Reduction in Eddy Current Loss of Concentrated Windings in High-power Density IPMSM Using Rectangular Windings

Researches on more electric aircraft (MEA) are actively conducted. It is necessary for realizing MEA to meet aircraft application requirements: high ability, high availability, and high-power density, while aiming to reduce weight and environmental impact. For example, interior permanent magnet synchronous motors (IPMSMs) are expected to be used for aircraft applications of MEA, because IPMSMs can achieve both high-power density and high efficiency at high speed and high torque area compared to other types such as induction motors. In general, IPMSMs with concentrated winding structure are available to utilize limited space effectively. Rectangular windings allow high winding factor and realizing more high-power density motors, whereas eddy current loss in rectangular windings is much higher than that in round windings. In this paper, high-power density concentrated winding IPMSMs that employ rectangular windings are discussed. We have examined three improvements for a reduction of the eddy current loss in the rectangular windings to attain continuous operation with high-power density in this motor. In order to reduce the eddy current loss in the windings situated in front of the rotor, we adopted an asymmetric tooth-tip. Moreover, an adequate groove shape between tooth and stator yoke allows to reduce the eddy current loss in stator yoke side windings. Windings, which have optimized unequal cross-sectional area, offer to reduce whole winding loss. Finally, we present a proposed motor employing the three improvements.