Rotor design for PM generators reflecting the unstable neodymium price

Eriksson, Sandra; Bernhoff, Hans

doi:10.1109/icelmach.2012.6350064

Cited by 47 publications

(40 citation statements)

References 15 publications

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“…A research project has investigated designing a new generator for the 200 kW VAWT, where NdFeB is substituted with ferrite magnets. Results show that very similar electromagnetic characteristics can be achieved [48] only differing slightly in overload behavior [49]. The next step in this project is to build a first ferrite generator prototype based on a developed 12 kW design [50].…”

Section: Research On Generators For Vawtsmentioning

confidence: 99%

A Review of Research on Large Scale Modern Vertical Axis Wind Turbines at Uppsala University

2016

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This paper presents a review of over a decade of research on Vertical Axis Wind Turbines (VAWTs) conducted at Uppsala University. The paper presents, among others, an overview of the 200 kW VAWT located in Falkenberg, Sweden, as well as a description of the work done on the 12 kW prototype VAWT in Marsta, Sweden. Several key aspects have been tested and successfully demonstrated at our two experimental research sites. The effort of the VAWT research has been aimed at developing a robust large scale VAWT technology based on an electrical control system with a direct driven energy converter. This approach allows for a simplification where most or all of the control of the turbines can be managed by the electrical converter system, reducing investment cost and need for maintenance. The concept features an H-rotor that is omnidirectional in regards to wind direction, meaning that it can extract energy from all wind directions without the need for a yaw system. The turbine is connected to a direct driven permanent magnet synchronous generator (PMSG), located at ground level, that is specifically developed to control and extract power from the turbine. The research is ongoing and aims for a multi-megawatt VAWT in the near future.

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Section: Research On Generators For Vawtsmentioning

confidence: 99%

A Review of Research on Large Scale Modern Vertical Axis Wind Turbines at Uppsala University

2016

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“…To investigate the effect of increased top head mass on the tower mass, a relationship between tower mass and top head mass (for a 90m hub height) can be found by fitting a power law curve to the data in [26], (18) Using the structural steel cost from Table III, the tower cost's relationship to top head mass, Ctower (k€) can be approximated by a linear function in the range 400 < mtop < 600 tonnes as, (19) In terms of foundation type, a monopile was assumed in this study. Based on [27] and [28], for a 6MW wind turbine with a 90m hub height in 30m water depth, the relationship of substructure and foundation mass, msf with top head mass can be given as (20) Using the steel cost from Table III (assuming 60% pile and 40% transition piece and outfitting steel), The effect of any increased generator mass on the turbine substructure and foundation cost, Csf (k€) can be approximated by a linear function for 400 < mtop < 600 tonnes as, (21) E. Optimization Design optimization methods generally use an algorithm which take independent variables as input and vary those input to evaluate dependent variables in machine model and hence optimize an objective function (subject to predetermined constraints).…”

Section: Tower and Foundation Costmentioning

confidence: 99%

“…The magnetic properties of the chosen magnet materials are given in [19]. Lumped parameter magnetic circuit models are used to calculate flux per pole.…”

Section: B Electromagnetic Modelmentioning

confidence: 99%

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On the Optimization of Generators for Offshore Direct Drive Wind Turbines

McDonald

Bhuiyan

2017

IEEE Trans. Energy Convers.

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The Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output.1 Abstract-The objective of this paper is to optimize direct drive permanent magnet synchronous generators for offshore direct drive wind turbines in order to reduce the cost of energy. A 6MW wind turbine design is assumed and parametric electromagnetic and structural generator models are introduced for a surface-mounted magnet generator topology (using magnets with high BHmax) and a flux-concentrating variant (using magnets with lower BHmax). These are optimized using a hybrid Genetic Algorithm and Pattern Search process and the results show that the surface-mounted permanent magnet generator produces the lower cost of energy. The choice of objective function is addressed and it is found that a simplified metric incorporating generator cost and losses proxy produces similar designs to a full cost of energy calculation. Further steps to improve the quality of the model include the effect of generator mass on the design and cost of the turbine tower and foundation, which can add €0.4m to the turbine cost. Further optimizations are carried out to show the impacts of magnetic material costs (doubling this leads to a €1.1/MWh increase in cost of energy) and generator diameter limits (increasing the upper limit from 6m to 8m leads to a 0.9% drop in cost of energy) have on the choice of optimum independent variables.Index Terms-Cost of energy, direct drive wind turbine, optimization, permanent magnet generator, structural model, tower and foundation. I. INTRODUCTIONgrowing proportion of offshore wind turbine designs are now based on directly driven permanent magnet synchronous generators. Direct drive machines can offer higher reliability and reduced maintenance cost because of the omission of the gearbox from the drive train [1]. Some of the downsides of these generators include their large size (due to the high torque rating), requirements for large quantities of rare earth permanent magnets and the significant generator structures required to maintain the small air-gap clearance against the large attraction forces between the rotor and the stator [2]. The generator designer needs to deliver a number of performance characteristics including high efficiency, low power losses at part load, high availability, low machine mass, reduced volume and lower material and manufacturing costs. Normally the designers employ some element of optimization to achieve the best balance of these aspects [3].The main purpose of this paper is to examine the process of optimizing large, low speed generators for offshore direct drive wind turbines, exploring the different objective functions that a A. McDonald and N. A. Bhuiyan are with the Institute of Energy and Environment, Department of Electronic and Electri...

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“…Nd 2 Fe 14 B-magnets can be used in the LG. Issues regarding environment, health, and price [28] do however make these rare earth magnets unfit for a sustainable WEC. Ferrite permanent magnets (PMs), with magnetization in the direction of motion, are placed between pole shoes and used in the LG.…”

Section: Introductionmentioning

confidence: 99%

Study of an Altered Magnetic Circuit of a Permanent Magnet Linear Generator for Wave Power

et al. 2017

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The wave energy converter (WEC) studied and developed at Uppsala University in Sweden is a point absorbing buoy connected to a linear generator (LG) on the seabed. Previous studies have improved the sustainability of the generator, changing its magnets from Nd 2 Fe 14 B-magnets to ferrites. In this paper, the magnetic circuit of the linear generator is further studied. Ferrite magnets of two different types (Y30 and Y40) are studied along with different shapes of pole shoes for the system. The finite element method (FEM) simulations in a program called Ace are performed. The results show that a linear generator including both Y30 and Y40 magnets and shortened T-shaped pole shoes can generate a similar magnetic energy in the airgap as a linear generator only containing Y40 magnets and rectangular pole shoes. This shows that the magnetic circuit can be altered, opening up sizes and strengths of magnets for different retailers, and thereby possibly lowering magnet cost and transportation. This work was previously presented as a conference at the European Wave and Tidal Energy Conference (EWTEC) 2017 in Cork, Ireland; this manuscript has been carefully revised and some discussions, on magnet costs for example, have been added to this paper.

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Rotor design for PM generators reflecting the unstable neodymium price

Cited by 47 publications

References 15 publications

A Review of Research on Large Scale Modern Vertical Axis Wind Turbines at Uppsala University

A Review of Research on Large Scale Modern Vertical Axis Wind Turbines at Uppsala University

On the Optimization of Generators for Offshore Direct Drive Wind Turbines

Study of an Altered Magnetic Circuit of a Permanent Magnet Linear Generator for Wave Power

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