Direct Drive Wind Turbines - Wind Power for the World: The Rise of Modern Wind Energy - page 451

machine, but is highly established nowadays with a market share
of 60% in Germany in 2011, although its price ranges over that of
competitors.
Various types of DD concepts emerged since 1990; for example,
the prototype of the Genesys-project, and the concepts by Vensys/
Goldwind, Lagerwey, Zephyros, Mtorres, Leitwind, Hyundai,
Impsa and Siemens. Some manufacturers used the proposals and
experiences from the research team “Windenergie” of the Saarland
University of Applied Sciences, which were developed under
the lead of Professor Friedrich Klinger. The company Vensys is a
start-up of this group.
An important indicator of the concept is the so-called
“external rotorring” that applies permanent magnets to excitate a
synchronous machine and therewith decrease the outside diameter
of the generator (DDPM). In Fig. 19.6 a concept drawing shows
the principle of a gearless wind turbine, as it was planned by
Klinger in 1990.

Figure 19.6 Professor Friedrich Klinger and the concept drawing of the DD

from 1990 (Image: author).

With a sketch like this, Klinger and a group of students and
researchers went on an excursion to north Germany in spring 1990
in order to visit the leading companies producing wind turbines
like Tacke, Husumer shipyard and Enercon in Aurich (Fig. 19.7).