Novel Blade-Shaped Rotor Hub Design for Electric Machine Cooling

This paper proposes a novel blade-shaped rotor hub structure for the cooling of electric machines. As the rotor rotates, blades in the rotor hub function as a fan that draws air from the ambient environment into the machine. Radial inlets and outlets are designed in the machine housing to direct the airflow over the end windings, stator, and rotor surfaces in order to provide cooling by forced convection. An interior permanent magnet machine is designed using this proposed rotor hub structure. The stress on the rotor hub is simulated using SolidWorks. Finite element analysis is used to evaluate electromagnetic performances. The fan curve of the rotor hub, pressure drops in the front and rear housing, and surface heat transfer coefficients are obtained using computational fluid dynamics simulations. The calculated surface heat transfer coefficients are used in a thermal analysis of the machine, and results show that the proposed machine can be effectively cooled using only the airflow provided by the proposed rotor hub.