Design of a 250kw, Fault-Tolerant PM Generator for the More-Electric Aircraft

*† ‡ § ** †† This paper describes a fault-tolerant permanent magnet machine for use as a direct-drive low-pressure shaft generator for a large civil aircraft engine. The paper is concerned specifically with the design of a 250kW generator for a ‘more-electric’ engine which operates over a speed range of 1050rpm to 3100rpm. The paper describes the issues which must be considered in the selection of the preferred topology, phase number and pole/slot combinations, with particular reference to achieving the desired fault-tolerance and power density. Having established a candidate design using well established design guidelines, the performance of the generator in terms of electrical and thermal behavior is predicted using a range of detailed modeling tools. The importance of several design features such as stator core air cooling ducts and rotor magnet segmentation are illustrated within the context of this design study.