Efficiency map simulations for an interior PM motor with experimental comparison and investigation of magnet size reduction

Reduction of permanent magnet materials in electric machines is of interest to many machine manufacturers and designers as cost of rare-earth materials is of increasing concern. The impact of changing a machine design parameter, such as the shape of the magnets, may have consequences such as a reduction in efficiency, or introduce a change in torque quality. In this paper, an efficiency map computation is compared with measurements for a permanent magnet synchronous machine, including the complete torque-speed operating region. The validated simulation model led to an investigation of reducing the permanent magnet size where 20% of magnet size reduction was achieved. The impact of the magnet size reduction on the efficiency and machine performance was quantified, and design changes were simulated which maintained the desired efficiency over the operating range.