A Compensated Mini-Permeameter for Localized Magnetic Loss Measurements on Magnetic Laminations

Accurate magnetic loss characterization in permeameter-based systems is strongly affected by the magnetomotive force (MMF) drop in the flux-closing yokes, particularly in compact geometries where only a limited portion of the specimen is magnetized. In this work, a compensated mini-permeameter capable of magnetizing the central 60 mm region of a single Epstein strip is presented. MMF compensation is implemented through an auxiliary compensation winding and a feedback control scheme, enabling accurate determination of the magnetic field from the magnetizing current. The system is experimentally validated by comparison with local tangential H-coil measurements on a non-grain-oriented electrical steel with a thickness of 0.35 mm. Magnetic loss and hysteresis loops measurements performed at 50 Hz show that compensation effectively reduces systematic loss overestimation, yielding good agreement with the reference measurements. The proposed approach provides a compact and reliable solution for localized magnetic loss characterisation and can be readily extended to standard and non-standard single-sheet testers.