Additive Manufacturing of a Soft Magnetic Rotor Active Part and Shaft for a Permanent Magnet Synchronous Machine

This paper describes the design, the additive manufacturing process and the testing of a soft magnetic rotor active part and shaft region for a permanent magnet synchronous machine (PMSM). In a first step, the best possible ferromagnetic material was identified by investigating additively processed ferro-silicon and ferro-cobalt alloys which achieve both mechanic and electromagnetic requirements for PMSM. After this, a surface-mounted PMSM was chosen to serve as reference. Both the rotor active part as well as the shaft were made of a ferro-silicon alloy and produced generatively by using laser beam melting (LBM). To underline the high potential of additive manufacturing technologies in the field of electric machinery design, a supplemental feature was added to the rotor which only could be realized expediently due to the rapid development of metal-additive manufacturing. To be more specific, supplementary slots were added underneath the magnets, which-one per pole -contain short-circuited copper wires for increased self-sensing performance due to increased magnetic anisotropy. After assembling the additively manufactured rotor shafts into aconventionally laminated stator, the general functionality of the machine as well as the influence of the additional rotor coils were tested and compared with each other.