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FEM simulations and experiments of different loading conditions for a 12 kW direct driven PM synchronous generator for wind power
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
2009 (English)In: International Journal of Emerging Electric Power Systems, ISSN 1553-779X, Vol. 10, no 1, 3- p.Article in journal (Refereed) Published
Abstract [en]

Results from experiments on a direct driven permanent magnet synchronous generator are presented. Dynamic simulations have been performed using the finite element method in order to study the generator. The simulations are performed by using an electromagnetic model, which is described by a combined field and circuit equation model and is solved in a finite element environment. The stator winding of the generator consists of circular cables and the rotor has surface-mounted, arched, permanent magnets. A complete experimental setup has been used consisting of a motor, a frequency converter, a gearbox and electrical loads. The generator is connected to a purely resistive load. Measurements have been performed for different rotational speeds and different loads. Furthermore, the generator has been studied for the realistic wind turbine loading conditions for operation at the optimum tip speed ratio. The variable speed operation in a wind turbine is evaluated and discussed. The agreement between experimental results and simulations based on finite element calculations is high, indicating precise simulations. The measurement errors are calculated and discussed. Furthermore, other sources of error are suggested and discussed that could explain the differences between the simulations and the measured data. 2009 The Berkeley Electronic Press. All rights reserved.

Place, publisher, year, edition, pages
2009. Vol. 10, no 1, 3- p.
Keyword [en]
Electric generators, Engines, Experiments, Finite element method, Magnetic devices, Measurement errors, Permanent magnets, Steel structures, Synchronous generators, Wind power, Wind turbines
National Category
Engineering and Technology
URN: urn:nbn:se:uu:diva-97456DOI: 10.2202/1553-779X.1958OAI: oai:DiVA.org:uu-97456DiVA: diva2:172413

Compilation and indexing terms, Copyright 2009 Elsevier Inc. 20091712047064 Circuit equations Direct-driven Dynamic simulations Electrical loads Electromagnetic models Experimental set-up FEM simulations Finite element calculations Finite elements Generator Loading conditions Measured datum Permanent magnet synchronous generators Precise simulations Purely resistive loads Rotational speed Simulations Stator windings Synchronous Tip-speed ratios Variable speed operations Vertical axis wind turbine Wind turbine loadings

Available from: 2008-09-05 Created: 2008-09-05 Last updated: 2014-01-17Bibliographically approved
In thesis
1. Direct Driven Generators for Vertical Axis Wind Turbines
Open this publication in new window or tab >>Direct Driven Generators for Vertical Axis Wind Turbines
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Wind power is a renewable energy source that is increasingly used all over the world. Most wind turbines have a horizontal axis of rotation but a few have a vertical axis of rotation. The concept presented in this thesis is a straight-bladed vertical axis wind turbine with a direct driven cable-wound permanent magnet synchronous generator. A comparison of the two different types of wind turbines, vertical axis wind turbines and horizontal axis wind turbines, have been performed considering several different aspects. However, the main focus in this thesis is on the generator.

Several generators have been modelled with a combined field and circuit model, which has been solved by using the finite element method. A 12 kW generator has been designed, which has a high overall efficiency and a high overload capability. The generator has been constructed at the department and was tested in the laboratory before being mounted in a vertical axis wind turbine. Results from experiments correspond well with results from simulations. The generator has been tested for different loading conditions and the harmonic content of the voltage has been analysed. A 12 kW vertical axis wind turbine was completed and tests have been performed. The results are encouraging and further studies on the prototype will be performed in the future.

The simulation method has been used to study electromagnetic losses in several generators. The comparison showed that the average losses should be considered when a variable speed generator for wind power is designed and it concluded that the design optimization process becomes a compromise between lowering the electromagnetic losses and having high overload capability.

When constructing a wind turbine, it is important to consider vibrations in the structure. Torsional vibrations in the drive shaft connecting the turbine to the rotor of the generator have been studied. It is shown that a direct driven generator is to prefer over an induction generator with a gearbox when torsional vibrations are concerned.

This thesis is based on eight papers all concerning vertical axis wind turbines with three of them focusing on the generator.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2008. 88 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 547
synchronous generator, wind power, vertical axis wind turbine, simulations, experiments, finite element method
National Category
Other Engineering and Technologies
urn:nbn:se:uu:diva-9210 (URN)978-91-554-7264-1 (ISBN)
Public defence
2008-09-26, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Available from: 2008-09-05 Created: 2008-09-05 Last updated: 2010-04-23Bibliographically approved

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