This digest proposes the design of a high-efficiency ultra-high-speed motor (UHSM) for fuel-cell air compressors. The UHSM experiences an exponential increase in stator core loss and rotor eddy current loss as the operating frequency increases. These high-frequency losses drastically decrease motor efficiency and affect thermal integrity. This study developed a new amorphous stator with multi-phase winding to overcome these issues. First, an ultra-low loss amorphous metal is used for the stator to reduce the high-frequency core loss. Since the amorphous metal is harder to process into conventional stator geometry, the proposed stator has a separated hollow-cylinder yoke and a fully opened rectangular stator tooth. Second, a multi-phase stator winding is adopted to decrease the magnet eddy current loss by reducing the airgap MMF harmonics.
