Magnetic detector bands for interior 3D-analyses of laminated machine cores

Abstract

The physical state of laminated soft magnetic machine cores has high technical and economical relevance, in particular if advanced materials are involved, as in the case of transformer cores. Experimental analyses tend to be restricted to core surface regions due to the high expenditure of interior arrangements of sensors. Further, the latter cause inter-laminar spaces, as a reason of artefacts. The paper presents a completely novel sensor concept that avoids the above problems. A magnetic detection band of e.g. 1 m length consists of different kinds of sensors. They are arranged on a substrate foil by combined 2D/3D-printing, the total band thickness being below 100 $\mu$ m. Using the ends as handles, the band is located through the core. Electric connection sockets to electronics remain outside, thus avoiding increased inter-laminar spacing. They also allow for later failure diagnostics, by permanently arranged bands. Sensors concern local distributions of magnetic flux, losses, temperature, strains and vibrations. Manufacturing is aimed on versatile low-cost products. This paper describes procedures that are focused on flux sensors, in particular for in-plane flux that represents the most complex sensor type. For the first time, it enables interior measurements in non-destructive ways.