Fault tolerant design of fractional slot winding permanent magnet aerospace actuator

This paper introduces a particular permanent magnet motor (PMM) design methodology, considering advanced magnetic material characteristics, for aerospace actuator applications. In this class of problems, increased electromagnetic power density, fault tolerance, and high-temperature withstand properties are of major importance, and favored single-layer (SL) and double-layer (DL) fractional slot concentrated winding (FSCW) optimal topologies with different motor segmentation strategies have been compared. Under such strict nature of specifications, both operational and spatial, the implementation of advanced magnetic materials, particularly Vacoflux50 cobalt iron laminations and NMX-S43SH neodymium PMs, offer great services. The optimization methodology introduced is based on composite cost and penalty functions involving performance, efficiency, reliability, weight, and thermal criteria for multioperational behavior under normal and temporary overload conditions. An appropriate particle swarm optimization algorithm ensures fast convergence of the optimization variables. The resulting optimal SL and DL FSCW PMM configurations present certain complementary advantages, while the former one offering greater efficiency, thermal robustness, and physical segregation of the two motor parts is favored for this class of applications. Finally, the proposed motor configuration has been validated through measurements on a manufactured prototype.