Efficiency Comparison of In-wheel PM Motors for Bus Propulsion

In–wheel motors are promising candidates for the propulsion of electric vehicles. Nevertheless, their electromagnetic design and in particular the efficiency evaluation cannot rely on established procedures because of their unconventional configuration. On the other hand, the use of FEM transient codes to evaluate the most problematic loss components (i.e., iron and PM eddy current losses) is generally expensive and time-consuming. The methodology presented in the paper is aimed to overcome such difficulties by means of a suitable elaboration of the results of a sequence of magnetostatic FEM analyses, an adequate accuracy for the design purpose being assured. The methodology can apply to different motor configurations, allowing the comparison from the point of view of the efficiency.