Evaluation of Magnetic Behavior of a Single Pole Pair Fe-Cr-Co-Based Memory Motor Considering Standstill Magnetization

Variable flux memory machines (VFMMs) can have their level of magnet flux density modified by the injection of
$d$
-axis current pulses in the armature windings. The use of Fe-Cr-Co magnets as a source of the magnetic field in these machines is still little explored, even if these magnets present interesting thermal and mechanical properties. In this context, this article explores the validation of a standstill magnetization strategy applied in a non-salient single pole pair Fe-Cr-Co-based VFMM designed for high-speed applications in the transportation electrification field. Due to the absence of a well-defined knee on the second quadrant of the hysteresis loop of the magnet used, the methodology commonly seen in the literature for describing the behavior of the recoil lines defining the working points cannot be directly used. Therefore, by the experimental results obtained from the standstill magnetization of the VFMM studied, a new methodology is developed based on the estimation of the remanence in terms of the excitation field characterizing the internal hysteresis loops of the Fe-Cr-Co. The achieved results are compared with the reference obtained from a HysteresisGraph, which represents a closed and ideal magnetic circuit of measurement. The effects of a stator geometry designed with closed slot wedges in the VFMM and the anisotropy shape are explored for justifying the differences observed.