A manufacturing driven design methodology to lightweighting of the structural elements of a permanent magnet electrical machine rotor

It is common practice for electrical machines to be designed with a focus predominantly on the electromagnetic performance. The mechanical design is then subsequently undertaken to meet various mechanical performance criteria, with this finalised design then passed on for manufacture. In many cases, the manufacturing constraints have not been taken fully into consideration during the electromagnetic or more particularly the mechanical design and hence some changes are required to the design to make it manufacturable. This in turn can lead to a non-optimal machine being manufactured. If manufacturing constraints and opportunities are regarded as key quantitative inputs to the design process, not only can these post-design changes be minimised, but benefits of the manufacturing process can be exploited to produce a superior product. This paper proposes a methodology to fully integrate the mechanical design and manufacturing process routes into electrical machine design and illustrates its utility within the context of light-weighting of a permanent magnet rotor for an aerospace electrical machine. Within the proposed methodology, several alternative configurations of the rotor are considered with applicable manufacturing routes identified at the initial stages of design and an analytical design procedure to fulfil the application and performance criteria is developed. Different manufacturing materials and constraints as well as the impact of manufacturing process are identified to be embedded into the design procedures. Finally, the paper demonstrates an application of this methodology together with a discussion of the features which offer promise in achieving economically lighter weight design through integration of manufacturing into the design procedure.