Rotational Core Loss Magnetizer: Design and Measurements

Abstract

Rotational core loss data improve the accuracy of estimating electric machine core losses. The losses are measured using magnetizing yokes, which generate a rotating field. The accuracy of the measured losses is dependent on the uniform distribution of the fields for all the flux-density levels and magnetization directions in an isotropic sample in simulations. Additionally, the field distribution patterns should be the same for all the flux-density vector directions. The measurement area where the field sensors are placed should be large enough for better representation of magnetic material properties. The design should also suppress the z-component of the magnetic field and the leakage flux above the sample. A two-dimensional magnetizing yoke design with a sample measurement area of 65 mm × 65 mm on a 136 mm diameter sample is proposed to meet these requirements. The design was prototyped, and both pulsating and rotational core losses of a 0.36-mm-thick “M-19” nonoriented electrical steel were measured at a range of flux densities and frequencies.