This paper presents a thermal fluid analysis on the air cooling of a permanent magnet electric motor with a centrifugal impeller. A numerical model is developed for the heat transfer and fluid flow process. The flow rates of the cooling air are also experimentally measured. The agreement between the numerical model prediction and experimental data is reasonably good. Detailed structures of the cooling flow are presented. Convection heat transfer on the surface of the armature is quantified. Comments on the application of the motor architecture are given. Design modifications are proposed for performance improvements. (C) 2009 Elsevier Ltd. All rights reserved.