Design criteria of axial flux PM machines for direct drive wind energy generation

This paper deals with some design criteria of axial flux permanent magnet synchronous machines, wound with concentrated coils: in particular, the application to direct drive wind power generation is considered. The structure and the features of these machines are illustrated, the main sizing equations are deduced, and some guidelines for the design are presented, also by means of a sensitivity analysis, performed by taking as an example the design of a small rating 3-phase generator (50 kW, 70 rpm).