Comparison of PMAC Machines for Starter-Generator Application in a Series Hybrid-Electric Bus

This paper presents a comparative study of outer rotor PMAC machine candidates for starter-generator application in hybrid bus with series power train configuration. PMAC machines with interior and surface mount permanent magnets are considered and compared, although a complete analysis is only carried out for the SPM. Different design aspects such as concentrated versus distributed windings as well as interior and exterior rotor structures are evaluated. Different slot numbers per pole per phase configurations for concentrated winding PMAC machines are also examined. Comparison and evaluation of the machines is based on their performance which included evaluation of winding and iron losses, magnet losses, and maximum torque capability as well as the size and weight of the machines.