Improving the Thermal Performance of Rotary and Linear Air-Cored Permanent Magnet Machines for Direct Drive Wind and Wave Energy Applications

Air-cored machines offer benefits in terms the elimination of magnetic attraction forces between stator and rotor. With no iron in the stator there is not a good thermal conduction path for heat generated by Joule losses in the stator winding. Results from both models and experimental tests are provided in this paper to investigate different methods of cooling air-cored windings, including natural air-cooling, direct liquid cooling, and the use of heat pipes.