A HIGH SPEED FAULT TOLERANT TRANSVERSE FLUX ALTERNATOR FOR AEROSPACE

This paper presents the design methodology of a transverse flux alternator for a high speed aerospace application. A four single phase permanent magnet (PM) transverse flux machine is proposed to achieve a certain power level at low speed (400 rpm) under the short circuit fault current constraints at higher speeds (15000 rpm). Due to a relatively small volume envelope of the proposed machine, a 3D parametric machine geometry was optimised within the given space by using several finite element (FE) optimisation approaches including genetic algorithm (GA) and design of experiment (DoE). The parametric machine geometry was further investigated to reduce the cogging torque and mutual flux linkages between the separate phases and also the manufacturing limitations have been accounted to build an alternator with soft magnetic composites (SMC). It is shown that the proposed machine achieves the performance specifications of the fault tolerant aerospace application but the proposed design comes with different averaged power levels at the phase outputs due to dissimilarity between mutual inductances, which are usually unavoidable in the axially positioned stators topologies with relatively very low synchronous phase reactances.