High temperature superconducting (HTS) generators are being considered for large offshore direct-drive (DD) wind turbines as they are expected to be lightweight and compact. However, short circuit torques of an HTS generator with integral-slot distributed windings (ISDWs) are too high for wind turbine constructions, mainly due to the large magnetic air gap. Fractional-slot concentrated windings (FSCWs) can be considered to address this issue since their high leakage inductance can limit short circuit currents and torques. Unlike ISDWs, FSCWs produce great contents of space harmonics that induce excessive losses in rotor components. Multi-layer and stator-shifting windings have been proposed to effectively reduce such losses. Based on a conventional 12-slot 10-pole configuration, this paper evaluates the effects of multi-layer and stator-shifting FSCWs on torque production and loss reduction in a 10 MW DD HTS generator. The examined losses include eddy current losses in the rotor shields and AC losses in the HTS field winding. This paper also checks if these FSCW schemes maintain the advantage of achieving a low short circuit torque. The results show that a 6-phase stator-shifting winding is the best choice for applying FSCWs to HTS generators.
Bibliographical noteGreen Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care
Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.
- AC loss
- eddy current loss
- fractional-slot winding
- stator shifting
- superconducting generator
- wind turbine