Airflow control arrangement

1. An airflow control arrangement for a direct-drive wind-turbine, the direct-drive wind-turbine having a generator and an outer rotor free to rotate about an inner stator, the airflow control arrangement comprising:

an outflow fan arranged to draw an exit airflow through an exit duct, wherein the exit duct extends from an interior cavity of the inner stator to an environment that is exterior to the wind-turbine; and

an exit flow arrangement that includes a plurality of hatches, the plurality of hatches including a first hatch for regulating the exit airflow to the environment exterior to the wind turbine and a second hatch for regulating the exit airflow into an interior region of a canopy of the direct-drive wind-turbine.

2. The airflow control arrangement according to claim 1 , wherein the outflow fan draws the exit airflow into the exit duct from a generator cavity through an air-gap between a plurality of magnet poles of the outer rotor and a plurality of windings of the inner stator.

3. The airflow control arrangement according to claim 1 , wherein the exit duct is arranged to extend in an essentially airtight manner through a separating meals arranged to separate the interior cavity from the interior region of the canopy of the wind-turbine.

4. The airflow control arrangement according to claim 1 , comprising a plurality of stator ducts, wherein a stator duct of the plurality of stator ducts extends through the inner stator from a rear cavity of the generator proximate a rear of the generator to a front cavity of the generator proximate a front of the generator, and wherein at least a portion of the exit airflow is drawn by the outflow fan through the stator duct.

5. The airflow control arrangement according to claim 1 , comprising an inflow fan arranged to draw an input airflow into the interior region of the canopy of the wind-turbine.

6. The airflow control arrangement according to claim 1 , wherein the exit outflow arrangement comprises a three-way hatch for regulating the exit airflow to the environment that is exterior to the wind-turbine and/or into the interior of the canopy.

7. The airflow control arrangement according to claim 1 , comprising a plurality of temperature sensors for measuring a temperature of the interior region of the canopy and/or in the generator and/or at a plurality of magnet poles of a generator field and/or at a plurality of windings of the generator armature; and a plurality of humidity sensors for measuring humidity of a region exterior to the canopy at the canopy exterior and/or in an interior cavity of the inner stator.

8. The airflow control arrangement according to claim 1 , comprising a control unit configured to control at least the exit outflow arrangement and/or the outflow fan and/or an inflow fan on the basis of measurements provided by a sensor.

9. The airflow control arrangement according to claim 1 , comprising a filter arrangement and/or a mist eliminator arranged at an inflow fan, wherein the filter arrangement is configured to filter airborne particles from the air, and wherein the mist eliminator is realized to remove humidity from the air.

10. The airflow control arrangement according claim 1 , comprising a plurality of stator ducts extending from the interior region of the canopy to a front cavity of the generator proximate a front of the generator.

11. The airflow control arrangement according to claim 1 , comprising a thermally insulating layer between the exit duct and the interior region of the canopy.

12. A method of controlling an airflow in a direct-drive wind-turbine with a generator, the direct-drive wind-turbine including an outer rotor free to rotate with an inner stator, the method comprising:

driving an outflow fan to draw an exit airflow through an exit duct, wherein the exit duct extends from an interior cavity of the stator to an environment that is exterior to the wind-turbine;

actuating a plurality of hatches of an exit outflow arrangement, the plurality of hatches including a first hatch for regulating the exit airflow to the environment exterior to the wind turbine and a second hatch for regulating the exit airflow into an interior region of a canopy of the direct-drive wind-turbine.

13. The method according to claim 12 , comprising the steps of:

measuring a temperature at a canopy exterior of the canopy and/or in a generator interior region and/or at a plurality of magnet poles of a generator field of the generator and/or at a plurality of windings of a generator armature of the generator;

measuring a relative humidity at the canopy exterior and/or in the generator front cavity and/or in the interior of the canopy interior and/or in the interior or cavity of the stator; and

controlling the exit outflow arrangement on the basis of the measurements using control signals.

14. The method according to claim 13 , comprising the steps of:

actuating the exit outflow arrangement to guide essentially the entire exit airflow back into the interior region of the canopy; and

driving the outflow fan to heat and/or re-circulate the exit airflow until a a desired temperature is reached in a specific region of the wind-turbine.