SUBJECT: Ph.D. Dissertation Defense
BY: Stephen Semidey
TIME: Monday, June 4, 2012, 12:00 p.m.
PLACE: MRDC Building, 4211
TITLE: Thermal Design and Optimization of High Torque Density Electric Machines
COMMITTEE: Dr. J. Rhett Mayor, Chair (ME)
Dr. Bert Bras (ME)
Dr. Ronald G. Harley (ECE)
Dr. Sheldon Jeter (ME)
Dr. Yogendra Joshi (ME)


This work addresses the design of next-generation, high torque density electrical machines through numerical optimization using an integrated thermal-electromagnetic design tool that accounts for advanced cooling technology. This was accomplished by first developing a parametric thermal model of electric machines. This model was implemented using a finite difference approach. The model was extended to include a novel advanced cooling technology termed the direct winding heat enhancer (DWHX). This technique involves placing a heat exchanger directly next to the windings in the stator, dramatically improving the thermal transport within the machine, thus increasing torque density. The DWHX requires high convection coefficient with low pressure drop. This tradeoff was addressed by developing an empirically based Nusselt number and friction factor correlation for micro-hydrofoil enhanced meso-channels. The parametric thermal model, advanced cooling technique, Nusselt number correlation, and friction factor correlation were combined with an electromagnetic model. The integrated thermal-electromagnetic model was then used in conjunction with particle swarm optimization to quickly determine optimal conceptual designs.