Design of a Spoke-Type Ferrite Magnet Generator for a Hybrid Electric Vehicle Application

This paper presents a comprehensive analysis of different spoke-type magnet motor-generators used in hybrid electric vehicles. Different techniques are investigated to increase the machines' maximum torque per ampere ratio and efficiency while reducing the torque ripple. The machines use embedded ferrite magnets and 48/8 stator winding topology. Designs with various magnet shapes with and without non-magnetic rotor support are investigated. Demagnetization analysis for the ferrite magnets at low temperatures is performed. Various ferrite materials are used, and different techniques are utilized to mitigate the irreversible demagnetization. Moreover, structural analysis is carried out for two different motor-generators at their maximum speeds.