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No-load core loss prediction of PM generator at low electrical frequency
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.
2012 (English)In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 43, 389-392 p.Article in journal (Refereed) Published
Abstract [en]

A method for measurement of frequency dependent electromagnetic core loss of a permanent magnet generator is presented. Core loss of a PM generator is measured at electrical frequencies ranging from 4 to 14 Hz. Core loss in the same interval is simulated using the finite element method and frequency domain loss separation. The specific loss is both extrapolated from specific loss at 50 Hz and measured directly at 4, 8, 12 and 16 Hz. Core loss simulations based on extrapolated specific loss are 38–53% smaller than measured loss. Core loss simulations based on specific loss measured at 4, 8, 12 and 16 Hz are 19–23% smaller than measured loss.

Place, publisher, year, edition, pages
2012. Vol. 43, 389-392 p.
Keyword [en]
Core loss Variable speed PM generator Cable wound generator Loss separation
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Science of Electricity
Identifiers
URN: urn:nbn:se:uu:diva-190099DOI: 10.1016/j.renene.2011.12.002ISI: 000301311500042OAI: oai:DiVA.org:uu-190099DiVA: diva2:583012
Available from: 2013-01-07 Created: 2013-01-07 Last updated: 2017-12-06Bibliographically approved
In thesis
1. A Generator Perspective on Vertical Axis Wind Turbines
Open this publication in new window or tab >>A Generator Perspective on Vertical Axis Wind Turbines
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The wind energy conversion system considered in this thesis is based on a vertical axis wind turbine with a cable wound direct drive PM generator. Diode rectifiers are used to connect several such units to a single DC-bus and a single inverter controls the power flow from the DC-bus to a utility grid. This work considers the described system from a generator perspective i.e. the turbine is primarily seen as a torque and the inverter is seen as a controlled load.

A 12 kW VAWT prototype with a single turbine has been constructed within the project. The power coefficient of this turbine has been measured when the turbine is operated at various tip speed ratios. This measurement determines both how much energy the turbine can convert in a given wind and at what speed the turbine should be operated in order to maximise the energy capture. The turbine torque variation during the revolution of the turbine has also been studied.

A PM generator prototype has been constructed in order to study power loss in the stator core at low electrical frequencies. Heat exchange between the stator and the air-gap between the stator and the rotor has been studied. Heat exchange between the stator and the air-gap is increased by turbulence caused by the rotor. The generator was also used in a demonstration of a DC-grid where two diode rectified PM generators supplied power to a single DC load.  An initial study of an inverter suitable for grid connection of the 12 kW PM generator has been performed.

Several turbine control strategies are evaluated in simulations. The control strategies only require the parameter "turbine speed" to determine the optimal system load.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. 80 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1034
Keyword
VAWT, PM generator, Wind power, Stator core loss
National Category
Energy Systems
Identifiers
urn:nbn:se:uu:diva-197855 (URN)978-91-554-8642-6 (ISBN)
Public defence
2013-05-22, Siegbahnsalen, Lägerhyddsvägen 1, Uppsala, 09:00 (English)
Opponent
Supervisors
Available from: 2013-04-25 Created: 2013-04-05 Last updated: 2013-08-30Bibliographically approved

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Bülow, FredrikEriksson, SandraBernhoff, Hans

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