Surface Eddy Current Suppression on Additively Manufactured Solid Rotor Active Parts

This paper describes the development process, 3D finite element analysis, and resulting design guidelines for reducing eddy current effects on solid rotor surfaces of electrical machines considering the three-dimensional freedom when designing parts that are suitable for additive manufacturing technologies. Today’s metal additive manufacturing technologies allow the processing of soft magnetic ferrosilicon alloys, which results in solid, non-laminated rotor active parts. With respect to permanent magnet rotors with buried magnets as in the present paper, it is necessary to groove the rotor surface in various manners to suppress eddy current effects. In a first step, a 3D finite element abstracted model, which optimally represents the rotor surface eddy current effects caused by higher spatial harmonics in a permanent magnet synchronous machine, is presented and numerically and analytically examined to find and describe an optimal rotor grooving method, in order to reduce eddy current losses and to derive specific design guidelines. In a second step, a test bench design is presented and numerically investigated in preparation for a validation of the theoretical results.