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

Accurate characterization of magnetic losses in permeameter-based systems is essential for reliable evaluation of magnetic materials. However, the magnetomotive force (MMF) drop in the flux-closing yokes can significantly affect the measurements, particularly in compact geometries where only a limited portion of the specimen is magnetized, leading to systematic overestimation of the losses. This paper presents a compensated mini-permeameter in which the MMF drop in the yokes is counteracted by an auxiliary winding driven by a feedback control scheme. The proposed approach enables the accurate determination of the magnetic field in the magnetized region directly from the magnetizing current. Experimental validation is performed through comparison with local tangential H-coil measurements on 0.35-mm-thick non-grain-oriented and 0.29-mm-thick grain-oriented laminations. Magnetic loss and hysteresis loop measurements at 50 Hz demonstrate that the compensation effectively mitigates systematic loss overestimation and enables close agreement with the reference method for both NGO and GO laminations. The proposed technique provides a compact and robust solution for localized magnetic loss characterization and can be extended to both standard and non-standard single-sheet testers.