Research on Electromagnetic and Thermal Issue of High-Efficiency and High-Power-Density Outer-Rotor Motor

The permanent-magnet synchronous motor (PMSM) with high efficiency and high power density is now attracting more and more attention, which could be largely used in occasions supplied by limited energy and restricted by weight or capacity, for example, the electric vehicles and the solar unmanned aerial vehicles. In this paper, the electromagnetic and thermal issue of a PMSM with high efficiency and high power density has been researched. We comparatively analyzed the efficiency and the power density characteristics of the outer-rotor PMSM. The influence of electromagnetic parameters on efficiency and power density has been analyzed. Through researching the Halbach array, we got the maximum output torque and the minimum core loss. Because of the inner stator, the heat generated by the winding has much trouble to dissipate. The thermal-transfer structure based on the heat pipe has been proposed, which could decrease the temperature of windings by more than 180 °C shown by finite-element analysis results. Finally, the prototype motor has been made, and the experimental results are consistent with the analysis, which verified the correctness of the theory.