Electromagnetic - Thermal coupled optimization of high power traction drive induction machines

In the electrical machines, operated in railway traction drives, the growth of power density requires overproportional more heat to be discharged which leads to the need for more and more advanced cooling techniques. A novel optimization and evaluation approach for internal air cooled traction machines will be presented in this paper. It analyses and investigates the thermo-aeroand thermodynamic cooling performance combined with the electromagnetic performance. As a first step, analytical models are used to speed up calculation time for obtaining pressure drop, volume flow distribution and heat transfer as well as iron stack temperature. The results are validated using CFD (computational fluid dynamics simulations) of several iron stack cooling duct geometries. Finally, an approach is presented about on the optimization can be implemented, by coupling the analytic thermal model, CFD tool and electromagnetic losses obtained by finite element analysis. Keywords— analytical models, AC motor drives, design optimization, induction machines, thermal management of electronics, traction motors