A Baseline Thermal Model for Liquid-Cooled Multi-Megawatt Scale Direct-Drive Permanent Magnet Wind Turbine Generators

This paper presents a thermal model of a liquid cooled multi-megawatt scale direct-drive (DD) permanent magnet (PM) wind turbine generator (WTG). A spiral water jacket (WJ) is positioned between the stator yoke and stator frame and circulates coolant via an external heat exchanger (HE) located on the outside of the nacelle. A lumped parameter thermal network (LPTN) model of the generator is developed in combination with analytical approaches for estimating the WJ and HE performance. It is shown that the performance of the WJ is limited due to low thermal conductivity within the stator and that a more intrusive cooling strategy is necessary if armature current loading is to be increased beyond typical values.