Dissertation: Technical improvements of Windside wind turbine systems

Posted on 13/08/15.

(Kuva/Photo/Bild: Flickrcc)

The problems encountered with battery charging by wind turbines are that the charging is poor in both low and high wind speeds. The main objective of Bertil Brännbacka’s dissertation is to find methods of improving the charging of batteries at low and high wind speeds by developing auxiliary devices using original components.

The approach was to study the wind turbines in real wind conditions. Two different sizes of Windside wind turbines were investigated. Field data was collected and analyzed. Also, an analytical model was used in the development of the hollow shaft. The prototype shaft was checked by hammer shock test and modal analysis. Furthermore, simulation studies were used to develop the step-up converter and to show the operation of the star delta switch.

– Two novel techniques developed in this work are an automatic reversible star-delta switch, and a hollow shaft. The benefits of the developed items are manyfold.

They can be utilized in applications where small vertical-axis wind turbines are used. The use of automatic reversible star-delta switch increases the annual energy yield of the small turbines by 9 % and the use of 24 V battery bank instead of 12 V by 7 %. The hollow shaft increases the usability of the type wind turbines examined. The developed hollow shaft reduces the overall weight and raw materials used.

Public defence

The public examination of DI Bertil Brännbacka’s doctoral dissertation ”Technical improvements of Windside wind turbine systems” will be on Thursday 20 August at 12 o´clock in auditorium Kurtén (Tervahovi). Professor Jorma Kyyrä (Aalto yliopisto) will act as opponent and Professor Timo Vekara as a custos.

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