Volume 3, issue 1 | Copyright
Wind Energ. Sci., 3, 97-105, 2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research articles 14 Mar 2018

Research articles | 14 Mar 2018

Friction torque of wind-turbine pitch bearings – comparison of experimental results with available models

Matthias Stammler1, Fabian Schwack2, Norbert Bader2, Andreas Reuter1, and Gerhard Poll2 Matthias Stammler et al.
  • 1Fraunhofer IWES, Appelstraße 9A, 30167 Hanover, Germany
  • 2IMKT, Leibniz Universität Hannover, Welfengarten 1a, 30167 Hanover, Germany

Abstract. Pitch bearings of wind turbines are large, grease-lubricated rolling bearings that connect the rotor blades with the rotor hub. They are used to turn the rotor blades to control the power output and/or structural loads of the turbine. Common actuators turning the blades are hydraulic cylinders or electrical motor–gearbox combinations. In order to design pitch actuator systems that are able to turn the blades reliably without imposing an excessive power demand, it is necessary to predict the friction torque of pitch bearings for different operating conditions. In this paper, the results of torque measurements under load are presented and compared to results obtained using different calculation models. The results of this comparison indicate the various sources of friction that should be taken into account for a reliable calculation model.

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Short summary
Modern wind turbines all share the ability to turn (pitch) the blades around their main axis. By pitching the blades, the aerodynamic forces created by the blades are controlled. Rolling bearings, consisting of two steel rings and balls that roll on raceways between them, are used to allow pitching. To design pitch drives, it is necessary to know the losses within the bearings. This article describes how such losses have been measured and compares them with calculation models.
Modern wind turbines all share the ability to turn (pitch) the blades around their main axis. By...