An optimized bi-directional, wide speed range electric starter-generator for aerospace application

This paper will describe a high speed motor-drive system for an aircraft starter-generator. A permanent magnet electrical machine is designed to have minimal rotor losses and a novel cooling system for the stator. An inner stator sleeve is adopted allow for a flooded stator whilst minimizing rotor windage loss. Different slot-pole combinations are compared in view of attaining an optimal combination that provides minimum losses whilst satisfying the electromagnetic, mechanical and thermal constrains. A three-level converter structure is adopted after a comparative study with a two-level structure for different operating regimes. The performance of the complete drive system will be presented through simulation results.