Direct-drive wind generators

Stephan Jöckel's PhD Thesis:

Calculation of Different Generator Systems for Wind Turbines with Particular Reference to Low-Speed Permanent-Magnet Machines
Shaker Verlag, May 2003, Aachen / Germany
ISBN: 978-3-8322-1512-5

You can buy the thesis from the following web site:
Shaker Verlag GmbH

Papers presented by Stephan Jöckel on several conferences:

Jöckel, S.:
Direct Drive must not be Heavy – the New VENSYS 90 / 100 Gearless Wind Turbines in the 2.5 MW Class
2008 European Wind Energy Conference, 31 March - 3 April 2008, Brussels / Belgium

Jöckel, S.; Rinck, J.; Herrmann, A.:
High Energy Production Plus Built-In Reliability - the new VENSYS 70 / 77 Gearless Wind Turbines in the 1.5 MW Class
2006 European Wind Energy Conference, 27 February - 2 March 2006, Athens / Greece

Jöckel, S.; Klinger, F.; Balzert, S.; Rinck, J.:
VENSYS 62 - the Next Generation of Gearless Turbines Goes into Production.
2003 European Wind Energy Conference, 16 - 19 June 2003, Madrid / Spain

Jöckel, S.; Hagenkort, B.; Hartkopf, T.; Ruckh, M.; Schneider, H.:
Direct-Drive Synchronous Generator System for Offshore Wind Farms with Active Drive-Train Damping by Blade Pitching.
2001 European Wind Energy Conference, 2nd-6th July 2001, Copenhagen/Denmark

Henschel, M.; Datta, R.; Hartkopf, T.; Jöckel, S.:
Reliable and Efficient Generator Systems for Offshore Wind Farms with d.c. Wind Farm Grid and d.c. Cable Connection to the Shore.
2001 European Wind Energy Conference, 2nd-6th July 2001, Copenhagen/Denmark

Schneider, H.; Jöckel, S.; Hagenkort, B.; Henschel, M.; Hartkopf, T.:
Cost and Performance of Direct Drive Generator Systems.
DEWEK ‘2000, Wilhelmshaven/Germany, Jun. 07 - 08, Proc. pp 445-448, (2000).

Epskamp, T.; Hagenkort, B.; Hartkopf, T.; Jöckel, S.:
No Gearing, no Converter – Assessing the Idea of Highly Reliable Permanent-magnet Induction Generators.
1999 European Wind Energy Conference, 1.-5. March 1999, Nice/France Proc. pp 813-816 (1999)

Hagenkort, B.; Hartkopf, T.; Jöckel, S.:
Der permanenterregte Asynchrongenerator – Funktion, Effizienz, Kosten.
Deutsche Windenergiekonferenz DEWEK 98, October 1998, Wilhelmshaven/Germany, Proc. pp 345-348, (1998)

Hartkopf, T.; Hofmann, M.; Jöckel, S.:
Direct-Drive Generators for Megawatt Wind Turbines.
1997 European Wind Energy Conference, Oct. 06 – 09, 1997, Dublin/ Ireland, Proc. pp 668-671 (1997)

Hagenkort, B.; Mutschler, P.; Jöckel, S.:
Control Method for Variable-Speed Stall Controlled Wind Turbines.
EWEC`97, Dublin / Ireland, Oct. 06 - 09, Proc. pp 542 – 545, (1997).

Jöckel, S.:
Gearless Wind Energy Converters with Permanent-magnet Generators - an Option for the Future?
1996 European Union Wind Energy Conference, May 1996, Göteborg/Sweden, Proc. pp 414-417 (1996)