gearing. Suitable topologies have been suggested by these [1,2,11] and other authors [12][13][14]. All of those designs rely on achieving a small magnetic gap.…”

Section: Selection Of Electric Machinementioning

confidence: 99%

“…a buoyant spring force. They therefore have a natural frequency, which can be calculated from (1), where k is the spring constant defined in (2) and m is the moving mass (3).…”

Section: System Modellingmentioning

confidence: 99%

“…technology for the whole category of devices. Similarly, many alternative electrical machine topologies exist which can be used to demonstrate direct drive power take off [1,2]. Despite a few well known examples [3,4], there is a relative lack of development and demonstration linking the two areas of wave energy development and slow speed electrical machine demonstration.…”

Section: Introductionmentioning

confidence: 99%

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Design of an integrated generator and heaving buoy

Baker,

Chambers,

Turkmen

2023

Proc. EWTEC

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The power take off for wave energy remains one of the key technical challenges that must be overcome before technical maturity. The low speed reciprocating nature of many devices combined with the challenging environment require the development of bespoke electrical machines in a direct drive system. This paper describes a research project that is developing a small direct drive wave energy device. The aim is to prove that electrical machines can reliably operate in the marine environment. Heaving buoys are wave energy converters where power is extracted by applying a force to oppose the vertical motion of a floating or submerged prime mover. The force is applied by the power take off which requires provision of an inertial reference, for example a drag plate or the sea bed. Linear direct drive power take off in heaving wave energy converters can suffer from end stop problems, where large uncontrolled oscillations and forces between the prime mover and the inertial reference damage the power take off. For example, over extending either a hydraulic or electric power take off in storm waves off can cause irreconcilable damage. One way of avoiding this is to remove the inertial reference in rough seas. In an IPS buoy the inertial reference is provided by a piston coupled to water entrapped by an open ended cylinder. If the piston leaves the cylinder, it is no longer coupled to the water mass and its inertial reference drastically reduces. In this case the piston can simply ‘follow’ the prime mover oscillation. An IPS buoy therefore presents an excellent device to demonstrate direct drive power take off. In the direct drive demonstrator proposed in this paper, the electrical power take off is integrated with the inertial piston and tube of an IPS buoy. The piston acts as the electrical translator and the cylinder houses the stator coils. A number of design challenges are presented. For example, the piston/translator either needs to be neutrally buoyant, or must be held in position by an external force. Neutral buoyancy imposes constraints on the size and solidity of the translator, whereas the length and radius of the cylinder directly effects the amount of power that can be captured. It is an integrated design problem. A hydrostatic model to size the piston and a linear hydrodynamic model to size the cylinder are presented. The active area of the electric power take off is constrained by the parameters of the piston and cylinder, so design requires integrated hydrostatic, hydrodynamic and electromagnetic modelling. Oscillation results are compared to predictions from commercial software for validation and used to inform the electrical design. The electrical generator will oscillate slowly compared to conventional generators implying the use of some form of magnetic gearing, challenging for mass constrained designs, or reliance on a large amount of rare earth magnetic materials, which has a significant cost implication. A number of electrical machine topologies are investigated in the paper (surface mounted PM machines, Halbach array, and flux concentrated).

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A self-powered and self-sensing wave energy harvester based on a three-rotor motor of axle disk type for sustainable sea

Xia,

Fan,

Zhou

et al. 2024

Energy

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Development and Wave Tank Demonstration of a Fully Controlled Permanent Magnet Drive for a Heaving Wave Energy Converter

Cited by 4 publications

References 45 publications

An Innovative H-Type Flux Switching Permanent Magnet Linear Generator for Thrust Force Enhancement

An Innovative H-Type Flux Switching Permanent Magnet Linear Generator for Thrust Force Enhancement

Design of an integrated generator and heaving buoy

A self-powered and self-sensing wave energy harvester based on a three-rotor motor of axle disk type for sustainable sea

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