Fractional-slot PM motors for electric power steering systems

This paper deals with some considerations about a PM motor with fractional number of slot per pole per phase, adopted for an electric power steering system. The key requirements of such a system, such as efficiency, torque ripple, fault tolerance, weight and cost, are considered and discussed. The possibility to design the motor in different forms is investigated, introducing some criteria to evaluate the convenience of using non-overlapping winding.