Design of a wound field synchronous machine for electric vehicle traction with brushless capacitive field excitation

This paper describes the modeling, optimization, mechanical design, and experimental characterization of a high power density wound field synchronous machine (WFSM) for electric vehicle traction applications. The WFSM is designed for brushless rotor field excitation using an axial flux hydrodynamic capacitive power coupler (CPC). A flexible design environment is described which was used for large scale multi-objective optimization. A prototype WFSM, spray cooled with automatic transmission fluid (ATF), with an 80 kW (peak) output at a base speed of 4,000 RPM has been tested. The prototyped WFSM achieves peak volumetric and specific torque and power densities of 17.22 Nm/l, 4.69 Nm/kg, 7.19 kW/l, and 1.95 kW/kg.