DESIGN OF WOUND FIELD SYNCHRONOUS MACHINES AND HYBRID EXCITATION SYNCHRONOUS MACHINES FOR ELECTRIC VEHICLE TRACTION WITH BRUSHLESS CAPACITIVE FIELD EXCITATION

The focus of this dissertation is to describe the electromagnetic modeling and optimization, mechanical modeling, thermal simulation and experimental characterization of two prototype permanent magnet-free high power density wound eld synchronous machines (WFSMs) and one prototype of permanent magnet-wound eld hybrid excitation synchronous machine (HESM) for electric and hybrid-electric vehicle traction applications. The WFSMs and HESM are designed for brushless rotor eld excitation using an axial ux hydrodynamic capacitive power coupler (CPC) but can also be operated with a brush and slip rings excitation system. A exible design environment has been developed for large scale multi-objective optimization of the machines, particularly focusing on the use of a static electro-magnetic solver, FEMM, and the extension of the software routines to reconstruct the transient behavior of rotating electrical machines. The prototypes are designed to operate with a spray cooling system with automatic transmission uid (ATF Dexron VI) in order to reach power densities comparable to the commercial permanent magnet synchronous machines (PMSMs) for similar applications. The spray cooling system was simulated with a commercial software (MotorCAD) and the modeling approach validated with experimental characterization. The spray cooling system was modi ed to include thermal circuit paths that emerged during the testing of the prototypes and integrated in the current release of the software. The experimental characterization shows promising results, with peak output power at a base speed of 4,000 RPM exceeding 80 kW for the WFSM prototypes, and a continuous power output of 60 kW with the spray cooling system. The prototyped WFSMs achieve volumetric and speci c torque and power densities of 17.22 Nm/l, 4.69 Nm/kg, 7.19 kW/l, and 1.95 kW/kg. The experimental data collected for the HESM prototype shows a no-load rotor-side ux weakening capability that enables constant power speed ratio of 10:1 during operation and provides a exible platform for machine characterization and advanced control development for one monoaxial and one biaxial hybrid excitation synchronous machine con gurations. The design of the HESM prototype was obtained with an integration of analytical sizing equations for the initial exploration of the design space and FEA methods for detailed modeling of the nal prototype features.Ph.D. in Electrical Engineering, May 201