Comparison of in-wheel permanent magnet motors for electric traction

This paper undertakes a comparative study between two different in-wheel Surface Mounted Permanent Magnet motors with Fractional Slot Concentrated Winding configurations designed for a light electric vehicle application. For the design of both motors two different approaches are followed, regarding the winding configuration and the relative dimensions of the motor, i.e. axial length and air-gap diameter, and additionally two alternative strategies are adopted concerning the selection of the reference operational point. The first motor comprises a double layer concentrated winding with all teeth wound while is slightly over-dimensioned increasing efficiency during overload operation. A single layer concentrated winding with alternate teeth wound and unequal teeth distribution is adopted for the second motor dimensioned in terms of weight minimization considering the nominal load operation. For the optimization of the first alternative, Taguchi´s method is utilized, while for the latter one a Strength Pareto Evolutionary Algorithm variant is developed. Both performances are validated by examining manufactured prototypes under real conditions.