This　paper　develops　a　model　to　compute　the　rotor　permanents　magnets,　the　structure　which　is　usual　used　in　the　generator.　To　carry　out　such　a　design,　the　company　usually　employs　finite　element　analysis　software　even　if　it　is　time　consuming.　Other　designers　employ　FEM　and　BEM　to　evaluate　the　unknown　air-gap　permeance.　We　describe　a　approach　based　on　the　coupling　of　an　ordinary　differential　equation　(ODE)　and　arbitrary　Lagrangian-Eulerian　(ALE)　for　the　performance　analysis　of　the　generator.　Finite　element　method　can　be　used　to　calculate　geometry　effect,　the　air-gap　distance,　to　the　magnetic　flux　density　and　the　power　flow　which　is　analyzed.　©　2011　IEEE.