State of the art of additively manufactured electromagnetic materials for topology optimized electrical machines

Metal additive manufacturing (AM) technology is maturing. Although currently slower and less reliable than traditional production methods, AM systems shine when producing parts with unconventional topologies or in small quantities. Like countless other research communities, the electrical machine (EM) research community has shifted considerable efforts towards integrating AM systems into the EM production cycle to implement more powerful and efficient topology optimized (TO) next-generation EMs. In this paper, the state-of-the-art printing of soft magnetic, hard magnetic, and electrically conductive materials was investigated to evaluate the maturity of each material type for integration into EM construction. The highest maturity was identified for AM pure copper, showing characteristics equivalent to commercial high purity copper. In contrast, AM permanent magnets were the least mature: suffering from low power density and limited magnetization capacities. Printed soft magnetic steels were characterized as halfway in-between: on one side showing equivalent DC magnetic properties to conventional non-oriented steels, but on the other – suffering from high eddy current losses in AC applications. Based on the study's findings, it would appear that the emergence of additively manufactured EMs is only a matter of time. We predict a dramatic increase in the printing of prototype TO components within the next few years, focusing most likely on TO machine windings, heat exchangers, and synchronous rotors.