Low Resistance Heat Paths Application to Electric Machines Rotor Cooling

Thermal non-uniformities in electric machines manifested as local hotspots and high temperature gradients, pose significant risks to machine safety, leading to heightened thermal stresses and an increased likelihood of component failures. In this research, a newly developed 150 kW high-speed machine exhibited significant thermal imbalances, leading to hot spots near bearing seats. To mitigate these challenges, the paper proposes the use of integrated low-resistance heat paths in the steel rotor, replacing traditional void entities with lightweight, highly conductive materials such as aluminum or copper. Computational Fluid Dynamics (CFD) simulations demonstrate the effectiveness of an aluminum insert, resulting in a significant 47°C reduction in maximum shaft temperature and improved thermal uniformity. Structural analysis guides the optimization of fit parameters, defining a transition fit for maximum stress within yield strength. This comprehensive approach offers a strategic solution for enhancing rotor thermal management in high-speed electrical machines.